Relevant bibliographies by topics / Crest vertical curves

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  1. Journal articles
  2. Dissertations / Theses
  3. Book chapters
  4. Conference papers

Academic literature on the topic 'Crest vertical curves'

Author: Grafiati
Published: 4 June 2021
Last updated: 15 February 2022

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Journal articles on the topic "Crest vertical curves"

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Sun, Jian Cheng, and Chen Feng Chen. "Length Requirements for New Single-Arc Unsymmetrical Crest Vertical Curve for Highways." Advanced Materials Research 1065-1069 (December 2014): 755–59. http://dx.doi.org/10.4028/www.scientific.net/amr.1065-1069.755.

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Existing highway vertical curves may be grouped into two categories: symmetrical vertical curves and unsymmetrical vertical curves. In the past vertical curves design, parabolic arc was used as the vertical curve. This paper presents the new single-arc unsymmetrical vertical curve which is include only one cubic parabola. This curve has the gradual change of the rates of change in grade so that it can provide more comfort to the driver. This paper mainly presents the method by which to find the minimum length for a new single-arc unsymmetrical crest vertical curve based on the minimum sight distance . The discussion will be divided into two situations: the sight distance is longer than the curve length and the sight distance is not longer than the curve length.
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Hasan, Moudud, Tarek Sayed, and Yasser Hassan. "Influence of vertical alignment on horizontal curve perception: effect of spirals and position of vertical curve." Canadian Journal of Civil Engineering 32, no. 1 (February 1, 2005): 204–12. http://dx.doi.org/10.1139/l04-090.

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Several studies have shown that the perception of horizontal curves can be influenced by an overlapping vertical alignment. A previous two-phase study investigated the hypothesis that a horizontal curve appears flatter when overlapping with a vertical sag curve and sharper when overlapping with a vertical crest curve. The study concluded that the hypothesis was valid. The study also developed several statistical models to estimate the perceived radius of horizontal curves in a combined alignment. This study extends the earlier work by investigating the effect of additional geometric parameters on the perception. The parameters examined include the presence of spiral curves, the length of the spirals, and the position of the vertical curve midpoint relative to the horizontal curve. It was found that (1) driver misperception of the horizontal curvature increases as the radius of the horizontal curve increases, (2) the presence of a spiral curve affects driver perception of the horizontal curvature in the case of crest combination only, (3) the length of the spiral curve has no effect on the perception whether on crest or sag combinations, and (4) while the effect of the position of the vertical curve midpoint relative to the horizontal curve is not statistically significant, it seems that the perception problem appears to diminish as the positive offsets increases.Key words: highway geometric design, visual perception, combined alignment.
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Taignidis, Ioannis, and George Kanellaidis. "Required Stopping Sight Distance on Crest Vertical Curves." Journal of Transportation Engineering 127, no. 4 (August 2001): 275–82. http://dx.doi.org/10.1061/(asce)0733-947x(2001)127:4(275).

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Ko, Myunghoon, Dominique Lord, and Josias Zietsman. "Environmentally Conscious Highway Design for Crest Vertical Curves." Transportation Research Record: Journal of the Transportation Research Board 2270, no. 1 (January 2012): 96–106. http://dx.doi.org/10.3141/2270-12.

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Easa, Said M. "Improved speed-profile model for two-lane rural highways." Canadian Journal of Civil Engineering 30, no. 6 (December 1, 2003): 1055–65. http://dx.doi.org/10.1139/l03-021.

