Academic literature on the topic 'Greenshields model'
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Journal articles on the topic "Greenshields model"
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Rakha, Hesham, and Brent Crowther. "Comparison of Greenshields, Pipes, and Van Aerde Car-Following and Traffic Stream Models." Transportation Research Record: Journal of the Transportation Research Board 1802, no. 1 (January 2002): 248–62. http://dx.doi.org/10.3141/1802-28.
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Three car-following models were compared: the Greenshields single-regime model, the Pipes two-regime model, and a four-parameter single-regime model that amalgamates both the Greenshields and Pipes models. The four-parameter model proposed by Van Aerde and Rakha is less known but is currently implemented in the INTEGRATION 2.30 software. The Greenshields and Pipes models were considered because they represent state-of-the-practice models for several types of microscopic and macroscopic software. The Greenshields model is widely used in macroscopic transportation planning models. In addition, the Pipes model is implemented in a number of microscopic traffic simulation models including CORSIM and VISSIM. Steady-state car-following behavior is also related to macroscopic traffic stream models to develop calibration procedures that can be achieved using macroscopic loop detector data. The study concluded that the additional degree of freedom that results from including a fourth parameter (Van Aerde model) overcomes the shortcomings of the current state-of-the-practice traffic stream models by capturing both macroscopic and microscopic steady-state traffic behavior for a wide range of roadway facilities and traffic conditions. Also developed was a procedure for calibrating the Pipes car-following model using macroscopic field measurements that can be obtained from loop detectors. Although this calibration procedure does not overcome the inherent shortcomings of the Pipes model, it does provide an opportunity to calibrate the CORSIM and VISSIM car-following behavior to existing roadway conditions more efficiently and without the need to collect microscopic traffic data.
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Huang, Jingru, Yan Wang, and Mei Han. "Fast L2 Calibration for Inexact Highway Traffic Flow Systems." Electronics 11, no. 22 (November 12, 2022): 3710. http://dx.doi.org/10.3390/electronics11223710.
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Transportation systems need more accurate predictions to further optimize traffic network design with the development and application of autonomous driving technology. In this article, we focus on highway traffic flow systems that are often simulated by the modified Greenshields model. However, this model can not perfectly match the true traffic flow due to its underlying simplifications and assumptions, implying that it is inexact. Specifically, some parameters affect the simulation accuracy of the modified Greenshields model, while tuning these parameters to improve the model’s accuracy is called model calibration. The parameters obtained using the L2 calibration have the advantages of high accuracy and small variance for an inexact model. However, the method is calculation intensive, requiring optimization of the integral loss function. Since traffic flow data are often massive, this paper proposes a fast L2 calibration framework to calibrate the modified Greenshields model. Specifically, the suggested method selects a sub-design containing more information on the calibration parameters, and then the empirical loss function obtained from the optimal sub-design is utilized to approximate the integral loss function. A case study highlights that the proposed method preserves the advantages of L2 calibration and significantly reduces the running time.
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Lucky Tulus Pribadi. "Studi Hubungan Volume, Kecepatan dan Kerapatan pada Ruas Jalan Gatot Subroto Kota Cimahi." Jurnal Teknik: Media Pengembangan Ilmu dan Aplikasi Teknik 3, no. 1 (August 28, 2020): 233–39. http://dx.doi.org/10.26874/jt.vol3no1.235.
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Arus lalu lintas merupakan interaksi yang unik antara pengemudi, kendaraan, dan jalan. Tidak ada arus lalu lintas yang sama bahkan pada keadaan yang serupa. Sehingga arus pada suatu ruas jalan tertentu selalu bervariasi. Walaupun demikian diperlukan parameter yang dapat menunjukkan kondisi ruas jalan, atau yang akan dipakai untuk desain. Parameter tersebut antara lain adalah volume, kecepatan dan kerapatan.
