Models for Lane Utilization Prediction for Lane Drop Intersections

2005 ◽  
Vol 1912 (1) ◽  
pp. 47-56 ◽  
Author(s):  
Jae-Joon Lee ◽  
Nagui M. Rouphail ◽  
Joseph E. Hummer
Keyword(s):  
North Carolina ◽  
Regression Models ◽  
Signalized Intersections ◽  
Level Of Service ◽  
Highway Capacity ◽  
Utilization Factor ◽  
Highway Capacity Manual ◽  
Multiple Regression Models ◽  
Geometric Variables ◽  
Lane Utilization

Lane drops downstream of signalized intersections can be found on many urban and suburban streets and highways. Because drivers tend to avoid using the short lane because of the potential for stressful merges downstream of the signal, the short lane is typically underused. Previous research indicates that the default lane utilization factors in the Highway Capacity Manual (HCM) appear to overestimate traffic in the short lane. The purpose of this research is to develop models to predict lane utilization factors for six intersection types and to assess how low lane utilization affects the observed intersection capacity and level of service. Traffic and signal data were collected at 47 sites in North Carolina. On the basis of 15 candidate factors, multiple regression models were developed for predicting the lane utilization factor. Field-measured delays were compared with delays estimated by the HCM with the use of regression models for lane utilization. It was found that even with the new models for lane utilization, the HCM consistently overestimated delay for all types of lane drop intersections with low lane utilization: a reassessment of the effect of lane utilization on capacity may be in order. This study also found that the downstream lane length and traffic intensity positively correlate with the lane utilization factor and that some geometric variables at the approach may also influence lane utilization.

Validation of Generalized Delay Model for Vehicle-Actuated Traffic Signals

1997 ◽  
Vol 1572 (1) ◽  
pp. 105-111 ◽  
Author(s):  
Nagui M. Rouphail ◽  
Mohammad Anwar ◽  
Daniel B. Fambro ◽  
Paul Sloup ◽  
Cesar E. Perez
Keyword(s):  
North Carolina ◽  
Field Data ◽  
Traffic Signals ◽  
Signalized Intersections ◽  
Delay Model ◽  
Highway Capacity ◽  
Generalized Model ◽  
Highway Capacity Manual ◽  
Traffic Volumes ◽  
Isolated Intersection

One limitation of the Highway Capacity Manual (HCM) model for estimating delay at signalized intersections is its inadequate treatment of vehicle-actuated traffic signals. For example, the current delay model uses a single adjustment for all types of actuated control and is not sensitive to changes in actuated controller settings. The objective in this paper was to use TRAF-NETSIM and field data to evaluate a generalized delay model developed to overcome some of these deficiencies. NETSIM was used to estimate delay at an isolated intersection under actuated control, and the delay values obtained from NETSIM were then compared with those estimated by the generalized delay model. In addition, field data were collected from sites in North Carolina, and delays observed in the field were compared with those estimated by the generalized delay model. The delays estimated by the generalized model were comparable with the delays estimated by NETSIM. The data compared favorably for degrees of saturation of less than 0.8. However, at higher degrees of saturation, the generalized model produced delays that were higher than NETSIM’s. Some possible explanations for this discrepancy are discussed. The delays estimated by the generalized model were comparable with delays observed in the field. Researchers have concluded that the generalized delay model is sensitive to changes in traffic volumes and vehicle-actuated controller settings and that the generalized delay model is much improved over the current HCM model in estimating delay at vehicle-actuated traffic signals.

Utilization of Auxiliary Through Lanes at Intersections of Four-Lane, Two-Way Roadways

2000 ◽  
Vol 1737 (1) ◽  
pp. 26-33 ◽  
Author(s):  
Mohammed S. Tarawneh
Keyword(s):  
Group Delay ◽  
Signalized Intersections ◽  
Highway Capacity ◽  
Highway Capacity Manual ◽  
Level Of Use ◽  
Adjustment Factors ◽  
Limited Length ◽  
Auxiliary Lanes ◽  
Auxiliary Through Lanes ◽  
Lane Utilization

