Evaluation of Off-ramp Right Turn Control at Single Point Urban Interchanges Without Frontage Roads PDF Download
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Author:
Publisher:
ISBN:
Category : Express highway interchanges
Languages : en
Pages : 166
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Book Description
This study focused on the control of the off-ramp right turn movement at single point urban interchanges (SPUIs) without frontage roads. The objective of this research project was to evaluate the safety and efficiency of traffic control for off-ramp right turns. For the purposes of this project, two common forms of off-ramp right turn traffic control were investigated: signal control and yield control. The process followed during this research focused on two main aspects of the off-ramp right turn movement: safety and operations. The project was composed of the following stages: literature review, safety analysis and operation analysis. Literature Review: A literature review was conducted to provide the research team a broader perspective on other studies concerned with this aspect of SPUIs. The review was looking for the various traffic controls and interchange configurations that could particularly affect the safety and operation efficiency of off-ramp right turn movement. Safety Analysis: Long-term trends in crash occurrences and short-term observations of conflicts at six study sites (12 off-ramp locations) were analyzed. Crash rates and conflict rates were determined in order to compare and contrast the two means of assessing safety as well as how they relate to the type of the traffic control used at the off-ramps. Operations Analysis: Detailed traffic data collected at the study sites were used to calculate actual delays for off-ramp right turn movements at the study sites. These field data were also used to conduct simulations of interchange sites, which supplemented the calculations based on the limited sample of study sites. The simulation models provided a means of testing different combinations of off-ramp right turn control types and overall interchange conditions in order to determine the effects of signal and yield control.
Author:
Publisher:
ISBN:
Category : Express highway interchanges
Languages : en
Pages : 166
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Book Description
This study focused on the control of the off-ramp right turn movement at single point urban interchanges (SPUIs) without frontage roads. The objective of this research project was to evaluate the safety and efficiency of traffic control for off-ramp right turns. For the purposes of this project, two common forms of off-ramp right turn traffic control were investigated: signal control and yield control. The process followed during this research focused on two main aspects of the off-ramp right turn movement: safety and operations. The project was composed of the following stages: literature review, safety analysis and operation analysis. Literature Review: A literature review was conducted to provide the research team a broader perspective on other studies concerned with this aspect of SPUIs. The review was looking for the various traffic controls and interchange configurations that could particularly affect the safety and operation efficiency of off-ramp right turn movement. Safety Analysis: Long-term trends in crash occurrences and short-term observations of conflicts at six study sites (12 off-ramp locations) were analyzed. Crash rates and conflict rates were determined in order to compare and contrast the two means of assessing safety as well as how they relate to the type of the traffic control used at the off-ramps. Operations Analysis: Detailed traffic data collected at the study sites were used to calculate actual delays for off-ramp right turn movements at the study sites. These field data were also used to conduct simulations of interchange sites, which supplemented the calculations based on the limited sample of study sites. The simulation models provided a means of testing different combinations of off-ramp right turn control types and overall interchange conditions in order to determine the effects of signal and yield control.
Author: Arizona Transportation Research Center
Publisher:
ISBN:
Category : Express highway interchanges
Languages : en
Pages : 4
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Book Description
Author: James A. Bonneson
Publisher:
ISBN:
Category : Roads
Languages : en
Pages : 76
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Book Description
Author: Carroll J. Messer
Publisher: Transportation Research Board
ISBN: 9780309048682
Category : Technology & Engineering
Languages : en
Pages : 116
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Book Description
Author: James Allen Bonneson
Publisher:
ISBN:
Category : Roads
Languages : en
Pages : 482
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Book Description
Author: American Association of State Highway and Transportation Officials
Publisher: AASHTO
ISBN: 156051325X
Category : Technology & Engineering
Languages : en
Pages : 134
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Book Description
This guide replaces the 1984 publication entitled An Informational Guide for Roadway Lighting. It has been revised and brought up to date to reflect current practices in roadway lighting. The guide provides a general overview of lighting systems from the point of view of the transportation departments and recommends minimum levels of quality. The guide incorporates the illuminance and luminance design methods, but does not include the small target visibility (STV) method.
