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Zinzani, Michele. "Electric drives for ORTO - Orchard Rapid Transit Operation". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021.
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This thesis is focused on a novel agricultural technique for orchard cultivations that allows to perform automatic and fossil fuel free cultivation operations. More specifically, the aim of this thesis work is to study and implement the electric traction system and control the vehicle that performs the automatic operations.
Starting from the analysis of each single component of the traction system, the control of the mobile platform will be then performed.
After a first control of the mobile platform in no load conditions, the implementation of the dynamic model will be performed in the Simulink environment. Different simulations representing typical operational missions will be performed to have a real idea concerning the behaviour of the traction system and the energy consumption of this solution.
Finally, the obtained results will be analysed for the future implementation of the mobile platform on the field.
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Raju, Srinath. "Application of an automatic data acquisition system in mass transit". Thesis, Virginia Tech, 1987. http://hdl.handle.net/10919/44064.
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A robust algorithm has been developed to do data processing accurately, removing the need for a radio signal to be imbedded for locational accuracy. This, consequently eliminates the signposts installation and maintenance costs and worries. A sensitivity analysis of the algorithm using a real life data file revealed that the matching process change with changes in system parameters, adding credibility to the technique used for matching in the algorithm.
Next, several new programs have been added to bring together a software package yielding management reports and plots. These reports and plots are tremendous decision aiding tools and since the programs are interactive, the package is easy to use. A user's manual has also been developed.
Finally, an implementation of the Automated Data Acquisition System at TRT, Norfolk, is discussed. A systematic approach to the software development to meet the needs of the transit property has been conceptualized and specific software developed. A discussion of the details of this software development has been addressed, too.
In essence, Automatic Data Acquisition systems research at Virginia Tech has now evolved to such a stage that with a little "tuning" of hardware & the associated software, a very powerful and versatile automated data collection and management aiding tool will be available for economical widespread implementation.Master of Science
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Jain, Priyanka. "The effects of privatization, deregulation and decentralization on theefficient operation of urban mass transit railways". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2004. http://hub.hku.hk/bib/B3862865X.
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Jain, Priyanka. "The effects of privatization, deregulation and decentralization on the efficient operation of urban mass transit railways". Click to view the E-thesis via HKUTO, 2004. http://sunzi.lib.hku.hk/HKUTO/record/B3862865X.
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Yuce, Elif Can. "An Assessment Of The Planning And Operational Performance Of The Bus Rapid Transit In Istanbul". Master's thesis, METU, 2013. http://etd.lib.metu.edu.tr/upload/12615683/index.pdf.
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In Turkey, the only city that currently operates BRT is Istanbul. There are researches that focus on different BRT systems in the world, yet there has not been a comprehensive, systematic and comparative evaluation of the BRT experience in Istanbul. There seems to be an urgent need to study this BRT investment, with a particular focus on planning, operation and ridership characteristics with a comparative approach.
This thesis analyses the BRT corridor in Istanbul and answers the question whether Metrobüs in Istanbul is a success or not. In order to understand the criteria for defining success, planning, operation and ridership characteristics are identified based on the previous literature and particularly the analysis of three best practice cases that currently operate BRT
these are Curitiba, Bogota and Mexico City. The study sets the criteria in planning, operation and ridership of BRT systems drawn by previous studies and answers by people who were involved in these projects. It compares the best practice cases and the Istanbul Metrobü
s
focusing on planning and operation characteristics and using primary indicators of performance and ridership. The study reveals strength and weaknesses of the Istanbul Metrobü
s in comparison to best practice BRT cases in the world. The findings provide lessons both for the future extensions of the BRT in Istanbul and for other cities that may consider implementing this transit technology.
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Elmitiny, Noor. "SIMULATION AND CONTINUANCE OF OPERATION FOR THE USE OF TRANSIT (LYNX) TO BE USED IN EMERGENCY EVACUATION INCIDENTS". Master's thesis, University of Central Florida, 2006. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3475.
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The evacuation planning has become an important issue addressed by many research studies and publications aiming to improve the security of the daily life for our public inside the United States of America. The main objective of this research was to address the growing need for evacuation planning using traffic simulation. With increased interests and awareness in emergency evacuation and first responder access to emergencies in public locations (airports, transit stations, ports or stadiums), the traffic simulation can be helpful in orchestrating the traffic flow during emergencies. Related to this issue, Federal Transit Administration has issued a large number of publications and guidelines concerning emergency preparedness and incident management. These guidelines are used to develop a simulation-based activity to evaluate the current plan and alternative plans for the deployment of transit during an emergency situation. A major task for this project is to study the effect of evacuation on the surrounding traffic network and help the local transit company (LYNX) to evaluate their evacuation plan and consider different possibilities without the risk and cost of actual evacuation drills. A set of different scenarios and alternatives for each scenario were simulated and studied to reach the best possible evacuation strategy. The main findings were evacuation as pedestrians have less impact on traffic network and rerouting decreases the congestion resulting from the evacuation process.M.S.
Department of Civil and Environmental Engineering
Engineering and Computer Science
Civil Engineering
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Tsang, Kwan-ming. "Application of operation research techniques for forecasting transportation demand, planning train services and station facilities of the MTRC". Hong Kong : The University of Hong Kong, 1998. http://sunzi.lib.hku.hk/hkuto/record/B42574717.
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Duff-Riddell, W. R. (Wayne Russell). "A computerised decision support system for the implementation of strategic logistics management optimisation principles in the planning and operation of integrated urban public transport". Thesis, Stellenbosch : Stellenbosch University, 2001. http://hdl.handle.net/10019.1/52067.
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Thesis (PhD)--University of Stellenbosch, 2001.ENGLISH ABSTRACT: Public and private transport system planning and operation have tended to be fragmented functions. In particular, public transport is often planned and operated independently of the "private" transport system. South African government policy now requires that comprehensive, strategic transport plans be prepared by metropolitan transport authorities. These plans are expected to conform to national strategic objectives as well as including local current and longterm objectives. This planning is required in the environment of a multi-modal, multi-operator, public-private partnership scenario that is new for most of the role players. The lack of experience is accompanied by a lack of any existing model for dealing with this scenario. This dissertation describes such a model. The model is based on the principles of strategic logistics management commonly employed in commerce and industry, including service-oriented industries. The modelling process is thus based on achieving a combination of customer service and long-term objectives. The model comprises a number of separate components and steps: • A transport network model (Emme/2). ~ A multi-class, generalised-cost assignment of private and public transport demand onto a network, modified to be modeless to the public transport users, is performed. This assignment allows for the imposition of generalised-cost reflecting urban-planning objectives in addition to more conventional costs such as travel cost. In this assignment, the interaction of public and private transport is accounted for and results in an associated modal choice. ~ A series of single-class generalised-cost assignments is then used to "focus" public transport demand to create corridors of demand adequate to justify public transport routes. This process can be enhanced to develop a design promoting switching from private to public transport. It also allows for multi-period route design. ~ The results of this modelling process are output to a text file and then subject to the processes described below. The results of these processes are then input into the network model where a standard transit assignment is performed and used to modify the proposed lines and update the network design data with respect to boardings and alightings at nodes. This information is used to design fixed infrastructure. • A Microsoft Access database and route extraction program. );> The network model data is drawn into the database where it is subject to a route extraction program that converts the assignment results from the network model into a set of mode specific potential public transport route definitions. These route definitions are based on paths of maximum demand. The extraction process is controlled by parameters specified by the planner, such as minimum route lengths and the demand level for various categories of service. );> After route extraction, vehicle allocation, and transit assignment, the database provides details of the boardings and alightings and number and details of transit lines using each node and link in the network. This data is used to design fixed infrastructure. • A Microsoft Excel spreadsheet vehicle operating cost model. );> For each vehicle type, the operating cost given the anticipated vehicle mileage and operating speed is determined. This is used to guide the choice of vehicles for different routes. • A Lingo goal-programming model. );> The potential routes and the available or potential fleet are subjected to a goalprogramme in which the optimum choice of vehicle allocation is determined. The allocation parameters can be controlled by the planner. These parameters may include costs, energy, fuel consumption, and vehicle and route limitations amongst others. Multiperiod design is included in the modelling process so that the optimum design may be for the operating period, daily, or weekly cycle. The modelling process provides two main outputs: • A set of fully described and costed transit lines ill terms of both routing and vehicle allocation. These transit line definitions can be output to the level of driver instructions if necessary. • Details of the type and location of infrastructure to be provided on the network.