To increase the capacity of through traffic at signalized intersections, additional lanes with limited length—called auxiliary lanes—are added to the roadway at the intersection. Because of their limited length, as well as other factors, these lanes are not as fully utilized as other continuous through lanes. Research was undertaken with two objectives: ( a) to observe and identify the level of use of auxiliary through lanes added at intersections of four-lane, two-way roadways; and ( b) to study the effects of auxiliary lane length, right-turn volume, and through/right-turn lane group delay on the level of their use. Lane-use data collected during 1,050 saturated cycles at eight signalized intersections with different auxiliary lane lengths were used to accomplish research objectives. All factors investigated—auxiliary lane length, right-turn volume, and stopped-delay—were found to contribute significantly to the use of auxiliary lanes at 0.01 level. The level of each factor’s contribution, however, was dependent on the level of the other two. Lane use of nearly one to seven straight-through vehicles per cycle, depending on levels of factors investigated, was observed at the study locations. Longer auxiliary lanes, lower right-turn volumes, and excessive approach delays encouraged the use of auxiliary lanes by straight-through vehicles. The range of lane utilization adjustment factors ( fLU-factors) calculated from field data was 0.73 to 0.82, which is lower than the 1997 Highway Capacity Manual default value of 0.91 for a three-lane through/right-turn group.

Proposed Framework for Evaluating Spillback in the Highway Capacity Manual

2017 ◽  
Vol 2615 (1) ◽  
pp. 148-158
Author(s):  
Yinan Zheng ◽  
Michael Armstrong ◽  
Gustavo de Andrade ◽  
Lily Elefteriadou
Keyword(s):  
Signalized Intersection ◽  
Level Of Service ◽  
Highway Capacity ◽  
Highway Capacity Manual ◽  
Urban Streets ◽  
Facility Type ◽  
Street Intersection ◽  
Lane Utilization ◽  
New Procedures ◽  
Data Collection Effort

Procedures detailed in the Highway Capacity Manual 2010 (HCM 2010) estimate capacity and several operational measures dictating level of service for freeway facilities and surface streets. However, these methods do not consider cases in which spillback occurs from one facility type to another. The queuing effects in oversaturated conditions as they propagate upstream onto a freeway main line or a surface street intersection are not accounted for. The objective of this paper is to propose a series of modifications to enhance the HCM 2010 methods to address spillback conditions. These modifications consider lane utilization and lane blockage under spillback conditions and consist of restructuring existing equations and reference tables as well as developing new procedures. A four-regime method is proposed for evaluating spillback effects from urban streets to diverge and weaving segments. In addition, a method is proposed to account for the spillback effects from freeway on-ramps by reducing the effective green time as a proportion of the percent of time that the queue is expected to block the upstream signalized intersection. The framework developed uses assumptions that should be further explored through an extensive, nationwide data collection effort.

Evaluation of level of service at few signalized intersections using Indian Highway Capacity Manual (Indo-HCM, 2018)

2020 ◽  
Author(s):  
B. G. Savitha ◽  
R. Satyamurthy ◽  
H. S. Jagadeesh ◽  
H. S. Sathish ◽  
T. Sundararajan
Keyword(s):  
Signalized Intersections ◽  
Level Of Service ◽  
Highway Capacity ◽  
Highway Capacity Manual

Evaluation the Performance of Al-Horh Signalized Intersection Using ArcGIS (ModelBuilder)

2017 ◽  
Vol 5 (1) ◽  
pp. 132-153
Author(s):  
Salih Suliman Kshash
Keyword(s):  
Transportation Network ◽  
Heavy Traffic ◽  
Signalized Intersections ◽  
Level Of Service ◽  
Flow Conditions ◽  
Highway Capacity ◽  
Highway Capacity Manual ◽  
Video Cameras ◽  
Motorized Vehicles ◽  
Operational Capacity

        Signalized intersections are key elements in the urban transportation network where carry heavy traffic of motorized and non-motorized vehicles and pedestrians the intersection during peak periods. Intersection congestion is expressed in terms of level of service (LOS) as defined by the Highway Capacity Manual (HCM).Level of service is defined in terms of delay and ranges from LOS A (free-flow conditions) to LOS F (long delays). Delay represents an average stopped delay per vehicle fora 15-minute analysis period. The objective of this paper is to evaluate the operational capacity of intersection (AL-Horh) in AL-Kut city.AL-Horh intersection is a ground intersection with four legs. Itrepresent one of the main intersections in Al-kut city for it links the traffic coming from Al- Zafaf Street to Al- Hora and Al- Kafaat Street. The volumes of traffic get congested   in the morning and evening at this intersection.To achieve the evolution performance of  intersection 700 TVL Samsung video cameras have been used to measure traffic volume in the intersections with 3.6mm lens and total station were used to survey the intersection  whereas ArcGIS (ModelBuilder) were used for processing for the purposes traffic analysis process.The operational analysis of the existing conditions of this intersection indicates that the LOS is (F) with an intersection delay value of 175.363sec. /vehicle.