Author: Rawan Ramadhan
Publisher:
ISBN:
Category : Roads
Languages : en
Pages : 52
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Book Description
In 1960, there were 74,431,800 vehicles registered in the United States. Looking at the most recent data currently available shows that in 2016 there were 268,799,083 registered vehicles in the United States. Roadway facilities constructed in the 1960s were not designed to handle vehicular traffic of these proportions. The ever increasing volumes of motor vehicle traffic at heavily traveled interchanges and intersections heighten the risk of single or multiple vehicle crashes particularly when they are not designed to manage high volumes. Traffic engineers from state and federal departments of transportation have responded to calls for safer roads and interchanges in some areas that have been identified as dangerous because of an increase in fatal and non-fatal motor vehicle crashes. In the road network the highway system and the local street system are related. According to the Federal Highway Administration, "the term interchange means the junction of two or more streets requiring partial or complete grade separation." Interchanges located in urban areas are utilized to facilitate traffic flow between arterial roadways and freeways on- and off-ramps. Congestion and safety are the two main objectives traffic engineers consider while remodeling an interchange design. Several types of renovated interchanges are normally considered to meet the growing population mobility needs. The Single Point Urban Interchange (SPUI) is one of the solutions has been considered since 1974 but it was flourished and implemented in the 1990s. The other innovative interchange solution appeared first in France in the mid-1970s known as Diverging Diamond Interchange (DDI). Likewise, the DDIs did not gain popularity back then until in the 2000s. The first DDI in the United States was constructed in 2009 in Springfield, Missouri.The main aim of this study is to compare the performance of traffic flow between SPUI and DDI based on existing traffic data for a peak hour retrofitting an existing Conventional Diamond Interchange (CDI). The analysis of the two interchange designs in conjunction with the existing design are used in the comparison study to identify which interchange design performs best among each other. The Measures of Effectiveness (MOEs) used in this study include queue delay, queue length, vehicle delay and stopped delay. This study obtain traffic turning movements and signal timing data from the Ohio Department of Transportation (ODOT). The turning movement counts (TMC) were taken from ODOT's Transportation Data Management System for the year 2017. VISSIM version 11 software was used for microscopic simulation. The optimum signal phasing for the three interchange designs were obtained from SYNCHRO 10 software based on the PM peak hour traffic data. The virtual interchange network design geometry in both software programs were almost identical. Several assumptions were made to stay consistent as much as possible while comparing the three designs since they have completely different geometric layouts. For example, the existing CDI data included the through movements from off-ramps to on-ramps. Since the two alternative designs (SPUI and DDI) exclude the through movements from off-ramps to on-ramps, their data were added to the right turn movements. Moreover, the speed limit was set to be in the range of 30 mph while driving in the interchange to meet all three design specifications.The analysis of results show that there are significant advantages and disadvantages associated with each design (CDI, SPUI and DDI). During implementation, various factors such as cost, efficiency, safety, delay, etc., need to be considered when attempting to select the best design, which would be the most appropriate method as these may vary from situation to situation. However, in the current study, a DDI performed best, followed by a SPUI, and then CDI was last. Moreover, CDI with its signal timing optimized very highly improved all MOEs considered when compared with the CDI with existing signal timing.
Author: Rui Yue
Publisher:
ISBN: 9780355052558
Category : Electronic books
Languages : en
Pages : 55
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Book Description
Signalized urban interchanges are frequently used as junctions between freeways and local arterials to date. In recent years, many new interchange or intersection designs like Diverging Diamond Interchange (DDI) and Continuous-flow Intersection (CFI) have emerged across the world. However, most of the interchanges are still using conventional urban interchange designs. Among new designs, Single Point Urban Interchange (SPUI) and Tight Diamond Interchange (TDI) are the most popular. Comparison and evaluation of the safety and operation of interchanges are important in transportation engineering to choose the most appropriate option for a location. Recently, many research have been devoted to the standard TDI and SPUI. Most of them consistently prove that the SPUI outperforms TDI in operation efficiency, but few research have compared the SPUI with frontage road (SPUI-F) with TDI. This research aims to fill this gap. With this motivation, there was a real case which could be used as testing the operational efficiency between the TDI and SPUI-F. The Nevada Department of Transportation (NDOT) switched the TDI, which was located at I-580/Plumb Ln, to SPUI-F in 2003. Since this interchange has experienced TDI and SPUI-F, the Measures of Effectiveness (MOEs) for each of them can be compared. To perform this comparison, layouts of both interchanges were modeled in VISSIM. The models were calibrated using the existing volume. Several volume scenario groups were designed for testing the operational efficiency of both options. Three MOEs, including average delay, average speed and average queue length, were selected to show the operational efficiency. The results revealed that the TDI is more efficient in comparison to the SPUI-F. However, TDI might not satisfy the driver’s expectation because of the stopping between the two signals, for which SPUI-F does not have such a problem.
Author:
Publisher:
ISBN:
Category : Express highways
Languages : en
Pages : 102
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Book Description
The adequate spacing and design of access to crossroads in the vicinity of freeway ramps are critical to the safety and traffic operations of both the freeway and the crossroad. The research presented in this report develops a methodology to evaluate the safety impact of different access road spacing standards. The results clearly demonstrate the shortcomings of the AASHTO standards and the benefits of enhancing them. The models developed as part of this research were used to compute the crash rate associated with alternative section spacing. The study demonstrates that the models satisfied the statistical requirements and provide reasonable crash estimates. The results demonstrate an eight-fold decrease in the crash rate when the access road spacing increases from 0 to 300 m. An increase in the minimum spacing from 90 m (300 ft) to 180 m (600 ft) results in a 50 percent reduction in the crash rate. The models were used to develop lookup tables that quantify the impact of access road spacing on the expected number of crashes per unit distance. The tables demonstrate a decrease in the crash rate as the access road spacing increases. An attempt was made to quantify the safety cost of alternative access road spacing using a weighted average crash cost. The weighted average crash cost was computed considering that 0.6, 34.8, and 64.6 percent of the crashes were fatal, injury, and property damage crashes, respectively. These proportions were generated from the field observed data. The cost of each of these crashes was provided by VDOT as $3,760,000, $48,200, and $6,500 for fatal, injury, and property damage crashes, respectively. This provided an average weighted crash cost of $43,533. This average cost was multiplied by the number of crashes per mile to compute the cost associated with different access spacing scenarios. These costs can assist policy makers in quantifying the trade-offs of different access management regulations.
Author:
Publisher: Aashto
ISBN:
Category : Express highways
Languages : en
Pages : 20
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Book Description
