Triple-ring phase representation scheme for exclusive median bus lane signals

2010 ◽  
Vol 37 (8) ◽  
pp. 1117-1124 ◽  
Author(s):  
Jin-Tae Kim
Keyword(s):  
Traffic Signal ◽  
Left Turn ◽  
Phase Representation ◽  
Bus Lane ◽  
Left Turns ◽  
Representation Scheme

Current traffic signal operation at intersections on exclusive median bus lane (EMBL) corridors prevents concurrent activation of non-bus through and left-turn phases due to the conflict between left turns and buses, as EMBL lies along the conflict side of a non-bus left-turn lane. This has lowered the performance of traffic signal operation on EMBL corridors. Recognizing the need for exclusive bus signals, this paper proposes a triple-ring phase representation scheme to harmonize the non-bus phases and exclusive bus phases at EMBL intersections. The proposed triple-ring phase representation scheme increases the efficiency of traffic signal operation on EMBL corridors.

scholarly journals Design of Signal Timing Plan for Urban Signalized Networks including Left Turn Prohibition

2018 ◽  
Vol 2018 ◽  
pp. 1-16 ◽  
Author(s):  
Qinrui Tang ◽  
Bernhard Friedrich
Keyword(s):  
Travel Time ◽  
Treatment Options ◽  
User Equilibrium ◽  
Signal Timing ◽  
Stochastic User Equilibrium ◽  
Left Turn ◽  
Traffic Demand ◽  
Total Travel Time ◽  
Left Turns ◽  
Demand Patterns

Urban road networks may benefit from left turn prohibition at signalized intersections regarding capacity, for particular traffic demand patterns. The objective of this paper is to propose a method for minimizing the total travel time by prohibiting left turns at intersections. With the flows obtained from the stochastic user equilibrium model, we were able to derive the stage generation, stage sequence, cycle length, and the green durations using a stage-based method which can handle the case that stages are sharing movements. The final output is a list of the prohibited left turns in the network and a new signal timing plan for every intersection. The optimal list of prohibited left turns was found using a genetic algorithm, and a combination of several algorithms was employed for the signal timing plan. The results show that left turn prohibition may lead to travel time reduction. Therefore, when designing a signal timing plan, left turn prohibition should be considered on a par with other left turn treatment options.

Resilience of Urban Street Network Configurations under Low Demands

2020 ◽  
Vol 2674 (9) ◽  
pp. 982-994
Author(s):  
Zhengyao Yu ◽  
Vikash V. Gayah
Keyword(s):  
Routing Algorithm ◽  
Shortest Paths ◽  
Left Turn ◽  
Urban Street ◽  
Traffic Conditions ◽  
Street Networks ◽  
Shortest Distance ◽  
Left Turns ◽  
The Impact ◽  
Travel Distances

Urban street networks are subject to a variety of random disruptions. The impact of movement restrictions (e.g., one-way or left-turn restrictions) on the ability of a network to overcome these disruptions—that is, its resilience—has not been thoroughly studied. To address this gap, this paper investigates the resilience of one-way and two-way square grid street networks with and without left turns under light traffic conditions. Networks are studied using a simplified routing algorithm that can be examined analytically and a microsimulation that describes detailed vehicle dynamics. In the simplified method, routing choices are enumerated for all possible origin–destination (OD) combinations to identify how the removal of a link affects operations, both when knowledge of the disruption is and is not available at the vehicle’s origin. Disruptions on two-way networks that allow left turns tend to have little impact on travel distances because of the availability of multiple shortest paths between OD pairs and the flexibility in route modification. Two-way networks that restrict left turns at intersections only have a single shortest-distance path between any OD pair and thus experience larger increases in travel distance, even when the disruption is known ahead of time. One-way networks sometimes have multiple shortest-distance routes and thus travel distances increase less than two-way network without left turns when links are disrupted. These results reveal a clear tradeoff between improved efficiency and reduced resilience for networks that have movement restrictions, and can be used as a basis to study network resilience under more congested scenarios and in more realistic network structures.

A Laboratory Investigation of Signal Indications for Protected Left Turns

1974 ◽  
Vol 16 (1) ◽  
pp. 37-45 ◽  
Author(s):  
Ralph W. Plummer ◽  
L. Ellis King
Keyword(s):  
Motion Picture ◽  
Reaction Times ◽  
Major Objective ◽  
Motion Picture Film ◽  
Male And Female ◽  
Left Turn ◽  
Turn Signal ◽  
Different Types ◽  
The Subject ◽  
Left Turns

The major objective of this research was to investigate and compare driver comprehension and understanding of different types of left-turn signal clearance indications for protected left turns. Forty subjects, male and female drivers, were tested. The test utilized color slides and color motion-picture film segments to present the subject with both steady and flashing left-turn signal indications. After each presentation of a signal indication, the subject responded by pressing one of three answer buttons. Accuracy and reaction times of each response were recorded. The results of this investigation recommended that three signal sequences be field tested as they conveyed their intended messages to the subjects more efficiently than the remaining eleven. The results also indicated that none of the three flashing signals tested proved to be effective.