Generalized Delay Model for Signalized Intersections and Arterial Streets

1997 ◽  
Vol 1572 (1) ◽  
pp. 112-121 ◽  
Author(s):  
Daniel B. Fambro ◽  
Nagui M. Rouphail
Keyword(s):  
Performance Measure ◽  
Signalized Intersections ◽  
Level Of Service ◽  
Delay Model ◽  
Highway Capacity ◽  
Average Delay ◽  
Variable Demand ◽  
Highway Capacity Manual ◽  
Arterial Streets ◽  
Proposed Model

Average delay per vehicle is the primary measure for determining the level of service at signalized intersections. This performance measure is also a major component in the calculation of average travel speed used to determine the level of service on arterial streets. The most widely used models for estimating delay at signalized intersections are those in Chapters 9 ("Signalized Intersections") and 11 ("Urban and Suburban Arterials") of the Highway Capacity Manual. This research reviewed the literature on models for estimating delay at signalized intersections to identify limitations and formulate revised models to address those limitations. Specific problems that were addressed included the inability to account for actuated-control parameters, oversaturation and variable demand, and metering and filtering by upstream traffic signals. The research team developed a generalized delay model to address these limitations and then validated the generalized model with both field and simulation data. The proposed model is sensitive to actuated-control parameter settings, oversaturation and variable demand conditions, and filtering and metering effects of upstream signals. The proposed model is also a good predictor of delays observed in the field and estimated by microscopic traffic simulation programs for the conditions studied. The generalized delay model is recommended for inclusion in future editions of the Highway Capacity Manual.

Modeling Capacity of Through Movement at Signalized Intersection Affected by Short Left-Turn Bay under Different Signal Settings

2021 ◽  
pp. 036119812110064
Author(s):  
Zihang Wei ◽  
Yunlong Zhang ◽  
Xiaoyu Guo ◽  
Xin Zhang
Keyword(s):  
Cycle Length ◽  
Signalized Intersections ◽  
Signalized Intersection ◽  
Essential Factor ◽  
Highway Capacity ◽  
Left Turn ◽  
Highway Capacity Manual ◽  
Proposed Model ◽  
Vehicle Demand ◽  
The One

Through movement capacity is an essential factor used to reflect intersection performance, especially for signalized intersections, where a large proportion of vehicle demand is making through movements. Generally, left-turn spillback is considered a key contributor to affect through movement capacity, and blockage to the left-turn bay is known to decrease left-turn capacity. Previous studies have focused primarily on estimating the through movement capacity under a lagging protected only left-turn (lagging POLT) signal setting, as a left-turn spillback is more likely to happen under such a condition. However, previous studies contained assumptions (e.g., omit spillback), or were dedicated to one specific signal setting. Therefore, in this study, through movement capacity models based on probabilistic modeling of spillback and blockage scenarios are established under four different signal settings (i.e., leading protected only left-turn [leading POLT], lagging left-turn, protected plus permitted left-turn, and permitted plus protected left-turn). Through microscopic simulations, the proposed models are validated, and compared with existing capacity models and the one in the Highway Capacity Manual (HCM). The results of the comparisons demonstrate that the proposed models achieved significant advantages over all the other models and obtained high accuracies in all signal settings. Each proposed model for a given signal setting maintains consistent accuracy across various left-turn bay lengths. The proposed models of this study have the potential to serve as useful tools, for practicing transportation engineers, when determining the appropriate length of a left-turn bay with the consideration of spillback and blockage, and the adequate cycle length with a given bay length.

Uncertainty in Operational Analysis of Two-Lane Highways

2002 ◽  
Vol 1802 (1) ◽  
pp. 105-114 ◽  
Author(s):  
R. Tapio Luttinen
Keyword(s):  
Input Data ◽  
Travel Speed ◽  
Level Of Service ◽  
Model Parameters ◽  
Highway Capacity ◽  
Highway Capacity Manual ◽  
Operational Analysis ◽  
Percent Time ◽  
Different Types ◽  
Percent Time Spent Following

The Highway Capacity Manual (HCM) 2000 provides methods to estimate performance measures and the level of service for different types of traffic facilities. Because neither the input data nor the model parameters are totally accurate, there is an element of uncertainty in the results. An analytical method was used to estimate the uncertainty in the service measures of two-lane highways. The input data and the model parameters were considered as random variables. The propagation of error through the arithmetic operations in the HCM 2000 methodology was estimated. Finally, the uncertainty in the average travel speed and percent time spent following was analyzed, and four approaches were considered to deal with uncertainty in the level of service.

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.

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