Hubungan antara volume, kecepatan dan kerapatan sering digunakan sebagai dasar dalam pengelolaan arus lalu lintas pada suatu jalan raya. Untuk itu perlu dilakukan suatu studi mengenai ketiga parameter ini sehingga hasil studi dapat memberikan gambaran yang saling terkait antara ketiga parameter tersebut. Hasil analisis dari studi berupa model matematis yang dikembangkan berdasarkan hubungan dasar volume sama dengan kecepatan kali kerapatan atau dalam bentuk persamaan V = D.Us.
Terdapat banyak model dalam menyatakan hubungan antara volume, kecepatan dan kerapatan. Tiga diantaranya adalah model Greenshields, Greenberg dan Underwood. Greenshields mendasarkan modelnya pada asumsi hubungan kecepatan dan kerapatan merupakan hubungan linier. Greenberg beranggapan arus lalu lintas dapat dianalogikan sebagai arus fluida. Hubungan kecepatan dan kerapatan pada model Greenberg dengan demikian merupakan hubungan logaritmik. Pada model Underwood, model yang disusun berdasarkan teorinya dari hasil penelitian kecepatan dan kerapatan dimana kedua parameter ini memiliki hubungan eksponential.
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Mukhlis, Mukhlis. "HUBUNGAN KECEPATAN, KEPADATAN DAN VOLUME LALU LINTAS DENGAN MODEL GREENSHIELDS (STUDI KASUS JALAN DARUSSALAM LHOKSEUMAWE)." TERAS JURNAL 3, no. 2 (November 6, 2017): 148. http://dx.doi.org/10.29103/tj.v3i2.40.
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<p>Jenis kendaraan lalu lintas yang melintasi Jalan Darussalam Kota Lhokseumawe terdiri dari mobil penumpang, mobil barang, becak dan sepeda motor. Banyaknya kendaraan yang melewati jalan tersebut sangat dipengaruhi oleh banyaknya fasilitas-fasilitas umum yang digunakan oleh masyarakat, seperti pertokoan, mini market, sekolah, pertamina, perkantoran, dan lain-lain. Dalam merepresentasikan hubungan matematis kecepatan, kepadatan dan volume lalu lintas pada Jalan Darussalam Kota Lhokseumawe digunakan model Greenshields. Pengamatan untuk penelitian dilakukan pada haris Senin, Jum'at dan Minggu mulai pukul 07.00 WIB sampai dengan pukul 19.00 WIB. Bentuk matematis hubungan antara Kecepatan dan Kepadatan untuk hari Senin adalah S - D = 42,37 - 0,9611 D, sedangkan untuk hari Jum'at adalah S - D = 22,915 + 0,8513 D dan untuk hari Minggu adalah S - D = 45,5254 - 0,9922 D. Bentuk matematis hubungan antara Volume dan Kepadatan untuk hari Senin adalah V - D = 42,37 D - 0,9611 D², sedangkan pada hari Jum'at adalah V - D = 22,915 D - 0,8513 D², dan untuk hari Minggu adalah V - D = 45,5254 D - 0,9922 D². Bentuk matematis hubungan antara Volume dan Kecepatan untuk hari Senin adalah V - S = 44,0849 S - 0,9611 S², sedangkan untuk hari Jum'at adalah V - S = -26,9177 S + 1,1747S², dan untuk hari Minggu adalah V - S = 45,8821 S - 1,0078 S².</p><p><br /><strong>Kata kunci:</strong> Kecepatan, kepadatan, Volume Lalu lintas, Model Greenshields</p>
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Juanda, Ari, Muhammad Isya, and Noer Fadhly. "Hubungan Volume, Kecepatan Dan Kepadatan Dengan Model Greenshields, Greenberg, Dan Underwood Pada Ruas Jalan Luar Kota Kawasan Gunung Geurutee." Jurnal Arsip Rekayasa Sipil dan Perencanaan 2, no. 4 (December 10, 2019): 286–93. http://dx.doi.org/10.24815/jarsp.v2i4.14945.