Developing Signal Warrants for Restricted Crossing U-Turn Intersections

2021 ◽  
pp. 036119812110469
Author(s):  
Justice Appiah
Keyword(s):  
Traffic Control ◽  
Simulation Analysis ◽  
Traffic Signals ◽  
Traffic Volume ◽  
Traffic Signal ◽  
Signal Control ◽  
Traffic Signal Control ◽  
Left Turn ◽  
Minor Road ◽  
Intersection Configuration

The restricted crossing U-turn (RCUT) intersection is a form of innovative intersection design that reroutes left-turn and through traffic from the minor road to U-turn crossovers on the major road. When implemented correctly, an RCUT intersection can provide significant safety and operational benefits over the conventional intersection configuration. The RCUT may be controlled by traffic signals, STOP control, merges and diverges, or a combination of these. There is currently no concrete guidance in relation to when the use of traffic signal control is warranted at an RCUT intersection. This study investigated traffic volume conditions that may warrant consideration of traffic signal control at an RCUT intersection. Simulation experiments including two geometric configurations and three traffic control schemes were designed and run in VISSIM to evaluate the effects of traffic conditions on intersection delay and queue lengths. Traffic was varied by changing the composition, approach volumes, and origin–destination flow patterns to reflect different conditions that may occur at the intersection on any given day. For the range of conditions studied, the results of the simulation analysis suggested that the RCUT intersection may operate better with traffic signals (at all junctions) when the minor roadway traffic volume is more than 450 vehicles per hour (vph) and the major roadway has two through lanes. The corresponding minor roadway volume threshold increases to 575 vph when the major roadway has four through lanes.

Risk to Bicyclists in a Separated Path from Left Turns across Multiple Lanes: A Case for Protected-Only Left Turns

2021 ◽  
pp. 036119812110107
Author(s):  
Ray Saeidi Razavi ◽  
Peter G. Furth
Keyword(s):  
Opposite Direction ◽  
Signalized Intersections ◽  
Left Turn ◽  
The Road ◽  
Turn On ◽  
Road Users ◽  
Green Ball ◽  
Left Turns ◽  
The Right

At signalized intersections, permitted left turns (i.e., on a green ball, after yielding) across multiple through lanes and across a separated bike lane or bike path present a threat to bicyclist safety. A conflict study of two such intersections with a bidirectional bike path found that when cyclists cross while a vehicle is ready to turn left and there is no opposing through traffic to block it, the chance of the left-turning motorist yielding safely was only 9%, and the chance of their yielding at all—including yielding only after beginning the turn, then stopping in the opposing through lanes—was still only 37%. Motorist non-yielding rates were worse toward bikes arriving during green, toward bikes approaching from the opposite direction (i.e., riding on the right side of the road), and toward bikes facing a queue with multiple left turning vehicles. Of 112 cyclists who arrived on green when there was at least one left-turning car, but no opposing through traffic blocking it, 73 had to slow or stop to avoid a collision. Although these conflicts could be essentially eliminated using protected-only left turn phasing (turn on green arrow), common existing criteria prefer permitted left turns to reduce vehicular delay. A case study shows how, by considering multiple signalization alternatives, it can be possible to convert left turns to protected-only phasing without imposing a substantial delay burden on vehicles or other road users.

Lane-based signal optimization with left turn prohibition in urban road networks

2019 ◽  
Vol 46 (2) ◽  
pp. 73-80
Author(s):  
Qinrui Tang ◽  
Huijun Liu ◽  
Bernhard Friedrich
Keyword(s):  
Travel Time ◽  
Road Networks ◽  
Congestion Management ◽  
Signal Timing ◽  
Left Turn ◽  
Urban Road ◽  
Total Travel Time ◽  
Left Turns ◽  
Link Travel Time ◽  
Lane Based

Left turns may generate efficiency problems, which can be solved by appropriately prohibiting left turns. The goal of this paper is to propose a method for purpose of minimizing total travel times in urban road networks by prohibiting left turns. With left turn prohibition, the signal timing plan is optimized with the lane-based method because the method can adequately handle both signal timing optimization and lane assignment. The total travel time is calculated with link flows and link travel time being estimated with signal settings. As illustrated by numerical examples, prohibiting left turns reduces the total travel time of car traffic in road networks. As the left turn prohibition results can handle the randomness in the network, these results provide potential implications for congestion management.