AFRIKAANSE OPSOMMING: Openbare en private vervoerstelsel-beplanning en -bedryf IS geneig om gefragmenteerde funksies te wees. Dit is veral waarneembaar in die openbare vervoerstelsels waarvan die beplanning en bedryf onafhanklik van die "private" vervoerstelsels plaasvind. Die beleid van die Suid-Afrikaanse regering vereis dat omvattende strategiese vervoerplanne deur die metropolitaanse vervoer owerhede voorberei word. Daar word van hierdie planne verwag om aan die nasionale strategiese doelwitte, asook die plaaslike bestaande en langtermyn doelwitte te voldoen. Hierdie beplanning word vereis deur 'n omgewing wat nuut is vir die meeste rolspelers en bestaan uit multi-modale, multi-operateur en openbare-private vennootskap scenario's. Die tekort aan ondervinding gaan gepaard met 'n tekort aan 'n bestaande model wat gebruik kan word om hierdie scenario's te hanteer. So 'n model word deur hierdie verhandeling beskryf. Die model is gebasseer op die beginsels van strategiese logistieke bestuur wat algemeen gebruik word in die handel en industrie, insluitende die diens-georïenteerde industrieë. Die modelleringsproses wil dus 'n kombinasie van diens aan kliënte en langtermyn doelwitte bereik. Die model bestaan uit onderskeie komponente en stappe: • 'n Vervoernetwerkmodel (Emmel2) }i;> 'n Multi-klas, veralgemeende-koste toedeling van private en openbare vervoeraanvraag op 'n netwerk, aangepas om modusloos te wees vir die openbare vervoergebruiker, word uitgevoer. Hierdie toedeling laat nie net die heffing van meer konvensionele kostes, soos reiskoste toe nie, maar ook veralgemeende kostes wat staatsbeplarmingsdoelwitte reflekteer. In hierdie opdrag word die interaksie van openbare- en private vervoer ondersoek waarvan die uiteinde 'n geassosieerde modale keuse is. }i;> 'n Reeks enkelklas veralgemeende koste toedelings word dan gebruik om op openbare vervoeraanvraag te fokus en daardeur korridors van aanvraag, wat gepas is om openbare vervoerroetes te regverdig, te skep. Hierdie proses kan verfyn word om 'n plan te ontwikkel wat die verskuiwing van private vervoer na openbare vervoer sal bevorder. Dit laat ook die ontwerp van multi-periode roetes toe. }i;> Die resultate van hierdie modelleringsproses word uitgevoer na 'n tekslêer en dan aan die prosesse, wat hier onder beskryf word, onderwerp. Die resultate van hierdie prosesse word dan ingevoer in die netwerkmodel waar 'n standaard publieke vervoertoedeling uitgevoer word. Dit word dan gebruik om die voorgestelde roetes te wysig en die netwerk data, met betrekking tot die aantal persone wat op en af klim by nodes, op te dateer. Hierdie inligting word gebruik vir die ontwerp van infrastrukture. • 'n Microsoft Access databasis en roete-ontrekkingsprogram );> Die netwerkmodel data word in die databasis ingetrek waar dit aan 'n roeteontrekkingsprogram onderwerp word. Hierdie program skakel die toedelingsresultate van die netwerkmodel om na 'n stel potensiële modus spesifieke openbare vervoerroete definisies. Hierdie roete definisies word gebasseer op paaie van maksimum aanvraag. Die ontrekkingsproses word deur parameters, soos minimum lengte van roetes en die vlak van aanvraag van verskeie kategorieë van diens, wat deur die beplanner gespesifiseer word, gekontroleer. );> Na die ontrekking van roetes, voertuigtoekenning en vervoertoedeling, voorsien die databasis besonderhede van die aantal persone wat op en af klim asook die aantal en details van vervoerroete wat elke node en skakel in die netwerk gebruik. Hierdie data word gebruik om infrastrukture te ontwerp. • 'n Microsoft Excel sigblad voertuig bedryfskoste model )i> Vir elke tipe voertuig word die bedryfskoste, volgens die verwagte afstand en spoed van die spesifieke voertuig, bepaal. Die resultate word gebruik om die keuse van voertuie vir verskillende roetes te bepaal. • 'n Lingo doelprogrameringsmodel );> Die potensiële roetes en die beskikbare of potensiële vloot word onderwerp aan 'n doelprogram waarin die optimum keuse van voertuigtoekenning bepaal word. Die toekenningsparameters kan deur die beplanner gekontroleer word. Die parameters kan onder andere kostes, energie, brandstofverbruik en voertuig- en roete beperkings, insluit. Multi-periode ontwerp is ingesluit in die modelleringsproses sodat die optimum ontwerp vir die bedryfsperiode, daaglikse of weeklikse siklusse, kan wees. Die modelleringsproses lewer twee hoofuitkomste: • 'n Stel volledig beskrywende en koste berekende vervoerroete wat, indien nodig, na die vlak van bestuurder instruksies, uitgevoer kan word. • Details van die tipe en plek van infrastruktuur wat benodig word deur die netwerk.
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Madson, Cass y Jared Mauldin. "A baseline analysis of in-transit shipping time into and through the Fifth Fleet area of operation with respect to the supply chain last nautical mile". Monterey, California. Naval Postgraduate School, 2011. http://hdl.handle.net/10945/10645.
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MBA Professional ReportIn FY 2010, the Defense (DoD) spent more than $210 Billion on supply chain management. However, the Government Accountability Office has identified DoD supply chain management as a high-risk area, specifically forecasting, asset visibility, and materiel distribution. Additionally, the DoD has not developed the means to measure the effectiveness of implemented actions or defined root causes as they pertain to the warfighter. The purpose of this study is to examine current supply chain practices and procedures within the the Navy (DoN). The goal is to provide a baseline for comparing the in-transit shipping times of three shipping priority categories to identify potential problem areas within the DoN logistics network, specifically within the Fifth Fleet area of operation (AOR). Identifying potential weaknesses within the supply chain provides suggestions for further study to best identify cost effective ways to improve material movement, processes, and to increase the readiness of the warfighter.
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Sun, Aichong. "AVL-BASED TRANSIT OPERATIONS CONTROL". Diss., Tucson, Arizona : University of Arizona, 2005. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu%5Fetd%5F1039%5F1%5Fm.pdf&type=application/pdf.
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Chaukar, Amar S. "Transit operations under emergency conditions". Birmingham, Ala. : University of Alabama at Birmingham, 2007. https://www.mhsl.uab.edu/dt/2007m/chaukar.pdf.
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Kirschbaum, Julie B. "Paying for transit operations : challenges and solutions for the Chicago Transit Authority". Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/17714.
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Thesis (M.C.P.)--Massachusetts Institute of Technology, Dept. of Urban Studies and Planning; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2004.Includes bibliographical references (p. 141-144).
This research identifies the challenges Chicagoland must confront to maintain a quality transit system. It analyzes the organizational and funding structure of the Regional Transportation Authority and its three service providers, including the Chicago Transit Authority. This investigation revealed that the greatest regional challenges are declining ridership (especially on bus) and increasing congestion from limited subsidies and a cost recovery statute. To address these challenges a series of alternatives were evaluated using a framework that considers revenue potential, incidence, side effects, and political feasibility. Based on this analysis, a four part strategy is recommended: 1. Change the current distribution formula. Unless a new allocation formula is established, CTA may not benefit from increased resources. The new formula should reduce reliance on discretionary funds by stabilizing current funding levels to the three service providers. 2. Increase RTA revenues. Currently the two wealthiest counties in the region (DuPage and Lake) pay significantly less than Cook County while enjoying comparable service. The RTA should increase their sales tax contributions to improve regional equity and increase resources. These resources should be used to address growing paratransit needs.
(cont.) 3. Develop a set of performance measures that respond to distinct transit markets. Rather than focusing exclusively on the cost recovery ratio, which risks the long-term vitality of the system, the RTA should develop a set of performance measures that maximize efficiencies within markets. This will allow the region to control costs, while still protecting weaker markets like bus and paratransit. 4. Include a transit pass as part of the personal vehicle registration tax. Having people prepay for transit services will provide an incentive for replacing some automobile trips, while generating regional subsidies. In the short run, this funding mechanism will serve as an incentive for RTA to promote fare integration. If expanded over time, it offers RTA the opportunity to increase transit service. The above recommendations will help reverse the current negative trends and stabilize ridership; however to increase ridership and mode share, more subsidy will be needed. Other promising revenue generators should be considered in the future to meet these goals.
by Julie B. Kirschbaum.
S.M.
M.C.P.
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Cruz-Mejia, Oliverio. "Merge-in-transit supply chains : operations analysis". Thesis, Lancaster University, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.543964.
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Rahbee, Adam B. "Rail transit operations analysis : framework and applications". Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/84305.
