scholarly journals An Improvement of Three Leg Signalized Intersections in Duhok City Kurdistan-Iraq

2018 ◽  
Vol 7 (4) ◽  
pp. 87
Author(s):  
Baran R. Omer ◽  
Sherzad W. Khalid
Keyword(s):  
Cycle Time ◽  
Signalized Intersections ◽  
Signalized Intersection ◽  
Level Of Service ◽  
Remarkable Improvement ◽  
Iraqi Kurdistan ◽  
Length Changes ◽  
Time Changes ◽  
Geometric Changes ◽  
The City

Nowadays, number of cars increases in Iraqi Kurdistan. Duhok is one of the Iraqi Kurdistan cities where an enormous increase in the number of cars and population is noticed during the last decade. Roads were been mended according to the 1970s plans where the city was small and number of cars was few. Although the city geographically is located in a hilly area and between two mountains, mending roads is a problem of area. Roads in the mentioned city are quite busy due to the high number of cars, traffic jams can be noticed in every corner of the city especially in signalized intersections. The level of service (LOS) in most of the signalized intersections is F or E. in order to lower the high (LOS), a three leg signalized intersection has been chosen to do an improvement on. During the study the number of the cars (Volume) have been enumerated in all lane groups and the results showed that the (LOS) was E in the intersection. As a result, some solutions have been provided according to the site area and the traffic flow. Solutions were geometric changes, cycle time changes or combination in both geometric and cycle time changes. According to the collected data, it was found that level of service was E for WB and SB and for EB was D. Based on data analysis it was found that LOS has not been improved when only one of the mentioned solutions is applied. In order to have the best improvement, the combination between geometric and cycle time length changes are applied. Analysis showed that there was a remarkable improvement in LOS and changed from E to D.

Before–After Evaluation of Left-Turn Lane Extension Considering Injury Severity and Collision Type

2020 ◽  
Vol 2674 (8) ◽  
pp. 67-77
Author(s):  
Yanyong Guo ◽  
Tarek Sayed
Keyword(s):  
Injury Severity ◽  
Treatment Effectiveness ◽  
Signalized Intersection ◽  
Left Turn ◽  
Remarkable Improvement ◽  
Intervention Models ◽  
Collision Type ◽  
Effectiveness Index ◽  
The City ◽  
Vehicle Deceleration

Left-turn lanes are commonly used to provide space to accommodate vehicle deceleration and provide adequate storage of turning vehicles. The objective of this study is to evaluate the safety effectiveness of extending the length of left-turn lanes at signalized intersection approaches. Five years of collision data including injury severity and collision type from three treatment sites and 31 comparison sites in the City of Surrey, Canada were used in the study. The analysis focused on target crashes including left-turn-related rear-end and left-turn-related sideswipe collisions. A full Bayesian (FB) before–after analysis was conducted for all collisions, severity levels, and collision types. Multivariate Poisson–lognormal linear intervention models were used for the analysis. The treatment effectiveness index was calculated to quantitatively measure the effectiveness of the safety treatment. The FB before–after results showed that the treatment-related collisions were reduced by 57.4% following the implementation of extended left-turn lane. The reduction in injuries and fatalities collisions (63.8%) was greater than that in property damage only collisions (55.7%). The decrease in rear-end collisions (62.8%) was greater than that in sideswipe collisions (58.1%). The findings indicate a remarkable improvement in safety after the length extension of the left-turn lane.

Analysis on Capacity and LOS of Signalized Intersection in Slight Snowy Weather

2012 ◽  
Vol 209-211 ◽  
pp. 930-933 ◽  
Author(s):  
Chun Xiao Liu ◽  
Guo Zhu Cheng ◽  
Ya Ping Zhang
Keyword(s):  
Signalized Intersections ◽  
Signalized Intersection ◽  
Level Of Service ◽  
Line Method ◽  
Sunny Weather ◽  
American Standard ◽  
Operation Status ◽  
Traffic Operation ◽  
Stop Line

In order to evaluate traffic operation status of signalized intersection in slight snowy weather, it was studied that the influence of slight snow on capacity and level of service (LOS) of signalized intersection. Data of timing, vehicle’s starting loss time, saturated headway of straight vehicle and delay of one signalized intersections in sunny and slight snowy weather were observed by video method. Stop-line method was adopted to calculate the capacity of signalized intersection and LOS was evaluated by American standard. It showed that capacity of signalized intersection decreased by 7% and LOS declined one level in slight snowy weather compared with on sunny weather.