Assistive System to Improve Pedestrians’ Safety and Mobility in a Connected Vehicle Technology Environment

2018 ◽  
Vol 2672 (19) ◽  
pp. 145-156 ◽  
Author(s):  
Sara Khosravi ◽  
Byungho Beak ◽  
K. Larry Head ◽  
Faisal Saleem
Keyword(s):  
Traffic Signal ◽  
Connected Vehicle ◽  
Left Turn ◽  
Road Users ◽  
Connected Vehicle Technology ◽  
Roadside Unit ◽  
Vulnerable Road Users ◽  
Vehicle To Infrastructure ◽  
Communication Pathway ◽  
Near Future

Conflicts between vehicles and vulnerable road users (VRUs) often result in injuries and fatalities. This paper presents a vehicle-to-infrastructure and Wi-Fi based pedestrian conflict avoidance system to improve VRUs’ safety. Compared with the vision based systems, the proposed system can improve VRUs’ safety in non-line-of-sight situations. In particular, it can be helpful in a situation when drivers are making a right or left turn where there is a crosswalk and visibility conditions are poor. The system, called Smart Walk Assistant (SWA), was implemented as an application on a smartphone and server on a roadside unit. It includes two wireless communication pathways: pedestrian-to-infrastructure (P2I) and pedestrian-to-vehicle (P2V). The first communication pathway enables users to send a pedestrian signal request to the traffic signal controller and receive traffic signal status. The second communication pathway enables pedestrians and vehicles to exchange information including location, speed, and heading that can be used to provide conflict alerts. The SWA system may be especially beneficial to differently abled pedestrians, including blind or visually impaired pedestrians, who would benefit from active support to safely cross streets at signalized intersections. The P2I application was designed, developed, and field demonstrated. The P2V application was designed and developed, and will be field tested in the near future.

scholarly journals Statistical Analysis of Safety Performance of Displaced Left-Turn Intersections: Case Studies in San Marcos, Texas

2020 ◽  
Vol 17 (18) ◽  
pp. 6446
Author(s):  
Wenrui Qu ◽  
Qiao Sun ◽  
Qun Zhao ◽  
Tao Tao ◽  
Yi Qi
Keyword(s):  
Statistical Analysis ◽  
Traffic Signal ◽  
Safety Performance ◽  
Access Management ◽  
Left Turn ◽  
Crash Data ◽  
Safety Issues ◽  
The Road ◽  
San Marcos ◽  
Driver Acceptance

Displaced left-turn (DLT) intersections are designed to increase the mobility of vehicles by relocating the left-turn lane (lanes) to the far-left side of the road upstream of the main signalized intersection. Since DLT is a relatively new design and very limited crash data are available, previous studies have focused mainly on the analysis of its operational performance rather than its safety performance. To fill this gap, in this study, we investigated the safety performance of two DLT intersections located in San Marcos, Texas. Crash data from 2011 to April 2018 were extracted from the TxDOT Crash Record Information System (CRIS). These crash data were analyzed using two different approaches, i.e., statistical analysis and collision diagram-based analysis. The results of this study indicated that DLT did not increase the overall crash frequencies at the studied intersections. Traffic crashes related to left turns and right turns were reduced significantly by DLT. Meanwhile, it also caused safety issues related to traffic signage, traffic signal, geometric design, and access management at DLT intersections. Thus, in the implementation of DLT intersections, traffic engineers need to carefully consider different aspects of the DLT intersection design, including access management, traffic signal coordination, and driver acceptance. As a result of these analyses, recommendations were provided for the safe implementation of the DLT design in the future.

Effect of Offset between Opposing Left-Turn Lanes on Driver Performance

1996 ◽  
Vol 1523 (1) ◽  
pp. 61-72 ◽  
Author(s):  
Mohammed S. Tarawneh ◽  
Patrick T. Mccoy
Keyword(s):  
Age Groups ◽  
Older Drivers ◽  
Age And Gender ◽  
Left Turn ◽  
Sight Distance ◽  
Driver Performance ◽  
Driving Conditions ◽  
Left Turns ◽  
And Gender

The objective of the research described here was to study the effects of the offset between opposing left-turn lanes on the turning performance of drivers with respect to driver age and gender. Left-turn performance of 100 subjects within three age groups (25–45, 65–74, and 75+ years old) was evaluated under normal driving conditions at four intersections of different left-turn offset configurations. The results indicate that driver performance can be adversely affected by offsets that are much less (i.e., more negative) than the negative 0.9-m offset. Such large negative offsets significantly increase the size of the critical gaps of drivers turning left and also seem to increase the likelihood of conflicts between left turns and opposing through traffic. Large negative offsets may be particularly troublesome for older drivers and women drivers, who are less likely to position their vehicles within the intersection to see beyond vehicles in the opposing left-turn lane. Surprisingly, driver perceptions of the level of comfort and degree of difficulty were not found to improve with the increased sight distance provided by larger (i.e., more positive) offsets. The 1.8-m positive offset was associated with a lower level of comfort and a higher degree of difficulty perceived by drivers making left turns than the 0.9-m negative offset, which provided less sight distance. This may have been because the 0.9-m negative offset is much more common than the 1.8-m positive offset.

Sign in / Sign up

Export Citation Format

Share Document