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Chung, Chor-mei. "The feasibility of enhancing transport coordination between railway and bus operations in Tsim Sha Tsui". Hong Kong : University of Hong Kong, 2000. http://sunzi.lib.hku.hk/hkuto/record.jsp?B22199251.
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Cats, Oded. "Dynamic Modelling of Transit Operations and Passenger Decisions". Doctoral thesis, KTH, Trafik och logistik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-49962.
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Efficient and reliable public transport systems are fundamental in promoting green growth developments in metropolitan areas. A large range of Advanced Public Transport Systems (APTS) facilitates the design of real-time operations and demand management. The analysis of transit performance requires a dynamic tool that will enable to emulate the dynamic loading of travelers and their interaction with the transit system. BusMezzo, a dynamic transit operations and assignment model was developed to enable the analysis and evaluation of transit performance and level of service under various system conditions and APTS. The model represents the interactions between traffic dynamics, transit operations and traveler decisions. The model was implemented within a mesoscopic traffic simulation model. The different sources of transit operations uncertainty including traffic conditions, vehicle capacities, dwell times, vehicle schedules and service disruptions are modeled explicitly. The dynamic path choice model in BusMezzo considers each traveler as an adaptive decision maker. Travelers’ progress in the transit system consists of successive decisions that are defined by the need to choose the next path element. The evaluations are based on the respective path alternatives and their anticipated downstream attributes. Travel decisions are modeled within the framework of discrete random utility models. A non-compensatory choice-set generation model and the path utility function were estimated based on a web-based survey. BusMezzo enables the analysis and evaluation of proactive control strategies and the impacts of real-time information provision. Several experiments were conducted to analyze transit performance from travelers, operator and drivers perspectives under various holding strategies. This analysis has facilitated the design of a field trial of the most promising strategy. Furthermore, a case study on real-time traveler information systems regarding the next vehicle arrival time investigated the impacts of various levels of coverage and comprehensiveness. As passengers are more informed, passenger loads are subject to more fluctuation due to the traveler adaptations.QC 20111201
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Srinivasan, Aravind. "SCHEDULING AND ROUTING FOR DEMAND RESPONSIVE TRANSIT OPERATIONS". NCSU, 2001. http://www.lib.ncsu.edu/theses/available/etd-20010726-020504.
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Aravind Srinivasan. Scheduling and Routing for Demand Responsive Transit Operations. (Under the direction of Dr. John W. Baugh and Dr. John R. Stone.)The multi-vehicle dial-a-ride problem has been proven to be intractable and NP-hard. Researchers have proposed numerous techniques for furnishing approximate solutions, but most ofthese aim at conquering a single objective, such as minimization of eet size. The chosen technique must handle multiple (different or competing) objectives that characterize the problem, so that it may lend itself as a tool in transit research. This thesis explores a new technique based on the cluster-first, route-second strategy, where the multiple competing objectives of the dial-a-ride problem are successfully addressed. The key highlights in this technique are the development of different routers for different stages of the optimization, and organism filters to guide the population of prospective solutions in the clustering phase of the optimization. Application and comparison to case study data indicate that the techniques developed outperform a commercial scheduling package in generating optimal schedules, and lend themselves to configuration and customization in order tosimulate different scenarios, which help in selecting demand-responsive transit policies.
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Croxton, Keely L., Bernard Gendon y Thomas L. Magnanti. "Models and Methods for Merge-In-Transit Operations". Massachusetts Institute of Technology, Operations Research Center, 2001. http://hdl.handle.net/1721.1/5135.
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We develop integer programming formulations and solution methods for addressing operational issues in merge-in-transit distribution systems. The models account for various complex problem features including the integration of inventory and transportation decisions, the dynamic and multimodal components of the application, and the non-convex piecewise linear structure of the cost functions. To accurately model the cost functions, we introduce disaggregation techniques that allow us to derive a hierarchy of linear programming relaxations. To solve these relaxations, we propose a cutting-plane procedure that combines constraint and variable generation with rounding and branch-and-bound heuristics. We demonstrate the effectiveness of this approach on a large set of test problems with instances with up to almost 500,000 integer variables derived from actual data from the computer industry. Key words : Merge-in-transit distribution systems, logistics, transportation, integer programming, disaggregation, cutting-plane method.
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Younan, Bassel J. 1979. "Improving transit service connectivity : the application of operations planning and operations control strategies". Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/28632.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2004.Includes bibliographical references (p. 131-133).
(cont.) showed that the benefits accrued from coordinating schedules on Route 53 were not significant mainly due to the headway compatibility requirement which reduces the number of transfers amenable for improvement. Greater benefits were encountered when the schedules on the connecting routes were allowed to change as well. For Route 63, schedule coordination is not worth attempting due to the combination of the short six-minute headway on that route and the high variability in vehicle arrival times. On the control side, the practice currently adopted at CTA is to hold a "ready" vehicle at a transfer stop if the connecting vehicle has already arrived and this is likely to be an effective as well as easy-to-implement control policy.
Providing direct public transportation service for every origin-destination pair is very expensive if not infeasible for a transit agency, so it relies on the willingness of passengers to transfer. However, transfers usually reduce the attractiveness of transit because they add uncertainty, discomfort, waiting time and cost to most trips. This research focuses on examining different transfer coordination strategies that can reduce the disutility of transfers by minimizing the expected waiting times of transferring passengers. Two models are developed to assess scheduling and real-time holding decision rules for vehicles on a transit corridor. The operations planning model involves the simultaneous application of two planning strategies: changing the terminal departure time and inserting slack time. The operations control model has the capability to utilize any available current network information and to determine optimal dispatch times for vehicles at transfer stops. The two models were tested on a hypothetical corridor to illustrate their applicability in coordinating transfers. On the planning side, results showed that there is a high threshold for introducing slack time to the schedule and that the greatest benefits from schedule coordination are attained when the variance of vehicle arrival times is small and the headway on the analysis corridor is long. On the control side, it was shown that transfer demand is a major driving factor behind any holding recommendation. Moreover, the greatest benefits from real-time coordination occur when the required holding time and the preceding headway of the vehicle on the destination line are short and its following headway is long. The application of the models to two CTA bus routes: 53 and 63,
by Bassel J. Younan.
S.M.
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Yan, Julia(Julia Y. ). "From data to decisions in urban transit and logistics". Thesis, Massachusetts Institute of Technology, 2020. https://hdl.handle.net/1721.1/127296.
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Thesis: Ph. D., Massachusetts Institute of Technology, Sloan School of Management, Operations Research Center, May, 2020Cataloged from the official PDF of thesis.
Includes bibliographical references (pages 145-155).
Urban transit and city logistics have undergone major changes in recent years, including increased peak congestion, shrinking mass transit ridership, and the introduction of ride-sharing and micro-mobility platforms. At the same time, widespread data collection offers transit agencies insight into their riders in unprecedented detail. In this setting, data has the potential to inform decision-making and make meaningful impact on problems of great public interest. This thesis concerns data-driven decision-making for public transit systems, and spans topics from demand estimation to the design and operation of fixed-route systems and paratransit. The first chapter is concerned with origin-destination demand estimation for public transit. Our aim is to estimate demand using aggregated station entrance and exit counts, which can be modeled as the problem of recovering a matrix from its row and column sums.
We recover the demand by assuming that it follows intuitive physical properties such as smoothness and symmetry, and we contrast this approach both analytically and empirically with the maximum entropy method on real-world data. The next two chapters then use this demand data to inform strategic transit planning problems such as network design, frequency-setting, and pricing. These problems are challenging alone and made even more difficult by the complexity of commuter behavior. Our models address operator decision-making in the face of commuter preferences, and our approaches are based on column generation and first-order methods in order to model complex dynamics while scaling to realistic city settings. Finally, we explore tactical decision-making for paratransit. Paratransit is a government-mandated service that provides shared transportation for those who cannot use fixed routes due to disability.
Although paratransit is an essential safety net, it is also expensive and requires large government subsidies. These financial difficulties motivate us to develop large-scale optimization algorithms for vehicle routing in paratransit. We provide an optimization-based heuristic approach to servicing paratransit requests subject to labor constraints; this approach shows strong performance while also being tractable for several thousand daily requests..
by Julia Yan.
Ph. D.
Ph.D. Massachusetts Institute of Technology, Sloan School of Management, Operations Research Center
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Karim, Md Ahsanul. "Transit operations, city transportation plans and overall transportation network safety". Thesis, University of British Columbia, 2011. http://hdl.handle.net/2429/33739.
