Operational Effects of the Consolidated Intersection Design on Urban and Suburban Arterials

2018 ◽  
Vol 2672 (17) ◽  
pp. 96-107
Author(s):  
Daniel J. Cook
Keyword(s):  
Travel Time ◽  
Signalized Intersections ◽  
Signal Timing ◽  
Left Turn ◽  
Vehicle Delay ◽  
Cycle Lengths ◽  
Expected Benefits ◽  
Traffic Signal Timing ◽  
Critical Phases ◽  
Pedestrian Crossing

Along urban and suburban arterials, closely-spaced signalized intersections are commonly used to provide access to adjacent commercial developments. Often, these signalized intersections are designed to provide full access to developments on both sides of the arterial and permit through, left-turn, and right-turn movements from every intersection approach. Traffic signal timing is optimized to reduce vehicle delay or provide progression to vehicles on the arterial, or both. However, meeting both of these criteria can be cumbersome, if not impossible, under high-demand situations. This research proposes a new design that consolidates common movements at three consecutive signalized intersections into strategic fixed locations along the arterial. The consolidation of common movements allows the intersections to cycle between only two critical phases, which, in turn, promotes shorter cycle lengths, lower delay, and better progression. This research tested the consolidated intersection concept by modeling a real-world site in microsimulation software and obtaining values for delay and travel time for multiple vehicle paths along the corridor and adjacent commercial developments in both existing and proposed conditions. With the exception of unsignalized right turns at the periphery of the study area, all non-displaced routes showed a reduction in travel time and delay. Additional research is needed to understand how additional travel through the commercial developments adjacent to the arterial may effect travel time and delay. Other expected benefits of the proposed design include a major reduction in conflict points, shorter pedestrian crossing and wait times, and the opportunity to provide pedestrian refuge areas in the median.

Impact of Turning Lane Storage Length and Turning Proportions on Throughput at Oversaturated Signalized Intersections

2021 ◽  
pp. 036119812110171
Author(s):  
A. M. Tahsin Emtenan ◽  
Christopher M. Day
Keyword(s):  
Flow Rate ◽  
Cycle Length ◽  
Signal Timing ◽  
Real World Data ◽  
Left Turn ◽  
Common Response ◽  
Cycle Lengths ◽  
Saturation Flow Rate ◽  
Saturation Flow ◽  
Timing Strategies

During oversaturated conditions, common objectives of signal timing are to maximize vehicle throughput and manage queues. A common response to increases in vehicle volumes is to increase the cycle length. Because the clearance intervals are displayed less frequently with longer cycle lengths and fewer cycles, more of the total time is used for green indications, which implies that the signal timing is more efficient. However, previous studies have shown that throughput reaches a peak at a moderate cycle length and extending the cycle length beyond this actually decreases the total throughput. Part of the reason for this is that spillback caused by the turning traffic may cause starvation of the through lanes resulting in a reduction of the saturation flow rate within each lane. Gaps created by the turning traffic after a lane change may also reduce the saturation flow rate. There is a relationship between the proportions of turning traffic, the storage length of turning lanes, and the total throughput that can be achieved on an approach for a given cycle length and green time. This study seeks to explore this relationship to yield better signal timing strategies for oversaturated operations. A microsimulation model of an oversaturated left-turn movement with varying storage lengths and turning proportions is used to determine these relationships and establish a mathematical model of throughput as a function of the duration of green, storage length, and turning proportion. The model outcomes are compared against real-world data.

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.

Comparison of Planning and Operational Analysis Procedures for Signalized Intersections from the Highway Capacity Manual

1996 ◽  
Vol 1555 (1) ◽  
pp. 59-64
Author(s):  
Mark R. Virkler ◽  
Shashi Gannavaram ◽  
Anand Ramabhadran
Keyword(s):  
Level Of Service ◽  
Signal Timing ◽  
Highway Capacity ◽  
Operational Procedure ◽  
Highway Capacity Manual ◽  
Operational Analysis ◽  
Planning Procedure ◽  
Adjustment Factors ◽  
Cycle Lengths ◽  
Traffic Signal Timing

The 1994 update of the Highway Capacity Manual (HCM) includes a planning procedure to estimate the capacity condition of a signalized intersection (Xcm). The planning method results can also be extended to a planning application of the more data-intensive HCM operational procedure to estimate intersection critical flow-to-capacity ratio (Xc) and level of service with only planning-level data. Both the planning procedure and the planning application of the operational procedure involve default adjustment factors and synthesized traffic signal timing (called the “default signal timing”). Data from 166 Missouri intersections were used to determine how well the planning approaches predict operational analysis results. In general, the default signal timings had shorter cycle lengths than the timing plans used at pretimed signals. The shorter cycle lengths led to slightly higher flow-to-capacity ratios, since a higher proportion of each cycle was devoted to lost time. The default signal timings also had more equal flow-to-capacity ratios within critical lane groups. The shorter cycle lengths and more equal flow-to-capacity ratios led to a predicted level of service that was the same or better than that calculated for actual conditions. For the subject intersections, locally calibrated default adjustment factors yielded better predictions of flow-to-capacity ratios and level of service than the HCM defaults. The planning value for Xcm was often less than the actual Xc for operational analysis of actual conditions. This was to be expected since Xcm is based on the maximum allowable cycle length. The HCM planning procedure is expected to receive wide use in a variety of planning and design applications. Calibration of appropriate local default values should improve the accuracy of the planning procedure results.