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The speed-profile model has been suggested as a valuable tool for evaluating geometric design consistency for two-lane rural highways with isolated and combined horizontal and vertical alignments. The model determines the operating speeds on the speed-change (SC) segment, which is the distance between speed-limiting curves. The speed-limiting curves are the horizontal curves and the limited sight-distance crest vertical curves on horizontal tangents, where the sight distance required by the design guides is not satisfied. The model assumes that deceleration begins where required, which implies that the next curve is visible when deceleration starts. This paper presents an extension to the speed-profile model to incorporate the effect of sight obstruction on operating speeds and deceleration rates. The SC segment may include nonlimited sight–distance crest vertical and sag vertical curves. These curves may present sight obstruction. A procedure to determine whether the sight line is obstructed is developed. If it does, simple formulas are applied for revising the operating-speed profile. The extended model is suitable for inclusion in the design consistency module of the interactive highway safety design model.Key words: speed profile, model, two-lane highways, alignments, design consistency.
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Hassan, Yasser. "Improved Design of Vertical Curves with Sight Distance Profiles." Transportation Research Record: Journal of the Transportation Research Board 1851, no. 1 (January 2003): 13–24. http://dx.doi.org/10.3141/1851-02.

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Design of vertical alignment is one of the main tasks in highway geometric design. This task requires, among other things, that the designer ensure drivers always have a clear view of the road so they can stop before hitting an unexpected object in the road. Therefore, the ability to determine the required and available stopping sight distance (SSD) at any point of the vertical alignment is essential for the design process. Current design guides in the United States and Canada provide simple analytical models for determining the minimum length of a vertical curve that would satisfy the sight distance requirement. However, these models ignore the effect of grade on the required SSD. Alternative approaches and models have also been suggested but cover only special cases of vertical curves. Two specific models were expanded to determine the required SSD on crest and sag vertical curves. By comparing profiles of available SSD and required SSD on examples of vertical curves, it was shown that current North American design practices might yield segments of the vertical curve where the driver’s view is constrained to a distance shorter than the required SSD. An alternative design procedure based on the models was developed and used to determine the minimum lengths of crest and sag vertical curves. Depending on the approach grade, these new values of minimum curve length might be greater than or less than values obtained through conventional design procedures. Design aids were therefore provided in tabular form for designers’ easy and quick use.
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Taiganidis, Ioannis. "Aspects of Stopping-Sight Distance on Crest Vertical Curves." Journal of Transportation Engineering 124, no. 4 (July 1998): 335–42. http://dx.doi.org/10.1061/(asce)0733-947x(1998)124:4(335).

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Fambro, Daniel B., Kay Fitzpatrick, and Charles W. Russell. "Operating Speed on Crest Vertical Curves with Limited Stopping Sight Distance." Transportation Research Record: Journal of the Transportation Research Board 1701, no. 1 (January 2000): 25–31. http://dx.doi.org/10.3141/1701-04.

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Horizontal and vertical elements of a highway are designed based on an assumed design speed. This concept was developed in the 1930s as a mechanism for designing rural alignments to permit most drivers to operate uniformly at their desired speed. In 1938, AASHO recognized that drivers select a speed influenced by the roadway environment instead of an assumed design speed. Recent research suggests that design speed is no longer the speed adopted by the faster group of drivers but that it has become a value used to establish the sharpness of horizontal and vertical design elements. The objective of this study was to establish the relationship between design and operating speeds for crest vertical curves with limited sight distance. Geometric data and 3,500 paired speeds (speeds at control and crest sections) were collected at 36 sites in 3 states. The results indicated that both the 85th percentile and the mean operating speeds were well above the inferred design speeds of the crest vertical curves for the range of conditions studied and that the lower the design speed the larger the difference between the 85th percentile speed and the design speed. The mean reductions in speed between the control and crest sections tend to increase as available sight distance is decreased; however, the reduction in speed is less than that suggested by current AASHTO criteria.
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Easa, Said M. "Length Requirements for New Single-Arc Unsymmetrical Vertical Curve." Transportation Research Record: Journal of the Transportation Research Board 2060, no. 1 (January 2008): 38–45. http://dx.doi.org/10.3141/2060-05.