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Modern transportation planning considers issues such as road congestion, pollution and mobility proactively. However, road safety is usually evaluated in a reactive manner only after the implementation of transportation plans, and when safety problems arise. Although this reactive road safety approach has been very effective, it is associated with significant costs on communities. Therefore, several researchers advocate a more proactive approach to road safety analysis. Several studies developed macro-level Collision Prediction Models (CPMs) that could assess the road safety in a proactive manner, and provide a safety planning decision support tool to community planners and engineers. However, these models have limitations as they do not target the safety evaluation of different goals of a typical city transportation plan. Therefore, the motivation for this research arises from the necessity of developing tools that could predict the safety effect of a typical city transportation plan such as changes in the transportation and transit network configurations, and ultimately could evaluate the safety estimates among alternatives of different transportation plans and policies.
The main goal of this thesis is to develop a set of macro-level collision prediction models to investigate the relationships between various transportation and sociodemographic characteristics, and the overall roadway safety. The developed models consider the Poisson variations and the heterogeneity (extra-variation) on the occurrence of collisions and the spatial effects on the distribution of collisions caused by the similarity in environment and geography of the neighbouring sites. It has been shown that the goodness of fit improved with the incorporation of spatial effect.
In this study, a set of zonal-level transit reliant and application-based collision prediction models were developed. Data from Metro Vancouver, British Columbia were used to develop models using a generalized linear modelling approach with a negative binomial error structure. Different transit-related variables were found to be statistically significant, namely bus stop density, percentage of transit-km traveled with regard to total vehicle-km traveled, percentage of commuters walking, percentage of commuters biking, and percentage of commuters using transit. The CPMs related total, severe, and property damage only collisions to the implemental aspects related to the goals of long-term transportation plans.
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Eberlein, Xu Jun. "Real-time control stategies in transit operations : models and analysis". Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/11387.
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Sánchez-Martínez, Gabriel Eduardo. "Real-time operations planning and control of high-frequency transit". Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/99550.
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Thesis: Ph. D. in Transportation, Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2015.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 135-140).
High-frequency transit systems are essential for the socioeconomic and environmental well-being of large and dense cities. The planning and control of their operations are important determinants of service quality. Transit operators are increasingly adopting data collection devices that enable real-time monitoring of vehicle locations and demand, but existing models and current practice limit the utility of this information. This research develops new concepts, frameworks, and models for real-time optimization of operations, utilizing both historical and real-time information originating from connected data collection devices, including automated vehicle location, automated fare collection, and automatic passenger counting systems. Previous control strategies either do not forecast system states or rely on forecasts based on running times and demand assumed to be static. This research develops an optimization model for holding-based control that incorporates dynamics, producing a holding policy that accounts not only for the current state of the system, but also for expected changes in running times and demand, due to both exogenous and endogenous dynamics. This information advantage can lead to improved performance when a transit service faces typical changes in running times and demand over time, as well as potentially disruptive events such as signal failures, disabled rolling stock, and demand surges. Anticipatory control policies allow the transit service to react before disruptions develop. It is shown that information about dynamics is particularly valuable when it leads to better predictions of capacity being reached. Although headway and optimization-based control strategies generally outperform schedule-adherence strategies, high-frequency operations are mostly planned with schedules, in part because operators must observe resource constraints (neglected by most control strategies) while planning and delivering service. This research develops a schedule-free paradigm for high-frequency transit operations, in which trip sequences and departure times are optimized in real-time, employing stop-skipping strategies and utilizing real-time information to maximize service quality while satisfying operator resource constraints. Following a discussion of possible methodological approaches, a simple methodology is applied to operate a simulated transit service without schedules. Results demonstrate the feasibility of the new paradigm and suggest possible methodology improvements.
by Gabriel Eduardo Sánchez-Martínez.
Ph. D. in Transportation
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Deckoff, Anthony Adlai. "The short-turn as a real time transit operating strategy". Thesis, Massachusetts Institute of Technology, 1990. http://hdl.handle.net/1721.1/41774.
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Chung, Chor-mei y 鍾楚媚. "The feasibility of enhancing transport coordination between railway and bus operations in Tsim Sha Tsui". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2000. http://hub.hku.hk/bib/B31952574.
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Allan, Mitchell J. "Are Nudges for Alternative Transit Persistent?" Scholarship @ Claremont, 2019. https://scholarship.claremont.edu/cmc_theses/2246.
Texto completoResumen
The benefits of converting single-person drivers to alternative transit options are well-established. One option to accomplish this is for employers to provide alternative commute incentive programs. However, the research on the implementation of such programs is lacking. To provide a test, this research analyzes data obtained from a field experiment on daily alternative transit commute choices for a seven-month period. Participants are divided into four treatment groups in a two-by-two design for the first three-month period: incentives with either loss or gain framing, and messaging nudges with either the private or public benefits of alternative transit commute choices. The participants then continue in the field experiment for the remaining four-month period with all groups receiving only gain framing incentives and messaging nudges are discontinued. The results from the two time periods are compared. Loss framing and private messaging have the most significant effect on participants’ decisions to revert back to single-person driving when nudges are discontinued, and thus nudges are not persistent. The incentive program did not provide enduring conversion to alternative transit options, but the results suggest employers who want to optimize their alternative transit incentive programs should utilize loss framing incentives and combine both private and public messaging into continuous nudges.
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Hickey, April M. "Utilizing ATCS Data to Inform a Dynamic Reassignment System for Muni Metro Light Rail Vehicles Departing Embarcadero Station". DigitalCommons@CalPoly, 2013. https://digitalcommons.calpoly.edu/theses/1081.
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This is a report of a professional project intended to act as an informational tool for the evaluation of a dynamic dispatch system at Embarcadero Station for the San Francisco Municipal Transportation Agency (SFMTA). Systems that operate dispatch algorithms do so in response to on-time performance and reliability. The optimization problem is documented in many transportation contexts including airline networks, bus dispatch, and freight routing. According to the research, optimizing available options and re-routing based on available options can create a more efficient system that would minimize operating costs and improving service reliability for customers.
The methodology presented here uses current headway information to dynamically change dispatch assignment between J, L, and M lines. The reassignment program was applied to randomly selected weekdays in March of 2012. After analysis it was determined that the application has the potential to decrease mean operating headways by up to 3% (or approximately 15 seconds).
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Chiraphadhanakul, Virot. "Large-scale analytics and optimization in urban transportation : improving public transit and its integration with vehicle-sharing services". Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/82190.
Texto completoResumen
Thesis (Ph. D.)--Massachusetts Institute of Technology, Sloan School of Management, Operations Research Center, 2013.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 143-154).
Public transportation is undeniably an effective way to move a large number of people in a city. Its ineffectiveness, such as long travel times, poor coverage, and lack of direct services, however, makes it unappealing to many commuters. In this thesis, we address some of the shortcomings and propose solutions for making public transportation more preferable. The first part of this thesis is focused on improving existing bus services to provide higher levels of service. We propose an optimization model to determine limited-stop service to be operated in parallel with local service to maximize total user welfare. Theoretical properties of the model are established and used to develop an efficient solution approach. We present numerical results obtained using real-world data and demonstrate the benefits of limited-stop services. The second part of this thesis concerns the design of integrated vehicle-sharing and public transportation services. One-way vehicle-sharing services can provide better access to existing public transportation and additional options for trips beyond those provided by public transit. The contributions of this part are twofold. First, we present a framework for evaluating the impacts of integrating one-way vehicles haring service with existing public transportation. Using publicly available data, we construct a graph representing a multi-modal transportation service. Various evaluation metrics based on centrality indices are proposed. Additionally, we introduce the notion of a transfer tree and develop a visualization tool that enables us to easily compare commuting patterns from different origins. The framework is applied to assess the impact of Hubway (a bike-sharing service) on public transportation service in the Boston metropolitan area. Second, we present an optimization model to select a subset of locations at which installing vehicle-sharing stations minimizes overall travel time over the integrated network. Benders decomposition is used to tackle large instances. While a tight formulation generally generates stronger Benders cuts, it requires a large number of variables and constraints, and hence, more computational effort. We propose new algorithms that produce strong Benders cuts quickly by aggregating various variables and constraints. Using data from the Boston metropolitan area, we present computational experiments that confirm the effectiveness of our solution approach.
by Virot Chiraphadhanakul.
Ph.D.
29
Maddox, Brian C. "Emerging role of activity center transportation organizations in traffic operations services". Thesis, Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/49038.
Texto completoResumen
The TMA Traffic Operations Survey was developed, which focused on traffic operations services and transportation system management practices of TMOs. The survey had the following structure: background, membership, services, and follow-up. The survey was emailed to 157 TMOs around the nation and 35 responses were received, a 22.2% response rate. Of the participating organizations only five (17%) organizations provided traffic services including traffic control improvements, signal timing, and collection of traffic data.