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In Indonesia, Karl-L Bang research in 1994 on the relationship between traffic parameters was included in the Indonesian Road Capacity Manual 1997. The research has undergone many changes between 1994 and 2018 in the growth of traffic that may affect traffic flow and volume, speed and density all urban roads, roads outside the city in an area, In Aceh studies have also been conducted into the relationship between traffic parameters on different roads. On this basis, it is very necessary to know the characteristics of traffic flows that occur on the Banda Aceh - Meulaboh section 65 + 450 is located in Aceh Jaya Regency, in the province of Aceh. Given that this road is located in an extremely mountainous area, where there are many very steep curves and ravines and rocks on the cliff side of the road. Analysis using models Greenshields, Greenberg, and Underwood. The results of the study show that the Greenshields model is the most satisfying compared to the Greenberg model and the Underwood model with a coefficient of determination (R2) greater than 0.88. The model is in accordance with the traffic conditions on the Outer City Road. Then the traffic flow obtained can not reach optimum conditions, namely in a stable traffic flow condition. The relationship between speed and density (S-D) with the model equation is S = 36,525 - 0,815 D; The volume-density (V-D) relationship with the model equation is V = 36,525 D - 0,815 D2; The relationship of volume - speed (V-S) with the model equation is V = 44,835 S - 1,228 S2
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Efendi, Jauhari, and Rosehan Anwar. "THE COMPARATIVE ANALYSIS OF THE PERFORMANCE OF TRAFFIC FLOW USING MKJI METHOD, GREENSHIELDS MODEL, GREENBERG, AND UNDERWOOD ON THE WAY THE BASIS OF ULIN BANJARBARU KM.23 BANJARBARU (STA 23+450 - STA 23+650)." CERUCUK 3, no. 1 (September 19, 2019): 53. http://dx.doi.org/10.20527/crc.v3i1.1104.
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Traffic flow is one of the components that cannot be integral part with other components such as social activity, economic, cultural, population and land use patterns. Along with the growth of traffic flow increased rapidly, then there would be the density of traffic flow. This is because the density of the capacity of the motor vehicle on the street are very much, this can lead to delays.Three model approach through traffic Greenshields model, Greenberg, Underwood Manual and the capacity of the way Indonesia (MKJI) 1997 provide guidance to get the level of service of the road from a roads.The model equation for the flow of Banjarmasin to Banjarbaru namely model greenberg with equation y = -39,9ln(x)+179,7 and value of R of 0,7312 with maximum volume 1326,38 smp/hour, while for the current Banjarbaru to Banjarmasin obtained similarities with Greenberg Model, y = -14,32ln(x) + 102,23 and value of R of 6638,38 obtained when the volume of the maximum of 460 smp/hour.Based on the prediction that done, obtained the result that in the year 4 and year 5 the level of services in the way of Ahmad Yani Km.32 Banjarbaru located on the category of class E and F. So the need to be done so that the level of services can be increased and become better.Key Words: Greenshields, Greenberg, Underwood, MKJI, prediction.
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Shlayan, Neveen, Kiran Challapali, Dave Cavalcanti, Talmai Oliveira, and Yong Yang. "A Novel Illuminance Control Strategy for Roadway Lighting Based on Greenshields Macroscopic Traffic Model." IEEE Photonics Journal 10, no. 1 (February 2018): 1–11. http://dx.doi.org/10.1109/jphot.2017.2782801.
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Khan, Zawar Hussain, Thomas Aaron Gulliver, and Waheed Imran. "A Macroscopic Traffic Model Based on the Safe Velocity at Transitions." Civil Engineering Journal 7, no. 6 (June 1, 2021): 1060–69. http://dx.doi.org/10.28991/cej-2021-03091710.