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Traditional unsymmetrical vertical curves consist of two parabolic arcs smoothly connected at the point of common curvature. A new single-arc unsymmetrical vertical curve that takes the form of a cubic instead of parabolic function has been recently developed. The curve has a rate of change in grade that gradually varies between the start and end of the vertical curve. The single-arc curve eliminates the sudden change that exists in curvature of traditional two-arc unsymmetrical vertical curves. This paper first develops the sight distance (SD) relationships for the new single-arc curve (crest type). With these relationships, the SD profile for the new curve is established and its shape shows a substantial improvement over the abrupt-type SD profiles of the two-arc curves. The length requirements that satisfy stopping, passing, and decision SD guidelines of AASHTO are then presented. Some examples are used to illustrate the use of the developed design aids. The new single-arc curve builds on previously developed unsymmetrical vertical curves to improve curve characteristics that hopefully will promote road safety.
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Easa, Said, and Essam Dabbour. "Establishing design guidelines for compound horizontal curves on three-dimensional alignments." Canadian Journal of Civil Engineering 32, no. 4 (August 1, 2005): 615–26. http://dx.doi.org/10.1139/l05-016.

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In current design guides, the minimum radii of compound horizontal curves are based on the design requirements of simple horizontal curves for each arc on flat terrain. Such a design ignores the effects of compound curvature and vertical alignment. This paper uses computer simulation software to establish the minimum radius requirements for compound curves, considering these effects. The actual lateral acceleration experienced by a vehicle negotiating a two-dimensional (2-D) simple curve is recorded as a base scenario to facilitate the analysis of a compound curve on a flat terrain or combined with vertical alignment (three-dimensional (3-D) compound curves). The vertical alignments examined include upgrades, downgrades, crest curves, and sag curves. Mathematical models for minimum radius requirements were developed for flat and 3-D compound curves. Three types of design vehicles were used. The results show that an increase in the minimum radius ranging from 5% to 26% is required to compensate for the effects of both compound curvature and vertical alignment.Key words: highway geometric design, compound horizontal alignments, side friction, vehicle simulation, 3-D alignments.
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Dissertations / Theses on the topic "Crest vertical curves"

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Kon, Tayfun. "Collision Warning and Avoidance System for Crest Vertical Curves." Master's thesis, Virginia Tech, 1998. http://hdl.handle.net/10919/37169.

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In recent years, State Road Route 114 which is located in Montgomery County, Virginia, has gained a bad reputation because of numerous traffic accidents. Most of these accidents resulted in loss of lives and property. Although there are many suggestions and proposals designed to prevent these acidents, to date no actions is taken yet. The focus of this research is to explore a technology-based, low cost solution that will lower or eliminate the risk of accidents on this two-lane rural highway.
Master of Science
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Book chapters on the topic "Crest vertical curves"

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"1202 crest vertical curve [n] [US]." In Encyclopedic Dictionary of Landscape and Urban Planning, 202. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-540-76435-9_2769.

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"road crest [n] [UK], vertical curve of a." In Encyclopedic Dictionary of Landscape and Urban Planning, 844. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-540-76435-9_11811.

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"vertical curve [n] of a road crest [UK]." In Encyclopedic Dictionary of Landscape and Urban Planning, 1093. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-540-76435-9_15766.

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Lucarelli, Mark J. "Management of Blepharoptosis." In Surgery of the Eyelid, Lacrimal System, and Orbit. Oxford University Press, 2011. http://dx.doi.org/10.1093/oso/9780195340211.003.0014.