These findings determined that a minority of organizations are involved in traffic operations. The multiple organizations that are involved in traffic operations provided data on their websites including incident alerts, live traffic views, and real-time traffic or shuttle information. Very few of the organizations that used data to provide traffic operations services generated the data themselves. The research results determined that few organizations are actively attempting to assume a role in traffic operations.
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Albrecht, Thomas. "Ein Beitrag zur Nutzbarmachung Genetischer Algorithmen für die optimale Steuerung und Planung eines flexiblen Stadtschnellbahnbetriebes". Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2005. http://nbn-resolving.de/urn:nbn:de:swb:14-1121927087918-09162.
Texto completoResumen
The work deals with two problems of mass rapid transit system operation: The development of flexible timetables and the realisation of flexible timetables. In both cases, genetic algorithms are used. In the process of (flexible) timetabling in suburban railways, a transport offer perfectly adapted to demand is searched for (temporal and spatial adaptation of demand as well as adaptation of capacity of the trains). After determination of the number of train runs per line and hour and their capacity, optimal departure times have to be found (with a precision of a minute down to 10 s), which fulfil criterias of the passengers (short waiting times) as well as of the operator (small number of vehicles needed). Two different codings for use with genetic algorithms have therefore been developed. They are tested on several case studies of the Dresden suburban railway network, assuming different degrees of flexibilisation. In the process of realising a flexible timetable, transitions between train headways as well as running time and dwell time reserves (margins in the order of a few seconds) are slightly modified in order to coordinate braking and accelerating trains and thereby reduce energy costs of a system of trains. Genetic algorithms can be applied for this problem as well, the proposed methods are tested on several case studies (S-Bahn Berlin, Metro Lille)Die Arbeit behandelt zwei Probleme der Betriebsplanung von Stadtschnellbahnen: Die Erstellung flexibler Fahrpläne und die Umsetzung flexibler Fahrpläne. In beiden Fällen werden zur Lösung Genetische Algorithmen verwendet. Bei der Ermittlung flexibler Fahrpläne von S-Bahnen wird ein bestmöglich an die Verkehrsnachfrage angepasstes Verkehrsangebot gesucht (zeitlich, räumlich und bezüglich der Kapazität der einzelnen Züge angepasst). Nach stundenfeiner Festlegung der Fahrtenhäufigkeiten und Kapazitäten der einzelnen, sich überlagernden Linien werden deren Abfahrtszeiten gesucht (mit einer Genauigkeit von Minuten bis etwa 10 s), so dass sowohl die Wünsche der Fahrgäste nach gleichmäßigen Zugfolgezeiten als auch Betreiberwünsche (geringe Fahrzeuganzahl) erfüllt werden. Hierzu werden zwei verschiedene Kodierungen für die Verwendung mit Genetischen Algorithmen vorgestellt und das geschaffene Verfahren an verschiedenen Flexibilisierungsszenarien für die S-Bahn Dresden erprobt. Bei der Umsetzung flexibler Fahrpläne, die sich im Bereich weniger Sekunden abspielt, werden Übergänge zwischen Zugfolgezeiten, Fahr- und Haltezeitreserven geringfügig modifiziert, so dass durch bestmögliche Koordination von Anfahr- und Bremsvorgängen eines Systems von Zügen die Energiekosten minimal werden. Methodisch werden wiederum Genetische Algorithmen verwendet, die Erprobung des Verfahrens erfolgt anhand von Linien der S-Bahn Berlin und der Metro in Lille
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Truong, Gold. "Forecasting linehaul transit times & on time delivery probability using quantile regression forests". Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/90751.
Texto completoResumen
Thesis: M.B.A., Massachusetts Institute of Technology, Sloan School of Management, 2014. In conjunction with the Leaders for Global Operations Program at MIT.Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2014. In conjunction with the Leaders for Global Operations Program at MIT.
Cataloged from PDF version of thesis.
Includes bibliographical references (page 85).
with delays on the road and variabilities introduced by the major participants in the process, ie: distribution centers, drivers, etc. These sources of variability also make it difficult to measure the impact changes in transit time have on on-time performance. This paper focuses on trying to identify indicators of variability and incorporates them into quantile regression forest, a black box forecasting model, that will provide estimated scheduled transit times for a given probability of on-time arrival at the destination. With the use of Amazon's Q1 & Q2 2013 linehaul data, an analysis on performance trends based on length of haul were categorized to develop an understanding linehauls in North America. The outbound transportation team at Amazon faces the complex trade off between providing a sufficient amount of scheduled transit time to ensure ontime delivery to destination and the utilization rate of a truck. The ability to quantify how changes in scheduled transit time impact the performance of a particular linehaul allows transportation managers to assess this trade off. The paper explores a machine learning regression technique called quantile regression forests. The model was developed in R using the quantregforest package. It incorporates numerous factors about linehaul including: origin, destination, historical reporting on sources of late to arrivals, time to depart from origin and time of departure. The strengths of this black box model are in its ability to handle a large amount of data and continuously update its predicting structure to provide more accurate recommendations. Quantile regression forests also enable the user to specify the ontime performance percentage, p, that he/she wants the model to predict based on historical data. The final model at p = 95% provided a weight mean absolute percent error of 4.57% and a root mean square error of 2.22%. A four-week pilot was conducted to validate these predictions and the results are discussed.
by Gold Truong.
M.B.A.
S.M.
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Weigel, Brent Anthony. "Development of a calculator for estimation and management of GHG emissions from public transit agency operations". Thesis, Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/34840.
Texto completoResumen
As managers of extensive vehicle fleets and transportation infrastructures, public transit agencies present unique opportunities for reducing greenhouse gas (GHG) emissions from the transportation sector. To achieve substantial and cost-effective GHG emissions reductions from their activities, public transit agencies need tools and resources that enable effective GHG emissions management. This research thesis presents the background, methodology, and results of the author's development of a public transit agency-level life cycle GHG emissions calculator.
The development of the calculator involved a series of research efforts aimed at identifying and addressing the needs of transit agency GHG emissions management: a review of background information on climate change and public transit's role in mitigating climate change; a review of existing GHG emissions calculators for public transit agencies, a review of the methodologies for life cycle GHG emissions analysis; integration and adaption of existing calculation resources; development of calculator spreadsheets for estimating relevant lifecycle GHG emissions and quantifying GHG emission reduction cost-effectiveness; application of the developed calculator to a carbon footprint analysis for a typical mid-size to large-size transit agency; and application of the developed calculator to the evaluation of the cost-effectiveness of various potential strategies for reducing transit agency GHG emissions.
The developed calculator provides an integrative resource for quantifying GHG emissions and costs of public transit agency activities, including GHG emission reduction strategies. Further research is needed to calibrate the estimation of upstream life cycle GHG emissions, particularly for vehicle manufacture and maintenance.
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Himadri, Pandey. "Fabrication, Characterization and Simulation of Graphene Field Effect Transistors operating at Microwave Frequencies". Thesis, KTH, Skolan för informations- och kommunikationsteknik (ICT), 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-129401.
Texto completoResumen
With the end of Si based Metal Oxide Semiconductor Field Effect Transistor scaling paradigm approaching fast as predicted by the Moore’s Law, and the technological advancements as well as human needs in many ways pushing for faster devices, graphene has emerged as a powerful alternative solution. This is so because of its very special properties like high charge carrier mobility, highly linear dispersion relation, high current carrying capacity and so on. However, since we have a finite resistance at Dirac point, the on/off ratio in graphene devices is sufficiently low, making graphene devices not so suitable for logical applications. At the same time, the 1/f noise, which is understood till now to originate from surface disorders like those observed in a two-dimensional electron gas system like graphene and is a major unwanted outcome in mesoscopic regime devices, reduces very much at high frequencies, making these devices good candidates for high frequency analogue applications. Motivated by these observations, this work explores fabrication and characterization of graphene field effect transistors operating at microwave frequencies, and compares a double gated device performance to a mono-gated device having the same geometry, dielectric layer thickness and gate length. A simple electrostatic finite element simulation model has also been developed to support our experimental observations by fitting simulated gate coupling capacitance values to the measured data. The model helps us in understanding the level of interface trap charge densities introduced into the device channel during fabrication, and the effect of quantum capacitance on device performance, and is in line with the experimental observations. Our results show that a double gated graphene FET has superior performance compared to a mono-gated FET.
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Hoang, Hung. "Safety Implications of Transit Operator Schedule Policies". UNF Digital Commons, 2016. http://digitalcommons.unf.edu/etd/628.