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The increasing volume of vehicles on the road has had a significant impact on traffic flow. Congestion in urban areas is now a major concern. To mitigate congestion, an accurate model is required which is based on realistic traffic dynamics. A new traffic model is proposed based on the conservation law of vehicles which considers traffic dynamics at transitions. Traffic alignment to forward conditions is affected by the time and distance between vehicles. Thus, the well-known Lighthill, Whitham, and Richards (LWR) model is modified to account for traffic behavior during alignment. A model for inhomogeneous traffic flow during transitions is proposed which can be used to characterize traffic evolution. The performance of the proposed model is compared with the LWR model using the Greenshields and Underwood target velocity distributions. These models are evaluated using the Godunov technique and numerical stability is guaranteed by considering the Courant, Friedrich, and Lewy (CFL) condition. The results obtained show that the proposed model characterizes the flow more realistically, and thus can provide better insight into traffic behavior for use in controlling congestion and pollution levels, and improving public safety. Doi: 10.28991/cej-2021-03091710 Full Text: PDF
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Arrang, Abdias Tandi. "HUBUNGAN KECEPATAN, VOLUME DAN KEPADATAN LALULINTAS DI JALAN DR. RATULANGI (DEPAN CITY MARKET PALOPO) MENGGUNAKAN MODEL GREENSHIELDS." Journal Dynamic Saint 4, no. 2 (March 18, 2020): 803–10. http://dx.doi.org/10.47178/dynamicsaint.v4i2.882.
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Terbangunnya City Market Palopo sebagai salah satu pusat perbelanjaan di Kota Palopo memberikan dampak pada bertambahnya volume lalulintas di Jalan Dr. Ratulangi, di mana jalan tersebut merupakan salah satu jalan utama yang menjadi penghubung antara Makassar sebagai ibu kota Propinsi Sulawesi Selatan ke daerah seperti Luwu Utara, Luwu Timur bahkan ke Propinsi Sulawesi Tengah, dan Sulawesi Tenggara. Adanya peningkatan volume lalu lintas akan menyebabkan berubahnya perilaku lalu lintas. Secara teoritis terdapat hubungan yang mendasar antara volume (flow) dengan kecepatan (speed) serta kepadatan (density). Penelitian dilakukan dengan survey arus, kecepatan dan mengambil data geometrik pada lokasi penelitian. Data kemudian diolah dan dianalisis dengan metode Greeshields. Dari analisis tersebut diperoleh persamaan hubungan antara volume dan kepadatan adalah Q = 30.766 D – 0.081 D2, sementara persamaan hubungan antara kecepatan dan kepadatan adalah S =3 0.766 – 0.081 D dan persamaan hubungan antara kecepatan dan volume adalah Q = 377.144 – 12.258 S2. Analisis menunjukkan bahwa grafik hubungan antara arus, kecepatan dan kepadatan sesuai dengan model Greenshields
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Wu, Zhipeng. "Study on regional road network planning based on time and noise integrated resistance function." INTER-NOISE and NOISE-CON Congress and Conference Proceedings 265, no. 7 (February 1, 2023): 25–31. http://dx.doi.org/10.3397/in_2022_0006.
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To rationally reduce traffic noise emission from road network from the perspective of planning, a regional traffic flow distribution method combining time and noise integrated resistance function is proposed, and the method is applied in a typical region to verify its reasonability and practicability. Firstly, according to Greenshields model, the relationship among three traffic parameters (velocity, density and flow) is described, and combined with a line-source emission model of traffic noise, a univariate noise prediction model based on flow is established. Then, with the establishing of the traffic noise resistance function, an integrated resistance model considering traffic noise impact and travel time impact is proposed, which is used for traffic flow distribution while in the road network planning process. Finally, the network planning is realized utilizing the proposed method considering traffic noise. A network planning case in a typical region shows that the method can effectively reduce the noise emission of the regional network, which has practical value in traffic environment control.
Dissertations / Theses on the topic "Greenshields model"
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Koutný, Vladimír. "Multiagentní systém pro simulaci a analýzu dopravního provozu." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2010. http://www.nusl.cz/ntk/nusl-218373.