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A thorough understanding of upper eyelid anatomy is essential for the ptosis surgeon. The upper eyelid consists of skin, orbicularis, septum, tarsus, levator, Muller’s muscle, and conjunctiva. The skin and orbicularis form the anterior lamella. Conceptually, the orbicularis may be subdivided according to its topography into pretarsal, preseptal, and orbital components (over the orbital rim and extending to the frontalis muscle superiorly). The orbital septum is a fibrous lamellar structure arising from the periosteum over the superior and inferior orbital rims. In the upper eyelid, the orbital septum fuses with the levator aponeurosis approximately 2 to 5 mm above the superior tarsal border in Caucasians. In Asian patients, the septum extends further inferiorly into the eyelid. Preaponeurotic orbital fat is normally located behind the orbital septum in the preaponeurotic space. The preaponeurotic fat is an important landmark for surgeons as it lies immediately anterior to the levator aponeurosis. The tarsus of the upper eyelid is a firm, dense connective-tissue plate that provides rigidity to the eyelid. The upper tarsal plate measures approximately 10 mm vertically in the center of the eyelid. The tarsal plate is usually 1 mm thick. The levator complex originates from the periorbita of the lesser wing of the sphenoid at the annulus of Zinn. The muscular portion of the levator in adults is approximately 36 mm long, while the aponeurosis is 14 to 20 mm long. The bony attachments of the aponeurosis are via its horizontal expansions, the medial and lateral horns. The lateral horn, which is much stronger than the medial horn, passes through the lacrimal gland and divides it into the palpebral and orbital lobes. The lateral horn attaches to the periorbita of the orbital tubercle and to the lateral canthal tendon. The medial horn is a thin, delicate structure. It attaches loosely with the posterior portion of the medial canthal tendon and curves medially and posteriorly to insert at the posterior lacrimal crest and the adjacent periorbita of the medial orbital wall. Whitnall’s superior transverse ligament (Whitnall’s ligament) is a condensation of the fascial sheaths of the levator muscle located superior to the area of transition of the levator muscle to the levator aponeurosis (musculoaponeurotic junction).
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Conference papers on the topic "Crest vertical curves"

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Colistra, Joshua H., Mahesh V. Panchagnula, Alparslan O¨ztekin, Sudhakar Neti, and John Chen. "Interfacial Dynamics of Two Layer Couette Flow: Gravity Enhanced Kelvin-Helmholtz Instability." In ASME 2005 Fluids Engineering Division Summer Meeting. ASMEDC, 2005. http://dx.doi.org/10.1115/fedsm2005-77459.

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The Couette flow of two immiscible liquids is examined using flow visualization techniques. The flow dynamics are studied as a function of several independent parameters including gravity. The two fluids are initially separated by a sheet of aluminum sufficient in length to ensure that fully developed flow conditions are achieved for both fluids before they come in contact with each other. The experiments are performed for various flowrates of Canola Oil and Polyethylene Glycol (PEG) corresponding Reynolds numbers for Oil and PEG of 0 to 20 and 0.01 to 0.2 respectively. Photographic images of the flow field are recorded and analyzed with the aid of image analysis software to illustrate interfacial dynamics of the flow. A qualitative and quantitative analysis of the flow instability is performed for various inclinations of the test apparatus, including the extreme cases of upward vertical and downward vertical with the horizontal being the baseline test case. Neutral stability curves are identified for the range of variables studied in the experiments. The long wave instability is observed to be very periodic. At the onset of instability, the flow structure is three-dimensional and exhibits wave growth in the flow direction. The wave growth ultimately results in droplet pinch off from the crest of a folded wave. At a constant relative velocity, the wave length is at a minimum when the flow is oriented in the upward vertical direction, opposing gravity. For a given PEG flowrate, the critical Oil flowrate for the onset of interfacial instability decreases as the angle increases. These results indicate gravity enhanced Kelvin-Helmholtz interfacial instability even for low Reynolds numbers. Through a course of systematic variation of flow angles we have been able to separate the effects of inertia, gravity (buoyancy) and viscous shear forces on the wavelength of instability.
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Есин, Н., N. Esin, Н. Есин, N. Esin, О. Сорокина, and O. Sorokina. "ABOUT THE WORLD OCEAN LEVEL CHANGE IN HOLOCENE AND EVOLUTION OF THE BLACK SEA COAST AND SHELF." In Sea Coasts – Evolution ecology, economy. Academus Publishing, 2018. http://dx.doi.org/10.31519/conferencearticle_5b5ce3a02cf2a9.87992078.