Texto completoResumen
In the bus transit community, driving long hours or spending extra hours at work are very common. This is true in the State of Florida, where bus transit is a very popular mode of public transportation. Although the correlation between a bus driver’s schedule and a crash event appears intuitive, further study regarding the effects of operator driving schedules on accident rates is needed to evaluate safety measures. The focus of this research is on the examination of bus driver schedules, and the effects of scheduling on accident rates in Florida. Data were collected at five bus transit agencies including Jacksonville Transportation Authority (JTA), Central Florida Regional Transportation Authority (LYNX), Hillsborough Area Regional Transit Authority (HART), Miami-Dade Transit (MDT) and StarMetro in Tallahassee. Data collected included bus operator work schedules, accident data, and a voluntary questionnaire survey. The results indicate that the number of working hours significantly affect driving quality and increase the likelihood of driver involvement in a bus crash. Based upon 410 surveys obtained from operators, over 21% of drivers were concerned about the effects of split-time on fatigue. In addition to split-time considerations, the study revealed that nearly 15% of operators who completed the survey had a secondary driving job. The review of operator schedules also indicated that drivers involved in preventable accidents spent longer hours at work than on actual driving duty, primarily due to extended split-time. Consequently, drivers who had more than two hours of break had a higher probability of being involved in a preventable collision compared to drivers with less than two hours of split-time.
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Bromfield, Stephanie Antoinette. "Operational and safety effects of signage and lighting configurations for public transit buses in Florida". [Tampa, Fla.] : University of South Florida, 2007. http://purl.fcla.edu/usf/dc/et/SFE0002062.
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Albrecht, Thomas. "Ein Beitrag zur Nutzbarmachung Genetischer Algorithmen für die optimale Steuerung und Planung eines flexiblen Stadtschnellbahnbetriebes". Doctoral thesis, Technische Universität Dresden, 2004. https://tud.qucosa.de/id/qucosa%3A24536.
Texto completoResumen
The work deals with two problems of mass rapid transit system operation: The development of flexible timetables and the realisation of flexible timetables. In both cases, genetic algorithms are used. In the process of (flexible) timetabling in suburban railways, a transport offer perfectly adapted to demand is searched for (temporal and spatial adaptation of demand as well as adaptation of capacity of the trains). After determination of the number of train runs per line and hour and their capacity, optimal departure times have to be found (with a precision of a minute down to 10 s), which fulfil criterias of the passengers (short waiting times) as well as of the operator (small number of vehicles needed). Two different codings for use with genetic algorithms have therefore been developed. They are tested on several case studies of the Dresden suburban railway network, assuming different degrees of flexibilisation. In the process of realising a flexible timetable, transitions between train headways as well as running time and dwell time reserves (margins in the order of a few seconds) are slightly modified in order to coordinate braking and accelerating trains and thereby reduce energy costs of a system of trains. Genetic algorithms can be applied for this problem as well, the proposed methods are tested on several case studies (S-Bahn Berlin, Metro Lille).Die Arbeit behandelt zwei Probleme der Betriebsplanung von Stadtschnellbahnen: Die Erstellung flexibler Fahrpläne und die Umsetzung flexibler Fahrpläne. In beiden Fällen werden zur Lösung Genetische Algorithmen verwendet. Bei der Ermittlung flexibler Fahrpläne von S-Bahnen wird ein bestmöglich an die Verkehrsnachfrage angepasstes Verkehrsangebot gesucht (zeitlich, räumlich und bezüglich der Kapazität der einzelnen Züge angepasst). Nach stundenfeiner Festlegung der Fahrtenhäufigkeiten und Kapazitäten der einzelnen, sich überlagernden Linien werden deren Abfahrtszeiten gesucht (mit einer Genauigkeit von Minuten bis etwa 10 s), so dass sowohl die Wünsche der Fahrgäste nach gleichmäßigen Zugfolgezeiten als auch Betreiberwünsche (geringe Fahrzeuganzahl) erfüllt werden. Hierzu werden zwei verschiedene Kodierungen für die Verwendung mit Genetischen Algorithmen vorgestellt und das geschaffene Verfahren an verschiedenen Flexibilisierungsszenarien für die S-Bahn Dresden erprobt. Bei der Umsetzung flexibler Fahrpläne, die sich im Bereich weniger Sekunden abspielt, werden Übergänge zwischen Zugfolgezeiten, Fahr- und Haltezeitreserven geringfügig modifiziert, so dass durch bestmögliche Koordination von Anfahr- und Bremsvorgängen eines Systems von Zügen die Energiekosten minimal werden. Methodisch werden wiederum Genetische Algorithmen verwendet, die Erprobung des Verfahrens erfolgt anhand von Linien der S-Bahn Berlin und der Metro in Lille.
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Zheng, Wei. "Control strategies enabling seamless switching to islanded operation". Thesis, University of Manchester, 2018. https://www.research.manchester.ac.uk/portal/en/theses/control-strategies-enabling-seamless-switching-to-islanded-operation(bbd0b08b-0a72-4c45-99de-c3b98f908058).html.
Texto completoResumen
Significant penetration of distributed generation (DG) and the increasing automation level available for distribution networks have opened an option of splitting a network into subsystems and operating each as an "autonomous island". This is particularly important when a major contingency occurs. However, there are issues and challenges that must be addressed before islanded operation becomes viable, among which, ensuring seamless switching of a distribution subsystem from grid-connected to islanded mode is critically important. Unless the subsystem is a predesigned microgrid, it is highly possible that the subsystem load demand will exceed the generation capacity of island DGs. Therefore, an appropriate load shedding scheme must be implemented to ensure the islanded subsystem is power balanced. In this thesis, a switching control strategy is designed to deliver seamless islanding switching. This strategy comprises a multiple-DG coordination method and a single-step load shedding scheme. Mathematical studies and time-domain simulations that investigate the transients observed during the islanding switching process are both conducted, and together, they are used to address the transient stability issues of an islanded subsystem. This thesis focuses on a distribution subsystem consisting of a mix of synchronous and inverter-based DGs and a combination of static and dynamic loads. DG modelling and control is first introduced, and based on that, various types of method to achieve multiple-DG coordination, including an innovative multiple-master strategy, are investigated. The widely accepted master-slave strategy is used to coordinate DGs when the subsystem is islanded. The strategy demands a single dispatchable and controllable DG, such as a synchronous generator, to be the master, whilst requires the others, such as intermittent renewable-based DGs, to be the slaves. Dynamic load modelling is another critical part of this thesis. The transient stability of dynamic loads after major disturbances is investigated and then used to design the stability-oriented load shedding priority. The single-step load shedding scheme calculates the load shedding amount based on the power flow at the point of common coupling (PCC) and the spinning reserve available in the island. This scheme is activated by the tripping event of the PCC circuit breaker between the grid and the island, and then priorities the load to be shed according to the priority predetermined from the stability perspective. Mathematical analysis is first conducted on a simple subsystem to investigate the impact of DG settings on the islanding transients. A full-scale subsystem is also simulated in PSCAD/EMTDC and used to verify the effectiveness of the switching control strategy. In time-domain simulations, the subsystem is islanded following either a routine switching event or a permanent grid fault. Various factors that may affect the transient performance are analysed, such as the severity of the fault, the DG penetration level, the fault clearance time and the switching control delay. This thesis concludes that based on the proposed switching control strategy, the concept of seamless switching from grid-connected to islanded operation is technically viable.
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Nicholas, Joshua Stephen. "Examination of Taxi Travel Patterns in Arlington County". Thesis, Virginia Tech, 2012. http://hdl.handle.net/10919/32606.
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This research focuses on utilizing the typically overlooked taxi manifest data to analyze taxi operations with respect to transit, and also presents alternative uses for the data in transportation planning. Taxi travel characteristics are explored for Arlington, Virginia, a county containing both urban and suburban qualities. Previous research contends that manifest data can provide valuable quantitative descriptors of taxi travel. This thesis attempts to describe taxi travel by quantifying trip characteristics; the shortcomings of using manifest data are discussed and the results are reported. The taxi operations results are then compared for weekend and weekday travel and also for airport and non-airport bound travel. Several key differences between these groups of taxi trips are discussed.
Next, an investigation of the relationship between mass transit facilities and taxi travel is conducted. Because taxis provide a complementary yet competing public transportation service to mass transit, it is hypothesized that examining the proximity to transit options and the timing of taxi trips can provide insight to the perceived gaps in mass transit services. However, the data show that simply examining geographic or temporal characteristics of taxi trips does not define clear relationships between transit facilities and taxi use. Instead, the results suggest that other variables such as land use and vehicle access may hold a greater influence over the generation of taxi trips.
Despite the difficulty in using manifest data to determine gaps in transit, the data collected by taxi regulators could have numerous applications for planners. Possible applications for the type of taxi data used in this research are explored and a potential data flow for agencies is proposed.Master of Science
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Grose, Michael David. "A system identification technique for predicting transient operation of gas turbine engines". Thesis, Virginia Tech, 1996. http://hdl.handle.net/10919/44491.