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This diploma thesis deals with an oriented graph processing applying a multi-agent system designated for traffic simulation. The thesis was written as a research study. Based on the study, a simulation environment was created able to respond to various stimuli. Meant as the agents, there are vehicles and their drivers that have various features, based on which they respond to the given stimuli. Communication is conducted via a so-called super-agent that monitors all action on the map and passes this information on particular agents. The agents are able to respond in advance to traffic jams (closures, accidents). In such situations, an algorithm designated for a new route finding is conducted. Besides the controlled ones, there can operate on the map also agents simulating common traffic.
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Alnajajreh, Abedelkareem J. M. "A mesoscopic simulation model for dynamic network loading and spillback queuing assessment in a multiclass environment." Doctoral thesis, 2020. http://hdl.handle.net/11589/188500.
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Traffic flow modelling is the most significant component undertaken by the static and the dynamic network loading (DNL) models in the traffic assignment. Dynamic network loading models represent a non-linear relationship between each link flow and its path flow, as they are the fundamental element in estimating the dynamic interaction between demand and supply in oversaturation condition. Moreover, the solution for dynamic network loading problems is necessary for generating the dynamic traffic assignment (DTA) models. Dynamic models can be characterized according to the simulation details level: microscopic, macroscopic or mesoscopic models. Accordingly, microscopic simulation models fit well in small-scale planning determinations with interest addressed to entities’ interactions as these models describe the interaction between vehicles, and between vehicle themselves and transportation infrastructure. Instead, macroscopic models are capable of the general planning purposes adopting large-scale simulations. As they assume the traffic as a continuous fluid and the flow is subject to the congruency and to the continuity constraints. Finally, the mesoscopic approach simulates most of the entities at a high level, but activities and interactions at a low level of details. In this context, for a reasonable level of details, coupled with entities interaction information at once, mesoscopic models simulate each link considering the traffic as a set of continuous or discrete packets: a continuous packet is defined by its head and tail, conversely to the discrete packet which is defined by its head, regardless of the tail position. Many different aspects can be included within the dynamic network loading models such as the multiclass property. It includes the vehicular type in the mesoscopic simulation, which generates different dynamics on the same link considering more than one vehicle type at the same time. With this complication, once the supply becomes unable to meet the demand (oversaturation condition), evaluation of the queuing spillback is necessary to prevent excessive delays and to forecast the new trip travel time. For this aim, this thesis proposes a new dynamic network loading model which simulates traffic dynamics (speed, density, flow, queue, etc.) explicitly, through modelling the traffic flow considering a discrete mesoscopic simulation model in a multiclass environment. The proposed model is capable of using two speed-density relations to simulate flow dynamics: the Greenshields and the triangular-shaped fundamental diagram. FIFO rule holds between the vehicles in the same class and creeping speed is assumed to avoid circulation blockage in oversaturation conditions. Moreover, three vehicle classes (private car, bus, truck) have been considered in the simulation. The proposed model has been validated in undersaturation conditions by comparing model estimations with real observations collected by ATC sensors for Maliha Highway in the United Arab Emirates. For assessing the dynamic queue spillback, the proposed model has been applied to a simple network for easily assessing its capabilities in oversaturation conditions. Moreover, a comparison with a commercial traffic simulation software, Aimsun Next, has been carried out to evaluate the performance of the proposed model. The comparison has shown a relatively similar behaviour and simulation time for all classes in the case of using the triangular fundamental diagram relation but with much more fluctuation for the Aimsun model. On the contrary, using Greenshields relations provided the same behaviour but with much longer simulation time. As a result, the proposed model has presented the mesoscopic simulation in a more reliable way since Aimsun seems to include other microscopic characteristics in the mesoscopic traffic simulation like start-and-stop behaviour. Finally, it can be used with confidence as a tool to quantify the traffic dynamics of each class in oversaturation conditions including queue spillback. Keywords—congestion, flow propagation, Greenshields model, queue spillback, multiclass mesoscopic simulation.
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TSAI, YU-CHEN, and 蔡育成. "Analysis and Optimization of Traffic on Highway with Greenshield Model." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/74xd65.