Scramble and Crosswalk Signal Timing

1998 ◽  
Vol 1636 (1) ◽  
pp. 83-87 ◽  
Author(s):  
Mark R. Virkler
Keyword(s):  
Field Study ◽  
High Volume ◽  
Signalized Intersections ◽  
Signal Timing ◽  
Pedestrian Flow ◽  
Crossing Time ◽  
Time Required ◽  
Pedestrian Crossing

A variety of methods have been developed for determining appropriate pedestrian crossing times at signalized intersections. Although many of these methods have useful applications, all have significant shortcomings when estimating the crossing time required under high-volume conditions and with two-way flow within a crosswalk. Existing methods are described. A field study conducted to address these shortcomings is then described. The results of the study are used to develop relationships to describe pedestrian flow at signalized crossings. Recommendations are then made to improve the signal timing parameters used for higher-volume pedestrian flows.

Safety-Based Left-Turn Phasing Decisions for Signalized Intersections

2017 ◽  
Vol 2619 (1) ◽  
pp. 13-19 ◽  
Author(s):  
Kiriakos Amiridis ◽  
Nikiforos Stamatiadis ◽  
Adam Kirk
Keyword(s):  
Urban Areas ◽  
Primary Objective ◽  
Signalized Intersections ◽  
Safety Performance ◽  
Signal Timing ◽  
Left Turn ◽  
Crash Data ◽  
Intersection Safety ◽  
Traffic Volumes

The efficient and safe movement of traffic at signalized intersections is the primary objective of any signal-phasing and signal-timing plan. Accommodation of left turns is more critical because of the higher need for balancing operations and safety. The objective of this study was to develop models to estimate the safety effects of the use of left-turn phasing schemes. The models were based on data from 200 intersections in urban areas in Kentucky. For each intersection, approaches with a left-turn lane were isolated and considered with their opposing through approach to examine the left-turn–related crashes. This combination of movements was considered to be one of the most dangerous in intersection safety. Hourly traffic volumes and crash data were used in the modeling approach, along with the geometry of the intersection. The models allowed for the determination of the most effective type of left-turn signalization that was based on the specific characteristics of an intersection approach. The accompanying nomographs provide an improvement over existing methods and warrants and allow for a systematic and quick evaluation of the left-turn phase to be selected. The models used the most common variables that were already known during the design phase, and they could be used to determine whether a permitted or protected-only phase would suit the intersection when safety performance was considered.

Intersection Operation with Non-Traditional Dynamic Lane Scheme through Vehicle-to-Signal Connection

2019 ◽  
Vol 2673 (8) ◽  
pp. 322-332
Author(s):  
Sida Luo ◽  
Yu (Marco) Nie ◽  
Lin Zhu
Keyword(s):  
Integer Program ◽  
Signalized Intersections ◽  
Mixed Integer ◽  
Mixed Integer Program ◽  
Time Signal ◽  
Signal Timing ◽  
Left Turn ◽  
Intersection Operation ◽  
Lane Utilization ◽  
Near Future

This paper proposes an information-based dynamic lane (IDYL) scheme for signalized intersections with exclusive left-turn phases. Similar to the tandem design, the proposed scheme aims to increase the capacity of an isolated intersection by sorting incoming vehicles based on their turning movements. Its novelty is to guide vehicles of different movements into pre-designated dynamic lanes without stopping them via pre-signal. The assumption is that vehicles themselves or their drivers have access to, and can act on, real-time signal timing information through vehicle-to-signal connection to select the correct lane to enter as they approach the intersection. A mixed integer program is proposed to optimize jointly the lane configuration, timing plan, and dynamic lane utilization for an intersection. Results from numerical and simulation experiments show that IDYL can increase the reserve capacity by more than 25% when implemented on all legs of a standard four-leg intersection, and reduce the delay by around 15% when implemented on two opposing legs. The results from this study could help traffic engineers to operate signalized intersections with dynamic lanes when vehicle-to-signal connection becomes widely available in the near future.

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.

scholarly journals Travel Time Reliability-Based Signal Timing Optimization for Urban Road Traffic Network Control

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Zhengfeng Ma ◽  
Darong Huang ◽  
Changguang Li ◽  
Jianhua Guo
Keyword(s):  
Travel Time ◽  
Optimization Model ◽  
Road Traffic ◽  
Signal Timing ◽  
Traffic Network ◽  
Travel Time Reliability ◽  
Timing Optimization ◽  
The Road ◽  
Signal Timing Optimization ◽  
Traffic Signal Timing

Due to increasing traffic demand, many metropolitan areas are experiencing extensive traffic congestion, which demands for efficient traffic signal timing and optimization. However, conventional efficiency measure-based signal optimization cannot handle the ubiquitous uncertainty in the road networks, demanding for the incorporation of reliability measures into signal optimization, which is still in its early stage. Therefore, targeting this issue, based on the recent studies on recognizing travel time reliability (TRR) as an important reliability measure of road networks, a travel time reliability-based urban road traffic network signal timing optimization model is proposed in this paper, with the objective function to optimize a TTR measure, i.e., buffer time index. The proposed optimization model is solved using the heuristic particle swarm optimization approach. A case study is conducted using microscopic traffic simulation for a road network in the City of Nanjing, China. Results demonstrate that the proposed optimization model can improve travel time reliability of the road traffic network and the efficiency of the road traffic network as well. Future studies are recommended to expand the integration of travel time reliability into traffic signal timing optimization.

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