Texto completoResumen
A method for developing transient, predictive models of gas turbine engine performance using system identification techniques in conjunction with test cell data has been successfully demonstrated. Test cell data were obtained for both transient and steady-state operation from two F402-RR-406A USMC AV-8B engines at the Naval Aviation Depot (NADEP), Cherry Point, North Carolina.
One engine was run to gather a single set of steady-state data consisting of 24 subsets of five seconds of data. The other engine was run to obtain two sets of transient data, recorded at three different rates of engine acceleration for each set. The acceleration rates of 3, 25, and 100 degrees of throttle per second were preset in the test cell controls. These rates correspond to the angular velocity of the fuel throttle during an acceleration. Each of these six transient test runs consisted of 25 seconds of data. Data were captured at a rate of five Hertz over the engine operating range from idle (26% Low Pressure spool speed) to full military power (105% LP spool speed) for all cases.
A BASIC code developed at the NADEP required significant modification before it could be used to reduce the data. The modified code generated engine operating points consisting of mass flow rate, total pressure ratio, spool speed, and rate of acceleration for the inner fan, outer fan, and high pressure compressor. Finally, a multivariate regression technique using the SAS language was developed in cooperation with the Virginia Tech Statistical Consulting Center. This technique was used to generate a closed-form model of each component capable of predicting operating points at spool speeds and acceleration rates intermediate to those measured.
Master of Science
40
Plotnikov, Valeri. "An Analysis of Fare Collection Costs on Heavy Rail and Bus Systems in the U.S". Diss., Virginia Tech, 2001. http://hdl.handle.net/10919/29052.
Texto completoResumen
In this research, an effort is made to analyze the costs of fare collection on heavy rail and motorbus systems in the U.S. Since existing ticketing and fare collection (TFC) systems are major elements of transit infrastructure and there are several new alternative TFC technologies available on the market, the need to evaluate the performance of existing TFC systems arises. However, very little research has been done, so far, to assess impacts of TFC technologies on capital and operating expenses in public transit. The two objectives of this research are: (1) to formulate a conceptual evaluation framework and a plan to assess the operating costs of existing TFC systems in transit and (2) to analyze the operating expenses associated with existing TFC systems on heavy rail and motorbus transit in the U.S. with the aid of the evaluation framework and plan.
This research begins with a review of the current state of knowledge in the areas of transit TFC evaluation, the economics of public transit operations, and fare collection practices and technologies. It helps to determine the scope of work related to assessment of TFC operating costs on public transit and provides the basis for the development of a conceptual evaluation framework and an evaluation plan. Next, this research presents a systematic approach to define and describe alternative TFC systems and suggests that the major TFC system determinants are payment media, fare media, TFC equipment, and transit technology (mode). Following this is the development of measures of effectiveness to evaluate alternative TFC systems. These measures assess cost-effectiveness and labor-intensiveness of TFC operations. The development of TFC System Technology Index follows. This Index recognizes the fact that TFC systems may consist of different sets of TFC technologies both traditional and innovative. Finally, this research presents statistical results that support the hypothesis that TFC operating costs are related to transit demand, transit technology (mode) and TFC technologies. These results further suggest that: (1) TFC operating costs per unlinked passenger trip on heavy rail systems are higher than on motorbus systems and (2) TFC operating costs per unlinked passenger trip tend to increase as the use of non-electronic fare media increases. Actions for further research are also recommended.Ph. D.
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Chartier, Sébastien [Verfasser]. "SiGe HBT ICs with high operational to transit frequency ratio: design and design re-use / Sébastien Chartier". Ulm : Universität Ulm. Fakultät für Ingenieurwissenschaften und Informatik, 2011. http://d-nb.info/1016718497/34.
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Zhou, Gordon. "Machine Learning-Based Cost Predictive Model for Better Operating Expenditure Estimations of U.S. Light Rail Transit Projects". Thesis, The George Washington University, 2021. http://pqdtopen.proquest.com/#viewpdf?dispub=28157527.
Texto completoResumen
Inaccurate forecasts of operating expenditures during the planning phase for new Light Rail Transit (LRT) projects in the United States underestimated future costs by up to 45% (Pickrell, 1989). When operating expenditures exceeded projected levels, local transit agencies often reduced public transit services to operate within their respective annual budgets. Therefore, it is imperative for transit agencies to produce reasonably accurate planning estimates to secure sufficient funding to support future operations, maintenance, and service delivery associated with LRT systems. The research aimed to develop a more accurate LRT operating expenditure predictive model to be used during the planning stage. Traditional statistical analysis and various machine learning-based algorithms were utilized with input from 22 LRT systems in the United States spanning between 2008 to 2018 from various U.S. governmental public databases. This praxis extended the current state of practice that relied primarily on sum of unit-cost estimates (also known as the unit-cost method) which generally failed to produce accurate forecasts due to lack of engineering details at the planning stage. Existing research attempted to develop regression-based methodologies using system-based attributes but did not substantially increase prediction accuracy from using the unit-cost method. The research improved current practices and research by having developed a more accurate and replicable machine learning-based predictive model using available geographic, socio-economic and LRT system-related variables.
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Karimishad, Amir. "Transient stability-constrained load dispatch, ancillary services allocation and transient stability assessment procedures for secure power system operation". University of Western Australia. Energy Systems Centre, 2008. http://theses.library.uwa.edu.au/adt-WU2009.0028.
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[Truncated abstract] The present thesis is devoted to the development of new methods for transient stability-constrained optimal power flow, probabilistic transient stability assessment and security-constrained ancillary services allocation. The key objective of the thesis is to develop novel dispatch and assessment methods for power systems operation in the new environment of electricity markets to ensure power systems security, particularly transient stability. A new method for economic dispatch together with nodal price calculations which includes transient stability constraints and, at the same time, optimises the reference inputs to the Flexible AC Transmission System (FACTS) devices for maintaining power systems transient stability and reducing nodal prices is developed. The method draws on the sensitivity analysis of time-domain transient stability simulation results to derive a set of linearised stability constraints expressed in terms of generator active powers and FACTS devices input references. '...' The low computing time requirement of the two-point estimate method allows online applications, and the use of detailed power systems dynamic model for time-domain simulation which offers high accuracy. The two-point estimate method is integrated in a straightforward manner with the existing transient stability analysis tools. The integrated software facility has potential applications in control rooms to assist the system operator in decision making process based on instability risks. The software system when implemented on a cluster of processors also makes it feasible to re-assess online transient stability for any change in system configuration arising from switching control. The method proposed has been tested on a representative power system and validated using the Monte Carlo simulation. In conjunction with the energy market, by which forecasted load demand is met by generator dispatch, ancillary services are required in relation to control for secure system operation and power quality. The final part of the thesis has a focus on the key aspect of allocating these ancillary services, subject to an important constraint that the dispatch of the ancillary services will not impair the system security achieved in the load dispatch. With this focus and requirement, the thesis develops a new dispatch formulation in which the network security constraints are represented in the optimal determination of generator active power schedule and allocation of ancillary services. Contingencies considered include power demand variations at individual load nodes from the values specified for the current dispatch calculation. The required changes in generator active powers to meet the new load demands are represented by additional control variables in the new dispatch formulation which augment those variables in the traditional OPF dispatch calculation. Based on the Lagrange function which includes the extended set of security constraints, the formulation derives the optimality condition to be satisfied by the dispatch solution, together with the marginal prices for individual ancillary service providers and LMPs. The effects of the security constraints are investigated and discussed. Case studies for representative power systems are presented to verify the new dispatch calculation procedure.
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Westlund, Anders. "Simplified models for emission formation in diesel engines during transient operation". Doctoral thesis, KTH, Förbränningsmotorteknik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-33292.
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The work presented in this thesis is the result of the KTH CICERO project “Dynamic Engine Performance” in which the main objective was to develop simple models foremission formation. The demand for such models is increasing, mainly due to the tightening emission legislation for diesel engines which has lead to more complex engines and thereby more laborious development and calibration processes. Simple emission models can be a valuable tool during the development phase, e.g. when used with models for gas exchange - and after-treatment systems, and for precalibration of the engine control settings. Since engines in automotive application typically work under dynamic load, the main prerequisites were that the models should be comprehensive enough to handle the extreme conditions that can occur in engines during load transients but still simple enough to be used for calibration. Two main approaches have been used; one where the combustion and emission formation processes were modeled from the flame front and downstream using equilibrium chemistry. In the other approach, the entire mixing/entrainment process was modeled and emission formation was modeled with kinetic chemistry. Both approaches were found to meet the requirements but had different advantages; the first, simpler approach had shorter calculation time while the latter was more comprehensive and required less tuning. The latter also resulted in a model for heat release rate which can be useful as a stand-alone model and allows the emission models to be used for untested conditions. Another objective in this project was to identify techniques/instruments that can be used for emission measurements during transient operation since these are essential for understanding of emission formation in these conditions and as validation data for the emission models.QC 20110502
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Cooper, Erin Marie. "PLANNING FOR STOP SPACING UNDER THE SAN FRANCISCO MUNICIPAL TRANSPORTATION AGENCY BUS STOP CONSOLIDATION PROPOSAL". DigitalCommons@CalPoly, 2010. https://digitalcommons.calpoly.edu/theses/308.