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碩士國立高雄第一科技大學
電腦與通訊工程系碩士專班
105
Transport network in Taiwan is well developed. However the traffic in highway during rush hours often result in congestion due to the lack of enough facilities to guide drivers or provide traffic information in advanced. For providing better quality of service more advanced devices and sensors are required to collect more date such as speed, traffic flow, and capacity for further analysis and process as the information in intelligent transportation system. This thesis investigates the use of Greenshield's model by collecting traffic data in various sections of the Expressway for providing the travel time and traffic estimation. Sensor devices include loop coil, vehicle detection card, microprocessor and Ethernet photoelectric converter, which can collect real time data for establishing different Greenshield's models. We can obtain the required parameters in various conditions such that the optimum throughput can be reached through the Greenshield's model's velocity-density relationship and flow. In this thesis, a real-time algorithm for travel time estimation is proposed. We build a loop vehicle detector on each section to collect data such as traffic flow, speed and so on as travel time estimates. We transfer these data through the transport system to the Traffic Management Center database for further application in the Greenshield's model to establish the relationship between speed, density and free speed. Finally, these field data and Greenshield's model are obtained with an appropriate weighting factor for travel time estimates. And through the simulation results show that the Greenshield's model based on the real-time algorithm is effective, can provide accurate travel time estimates on Expressway, but also linked to the Intelligent Transportation System, providing Real-Time information to enhance the safety efficiency of the transport system and Comfort, reduce the impact of traffic on the environment.
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Huang, Chi-Nan, and 黃啟南. "Greenshield Model Based Travel Time Estimation for Traffic on Highway." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/3ewwg6.
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碩士國立高雄科技大學
電腦與通訊工程系
107
Intelligent Transportation System (ITS) improves vehicle traffic, driving safety, management efficiency, and service quality by applying advanced intelligent technologies in all kinds of transportation systems. Up to the present day, people can drive vehicles more safely and comfortably on roads with advanced vehicle control and safety systems, receive all kinds of traffic information for choosing routes, avoiding incident, and managing their travel. ITS is classified into several systems according to their functions. Among them, detecting traffic situations and then transmitting them to control center for developing traffic strategies is the major role of the advanced traffic management system. This also responses to public demand for reducing traffic congestions on freeways during rush hours in metro area that happens almost every day. The advanced traffic management system collects information such as traffic flow, speed, and concerned measures by taking advantage of various devices or equipment. With these data, it can carry out traffic control and transmit information to drivers and concerned departments. This study develops a scheme for the traffic management and travel time estimation on highway by implementing the Greenshield model according to the traffic data collected from the Tainan to Kaohsiung section of the National Highway No.1. Data collection was carried out by the roadside units. The unit consists of two devices: the terminal controller and roadside vehicle detector. Based on the data of traffic flows and vehicle speeds collected in different periods, the corresponding Greenshield model with related parameters is established. In each highway section, with the best traffic flow evaluated from the speed versus density curve of the Greenshield model and measures, the control center is able to improve the rush-hour traffic by following out speed control, signal control, incident management, and high occupancy vehicle control. This study also proposes an estimation scheme of the travel time according to the traffic flow of the Greenshield model and statistics data of vehicle speeds collected by the roadside unit. By applying the speed data on the speed versus density curve of the Greenshield model a reference speed is obtained. The estimated travel time is calculated through the weighted moving average with properly assigned weightings to the reference speed and statistical speed. Simulations show that the proposed scheme can achieve an accurate estimation result.
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Mei, Chung-Yueh, and 梅中粵. "Application of the Modified Greenshield’s Model to Vehicle Collision Avoidance Systems." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/24948733236747887774.