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A method of calculation on local curves of the World ocean eustatic (absolute) variations is presented in this paper. It is shown that vertical motions of the Earth's Crust considerably distort eustatic curve of the sea level change (up to the contrary result). Thus, the local curves present little volume of information. A method of extraction of tectonic component from local curves is proposed. The World ocean level change in Holocene is calculated on local curves of the Mediterranean Sea. It was ascertained that the process of an active erosion of the Black Sea shelf began 3–4 ka.
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Esin, Nikolay, Nikolay Esin, Nikolay Esin, Nikolay Esin, Olga Sorokina, and Olga Sorokina. "VERTICAL MOVEMENTS OF THE COAST AND SHELF OF THE BLACK AND MEDITERRANEAN SEAS DURING THE HOLOCENE." In Managing risks to coastal regions and communities in a changing world. Academus Publishing, 2017. http://dx.doi.org/10.21610/conferencearticle_58b43158706db.

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Vertical movement of Earth crust can modify the shape of the eustatic sea level curves. A method allows calculation of the eustatic sea level course using the known local curves. We were able to divide a number of local curves of the Mediterranean Sea to the eustatic and tectonic components. The data about dynamics of the vertical crustal movements in 27 points of the Mediterranean coast and shelf during the Holocene were obtained. It was found that the velocities of raising and dipping are unstable over time and can reach value of 10 mm/year. Satellite measurements have recorded the velocities of vertical movements in the range of -10 to +20 mm/year for some parts of Black Sea coast. Such movements of the Earth's crust undoubtedly have a large impact on coastal processes and should be considered in designing coastal structures.
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Esin, Nikolay, Nikolay Esin, Nikolay Esin, Nikolay Esin, Olga Sorokina, and Olga Sorokina. "VERTICAL MOVEMENTS OF THE COAST AND SHELF OF THE BLACK AND MEDITERRANEAN SEAS DURING THE HOLOCENE." In Managing risks to coastal regions and communities in a changing world. Academus Publishing, 2017. http://dx.doi.org/10.31519/conferencearticle_5b1b9376952568.74055827.

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Vertical movement of Earth crust can modify the shape of the eustatic sea level curves. A method allows calculation of the eustatic sea level course using the known local curves. We were able to divide a number of local curves of the Mediterranean Sea to the eustatic and tectonic components. The data about dynamics of the vertical crustal movements in 27 points of the Mediterranean coast and shelf during the Holocene were obtained. It was found that the velocities of raising and dipping are unstable over time and can reach value of 10 mm/year. Satellite measurements have recorded the velocities of vertical movements in the range of -10 to +20 mm/year for some parts of Black Sea coast. Such movements of the Earth's crust undoubtedly have a large impact on coastal processes and should be considered in designing coastal structures.
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Anami, Keiko, Noriaki Ishii, Charles W. Knisely, and Tatsuya Oku. "Hydrodynamic Pressure Load on Folsom Dam Tainter-Gate at Onset of Failure Due to Flow-Induced Vibrations." In ASME 2005 Pressure Vessels and Piping Conference. ASMEDC, 2005. http://dx.doi.org/10.1115/pvp2005-71444.

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An analysis of a Folsom dam Tainter-gate which failed during operation in 1995 is presented. First, an empirical evaluation of the excessive push-and-draw hydrodynamic pressure induced by streamwise rotational vibration of the inclined circular-arc skinplate over the curved dam crest with a vertical step down at the upstream side is developed. This development is based on a theoretical analysis for a simplified flow field model. The simplified model consisted of a vertical flat rigid weir plate undergoing streamwise rotational vibration and a horizontal flat bed surface with a vertical step down at the gate position. Secondly, the resultant hydrodynamic load on the skinplate is determined. Thirdly, the dynamic instability of the Tainter-gate is theoretically examined and the major characteristics of this instability are presented. Finally, an FEM analysis of the structure reveals that the small vibration amplitude of at most 11.9mm at the spanwise center and bottom end of the skinplate induced the excessive hydrodynamic pressure load of about 1.6 times the static load, thus causing incipient failure of 4 bolts connecting a diagonal member to the main struts.
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