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The purpose of this report was to analyze the elements of a bus stop consolidation program for the San Francisco Municipal Transportation Agency (SFMTA). This research shows that increasing stop spacing distances increases walking distances, but in places with high transit and stop density, most access distances will not be beyond a five to ten minute walk. In general, European cities with high transit mode shares recommend stops every 1300 feet. American guidelines recommend stops between approximately 800 to 1300 feet. According to the literature review, fewer stops can lead to a more reliable service. Time savings on the route also translate into significant cost savings for the agency. This paper presents a methodology for creating stop elimination proposals based on factors such as ridership, transfer points, and existing bus shelters or infrastructure. Public input can help to determine which bus stops are key locations. This methodology was used to propose stop consolidation for one bus route in San Francisco: Route 1 California Inbound. The route was then evaluated based on information from the literature review. The yearly savings can be as much as $340,000 to $930,000 per route.
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Gwebu, Excellent Zibhekele. "A methodology for integrated thermofluid modelling of radiant superheaters in steady state and transient operations". Doctoral thesis, Faculty of Engineering and the Built Environment, 2019. http://hdl.handle.net/11427/30367.
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Critical components in coal-fired power plants such as final superheater heat exchangers experience severe conditions associated with high metal temperatures and high temperature gradients during base load and transient operations. Such adverse conditions could significantly reduce the life span of the components, especially due to the requirement of greater plant flexibility that is an essential part of the global power system transformation. Integrated thermofluid process models can be employed to obtain a better understanding of the relationship between the operational conditions and the metal temperatures. Thus, a methodology was developed to model radiant superheater heat exchangers in steady state and transient operations. The methodology is based on a network approach which entails solving the transient one-dimensional forms of the conservation equations for mass, energy and momentum. The model building blocks account for the convective thermal resistance on the steam side, the conductive thermal resistances of the tube wall and scaling or fouling on the tube walls, as well as the convective and radiative thermal resistances and direct radiation on the flue gas side. The model captures the physical layout of the tube passes in a tubesheet via the arrangement of the network building blocks. It is also possible to connect tubesheets together across the width of the boiler as per the arrangement in a real plant. The modelling methodology was first used to develop a process model of a convective cross-flow primary superheater heat exchanger with complex flow arrangement. The dual-tube 12-pass superheater was discretized along the flue gas flow path as well as along the steam flow path. The model was qualitatively validated using real plant data from literature and for reference purposes also systematically compared to conventional lumped parameter models. The ability of the model to analyse the effect of ramp rate during load changes on the tube metal temperature was demonstrated, as well as the ability to determine the maldistribution of flow and temperature on the steam and flue gas sides. The methodology was also applied to model a U-shaped radiant superheater heat exchanger. Due to the challenges associated with obtaining comprehensive real plant data in an industrial setting, a validation methodology was proposed that is based on a combination of plant design C-schedules and a boiler mass and energy balance, as well as limited plant measurements. The consistent comparisons with C-schedule data provide evidence of the validity of the model, which was further demonstrated via the comparisons with real plant data. The model allows prediction of the steam mass flow and temperature distribution going into the outlet stub headers as well as the main outlet headers for different inlet flow and temperature distributions on the steam and flue gas sides. These results were compared to detail real-plant measurements of the outlet header temperatures. The model also allows prediction of the metal temperatures along the length of the tubes which cannot readily be measured in the plant. The model was applied to demonstrate the impact of different operational conditions on the tube metal temperatures. Such integrated process models can be employed to study complex thermofluid process phenomena that may occur during intermittent, transient and low load operation of power plants. In addition, such models could be useful for predictive and preventative maintenance as well as online condition monitoring.
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Gu, Yahong. "Integrating a Regional Planning Model (TRANSIMS) With an Operational Model (CORSIM)". Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/31289.
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TRANSIMS is a disaggregate, behavioral, regional transportation planning package developed by Los Alamos National Laboratory (LANL) under funding from US DOT, EPA, and Department of Energy. It is an integrated system of travel forecasting models designed to give transportation planners accurate, complete information on traffic impacts, congestion, and pollution by simulating on a second-by-second basis the movements of every person and every vehicle through the transportation network of a large metropolitan area. This regional microsimulation approach provides a better assessment of the performance of a large network than the current link performance functions utilized in the current planning procedures. On the other hand, their microsimulation approach on a regional scale requires a lot of data that may not be readily available, and utilize a low fidelity microsimulation in order to make it operational. Some agencies may be interested in performing a more detailed investigation of traffic patterns within a sub area, such as the downtown area. The author implemented a subarea focusing methodology within TRANSIMS and also developed an interface that allows the investigator to use a high-fidelity, small-size network efficient traffic operational software package â CORSIM to perform sub area traffic operational analysis with demand and network extracted from applications of TRANSIMS. This methodology will allow TRANSIMS to take advantage of higher fidelity models for sub-network analysis and allow CORSIM to use planning inputs such as individual 24 hour travel activities and trip chains. An evacuation model is also built and applied to Virginia Tech main campus, Blacksburg, VA to evaluate this sub area focusing methodology.Master of Science
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Thornton, Matthew Jaeger. "Modal vehicle activity on freeways and freeway onramps : an assessment of the oxides of nitrogen emissions impacts resulting from changes in vehicle operating mode due to ramp metering systems". Diss., Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/20785.
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Fisher, Ian Randell. "Transit innovations in British Columbia: 1988-98 integration, intermodal linkages and institutional co-operation". Thesis, 1998. http://hdl.handle.net/2429/8084.
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BC Transit, a provincial Crown Corporation operates and administers
conventional, fixed-route public transit services in British Columbia's major metropolitan
centres of Vancouver and Victoria and in 24 smaller communities across the province.
BC Transit service is available to 76% of the province's residents.
BC Transit has been successful in providing innovative services that respond to
community needs. Some of these innovations include the introduction of lift-equipped
and low-floor buses to improve accessibility, the use of bike racks and lockers to
integrate transit with cycling, the integration of school bus and transit services to build
transit ridership and improve efficiency, and the targeting of the post-secondary student
market with special services and discounted fares. The introduction of innovative services
to the non-metropolitan areas of the province has been facilitated by BC Transit's
Municipal Systems Program and the three-way partnerships between BC Transit, local
governments, and operating companies that it provides. Much of the planning for this
program is done by BC Transit staff in Victoria, allowing for the easy transfer of
experience between systems.
A key area for future transit innovations in B.C. is in the creation of a provincewide
public transportation system with integrated services and information. This would
involve the creation of regional transit services in areas where development is coalescing
into continuous corridors, rather than in discrete settlements.
Although BC Transit has been successful in introducing a range of innovative
services around the province, questions remain as to whether BC Transit's general
service provision strategy is as cost-effective and accountable as possible. The current
funding and governance arrangements in the province have created a situation that is
weak on local accountability and which may perpetuate the provision of uneconomic
services. Further research is needed to fully address this issue.
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Wu, Jeng-Ru y 吳政儒. "Long-term Operation Programming and Dynamic Dispatching Operation Modeling for Intelligent Multi-mode Transit System". Thesis, 2006. http://ndltd.ncl.edu.tw/handle/51937457027784532372.
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碩士國立交通大學
交通運輸研究所
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Determining dynamic headways for correctly identifying passenger demands and quickly responding to those needs with Intelligent Multi-mode Transit System (IMTS) operations control strategies is vital to the development of advanced public transportation systems in urban areas. The proposed model primarily involves two levels of functionality:(1) long-term operation programming utilizing multi-objective programming methods, and (2) identification of service strategies coupled with the associated bus service segments using dynamic dispatching operation model in response to variances in passenger demand attributes. The numerical results significantly reveal the potential advantages of the proposed methodology. Particularly, the travel time can be reduced by 51.6%, compared to the existing operational performance in the specific case studied. We expect that this study can make available the proposed method with benefits not only for programming IMTS long-term operations, but also for deciding dynamic dispatching strategies in a comprehensive extent.