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碩士國立高雄第一科技大學
電腦與通訊工程研究所
103
Abstract Recently, due to the increase of the internet speed, the use of high-speed internet as an opportunity to collecting relevant traffic parameters for traffic safety prediction. With the global satellite positioning system (GPS) in its increasingly precise accuracy, the position of the vehicle can be used as a reference basis. For the train collision avoidance system, the use of wireless communication to perform communication between the vehicle to the vehicle, the vehicle to rail wayside and rail wayside to rail wayside. This thesis proposed three modified Greenshield, Greenberg and Underwood equations and related diagrams for computing the stopping distance used in the vehicle collision avoidance system. The first method converts the decrease speed in the Greenshield model into the increase speed. A similar method is applied to the Greenberg and Underwood, models with a fine-tuned constant so that the graphical curve has an intersection with the stopping distance. Then the original saturation density parameter is replaced by the stopping distance as the reference for stopping distance prediction. As the train speed is below the speed limit of the road, the original stopping distance curve is recommended. On the other hand, if the train speed is higher than the speed limit, the modified Underwood model is recommended for safety enhancement. In the simulation, the drivers’ reaction time and brake friction coefficient are taken into account as random variables, and the stopping distance is obtained from the arithmetic mean of two train’s stopping distances. To obtain different reference safety factors, we perform several simulations based on different real environments. The resultant different parameters can be used as reference for standard establishment in the future. Key words: Global positioning system (GPS); positive train control (PTC); stopping distance.
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Hsiao, Chih-yu, and 蕭智宇. "Travel Time Estimation Based on Greenshield''s Model for Freeway Inter-Vehicle Communications." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/27862868118135581720.
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碩士國立高雄第一科技大學
電腦與通訊工程研究所
103
In all traffic information, the main concern for drivers is the travel time. Information such as vehicle speed and traffic flow are all should be derived from the travel time. For predicting travel time, this paper proposed an algorithm based on the data collected from the loop vehicle detector on freeway and the Greenshield’s model between different exits in freeway. The relationship between speed-density free-flow velocity in the Greenshield’s model is utilized as an important parameter for travel time prediction. Different freeway sections have different Greenshield''s models. The driver on each section will select a proper model parameter as the reference for performing the estimation algorithm and updating the estimated travel time achieve real-time update feature. In this thesis, a real-time algorithm for travel time estimation is proposed. First, vehicle loop detector data are collected in each section as reference information for travel time estimation. Inter-Vehicle Communication is attained by the use of DSRC and VANETs. Second, the data from loop vehicle detectors are applied on the Greenshield''s model to establish the relationship between speed density and free velocity. These data are transmitted to the database in the traffic management center for further applications in vehicle-vehicle communications. Finally, a moving average algorithm is developed by taking into account the data from the loop vehicle detector and the Greenshield''s model and applying a proper weighting factor for performing the travel time estimation. Our simulation results show that the developed Greenshield’s model based real-time algorithm is effective and accurate for the travel time estimation on the freeway.
Book chapters on the topic "Greenshields model"
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Reddy, Sai Prasanna, Teja Tallam, and K. M. Lakshmana Rao. "Calibration of Pedestrian Flow Model Using Greenshield’s Macroscopic Stream Model for a Signalized Midblock." In Lecture Notes in Civil Engineering, 101–11. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-3662-5_10.
Full textConference papers on the topic "Greenshields model"
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Yun, Li, and Zhang Shengrui. "Analysis on Actual Capacity of Long Tunnel by Using Greenshields Model." In 2012 International Conference on Connected Vehicles and Expo (ICCVE). IEEE, 2012. http://dx.doi.org/10.1109/iccve.2012.56.
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Groll, Rodion, and Hans J. Rath. "On Eulerian Modeling of Microchannel Gas Flows Closing Higher Statistical Moments of Molecule Velocity." In ASME 2010 8th International Conference on Nanochannels, Microchannels, and Minichannels collocated with 3rd Joint US-European Fluids Engineering Summer Meeting. ASMEDC, 2010. http://dx.doi.org/10.1115/fedsm-icnmm2010-30212.
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High pressure gradient driven micro-channel flow modelling with very the high ratios of absolute pressure and temperature (see Agrawal et al. 2005 [1]) define the difference between physical and computational results using continuum approaches (see Maurer et al. 2003, Durst et al. 2006, Dongari et al. 2008 [3, 4, 8]). In the present paper this deviation of the computational results is explained by the statistical correlation of the molecular number density and the single molecule velocity inside a compressible gas flow. Classical solutions of Navier-Stokes equations do not satisfy the physical conditions of compressible, dilute molecular flows (see Brenner 2005, Greenshields and Reese 2007, Mizzi et al. 2008 [2, 6, 9]). Furthermore the consistent entropy production and the comparison between macroscopic physical values and the molecular diffusion closure are shown. Finally the computational results using this statistical model are compared with algebraic solutions verifying the thermodynamic consistence of the present statistical moment closure model.
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Groll, Rodion, Fabian Fastabend, and Hans J. Rath. "Modelling Transsonic Flows Through Ring-Shape Thruster Geometries With DSMC." In ASME 2012 10th International Conference on Nanochannels, Microchannels, and Minichannels collocated with the ASME 2012 Heat Transfer Summer Conference and the ASME 2012 Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/icnmm2012-73027.
Full textAbstract:
When modeling rarefied gas flows, continuous approximation is limited by the Knudsen regime. The presented cold gas thruster for space applications is investigated for pressure values lying between 10−2 and 103 Pa. It is comprised of a subsonic funnel region, a transsonic region consisting of a ring-shaped nozzle throat and a supersonic diffuser region. Diffusive and specular / mirror reflection is used to describe the behavior of particle/wall collision in the discrete model. Simulation results are compared both with experimental data and with numerical results computed using a finite-volume method. The transsonic flow through the nozzle throat shows very good agreement with experimental data. Simulation and experimental results emphasize the influence of various geometric factors like size and shape of the nozzle throat. Furthermore, differences in the acceleration behavior of Argon and Xenon are examined. Results of simulations utilizing the DSMC method [Bird, 1994, Stefanov et al., 2011] with diffusively reflecting boundary conditions present the best agreement with experimental data. Any deviation seen using the finite-volume method with no-slip boundary conditions can be explained by the equilibrium gas-state near the walls [Brenner, 2005, Greenshields et al., 2007]. The non-equilibrium approach produces lower velocity gradients near the wall, especially in wall regions with high levels of surface curvature.
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Al-Faris, Husam, and Mahmood Al-Obaidi. "Comparative Study of Traffic Flow Models: A Case study for Al-Doura Expressway in Baghdad City." In INTERNATIONAL CONFERENCE ON ARCHITECTURAL AND CIVIL ENGINEERING 2020. Cihan University-Erbil, 2021. http://dx.doi.org/10.24086/aces2020/paper.252.
Full textAbstract:
Speed, flow, and density are the most effectiveness traffic parameters. For the study area, all required speed-flow data were collected manually by special team using the necessary survey equipment from 11:00am-6:00pm during one week within different days for each direction of Al-Doura Expressway in Baghdad city. Greenshield Model (GSM) and Greenberg Model (GBM) have been analyzed using EXCEL software to compare the implementation results of the real data. The calibration of regression analysis studies were used and the statistical coefficient of person's correlation (R) and coefficient of determination (R2) were computed. It was found the following: For the direction of Baghdad greater bridge to Al-Rasheed camp, models according to GSM and GBM are us=110.84–0.37k and us=59.24ln(320.72/k) respectively. For the second direction, the models are us=64.04–0.10k and us=11.99ln(2937.5/k) respectively. All models are achieved strong correlation between variables ( between 0.88-0.98, and high R2 between 0.77-0.97). The models according to Greenberg ascertain better fit due to values between 0.95-0.98 and due to R2 values between 0.90-0.97 which are closest to 1.00 and these represent the coefficients for the first and second directions respectively. Finally, u0 and k0 at maximum flow have been considered based on GBM showing that the traffic capacity equal to 6990.08 and 12959.17 vph for the two sides. This mean that Al-Doura Expressway serve the study area with a 35-65 of directional split. This distribution of traffic between the two directions is nearly coincide with the distribution of the real data 34.6-65.4.