QUANTITATIVE APPROACH TO DETERMINE PEDESTRIAN DELAY AND LEVEL OF SERVICE AT SIGNALIZED INTERSECTION

2018 ◽  
Vol 6 (1) ◽  
pp. 06-13
Author(s):  
Ammu Gopalakrishnan ◽  
Sewa Ram ◽  
Pradip Kumar Sarkar
Keyword(s):  
Empirical Model ◽  
Cycle Time ◽  
Quantitative Approach ◽  
Heterogeneous Traffic ◽  
Signalized Intersection ◽  
Level Of Service ◽  
Physical Parameters ◽  
Linear Regression Models ◽  
Traffic Conditions ◽  
Motorized Vehicles

Purpose: Level of Service is a widely adopted terminology to determine the efficiency of any transport system. From the literature it was studied that the multiple linear regression models established by many researchers to determine PLoS evolved with addition or removal of one or more physical parameters or with respect to the perception of users from different locations. At an intersection, there is little or no established methodology developed so far to determine a quantitative approach for PLoS similar to Vehicular Level of Service (VLoS). It was also pointed out that under heterogeneous traffic conditions, pedestrians are most vulnerable at intersections and they share the same space with motorized vehicles for crossing movements. Methodology: Thus, this study was built on the hypothesis that pedestrian delay of a signalized intersection is quantitatively dependent on pedestrian volume, vehicular volume and cycle time. Two signalized intersections operating as fully actuated and fixed cycle time were considered for study for period of four hours each, covering two hours of morning peak and off-peak hour traffic data. Main Findings: Using various statistical techniques, an empirical model was developed between the pedestrian delay and independent variables namely cycle time, pedestrian volume and vehicular volume. PLoS range was also determined through k-means clustering technique. Implications: The empirical model developed was validated and the application of this research was also explained. Novelty: The study is a new quantitative approach to determine PLoS and was limited to two intersections. Increase in the data may improve the accuracy of the model.

Real-Time Inductive-Signature-Based Level of Service for Signalized Intersections

2002 ◽  
Vol 1802 (1) ◽  
pp. 97-104 ◽  
Author(s):  
Cheol Oh ◽  
Stephen G. Ritchie
Keyword(s):  
Real Time ◽  
Traffic Management ◽  
Signalized Intersections ◽  
Signalized Intersection ◽  
Traffic Information ◽  
Level Of Service ◽  
Self Organizing Map ◽  
Threshold Values ◽  
Support Tool ◽  
Traffic Conditions

The Highway Capacity Manual (HCM) presents a procedure for estimating signalized intersection control delay, which is used to determine level of service (LOS) and to evaluate intersection performance. The HCM is used extensively by traffic engineers. However, it is intended as an offline decision support tool for planning and design. To meet user requirements of advanced traffic management and information systems, new LOS criteria are required for real-time intersection analysis. The objective of this research was to demonstrate a technique for development of such LOS criteria. The study used a new measure of effectiveness, called reidentification delay (RD), derived from analysis of vehicle inductive signatures and reidentification of vehicles traveling through a major signalized intersection in the city of Irvine, California. Two main issues regarding real-time LOS criteria were tackled. The first was how to determine the threshold values partitioning the LOS categories. To provide reliable real-time traffic information, the threshold values should be decided on so that RDs within the same LOS category would represent similar traffic conditions as much as possible. RDs in different LOS categories should also represent dissimilar traffic conditions. The second issue concerned the aggregation interval to use for RD in deriving LOS categories. An investigation of both fixed and cycle-based aggregation intervals was conducted. Several clustering techniques were then employed to derive LOS categories, including k-means, fuzzy, and self-organizing map approaches. The resulting real-time LOS criteria were then determined. The procedures used in this study are readily transferable to other signalized intersections for the derivation of real-time LOS.

Delay Variability at Signalized Intersections

2000 ◽  
Vol 1710 (1) ◽  
pp. 215-221 ◽  
Author(s):  
Liping Fu ◽  
Bruce Hellinga
Keyword(s):  
Analytical Model ◽  
Signalized Intersections ◽  
Signalized Intersection ◽  
Level Of Service ◽  
Cycle Times ◽  
Traffic Conditions ◽  
Cycle Simulation ◽  
Proposed Model ◽  
Delay Variability ◽  
Practical Implications

Delays that individual vehicles may experience at a signalized intersection are usually subject to large variation because of the randomness of traffic arrivals and interruption caused by traffic signal controls. Although such variation may have important implications for the planning, design, and analysis of signal controls, currently no analytical model is available to quantify it. The development of an analytical model for predicting the variance of overall delay is described. The model is constructed on the basis of the delay evolution patterns under two extreme traffic conditions: highly undersaturated and highly oversaturated conditions. A discrete cycle-by-cycle simulation model is used to generate data for calibrating and validating the proposed model. The practical implications of the model are demonstrated through its use in determining optimal cycle times with respect to delay variability and in assessing level of service according to the percentiles of overall delay.

scholarly journals Impact Assessment of Driver Distraction by Cellphone on Start-up Lost-time and Average Saturation Headway at Signalized Intersections Based on Vehicle Position in the Queue

2021 ◽  
Vol 49 (4) ◽  
pp. 359-368
Author(s):  
Nawaf Alshabibi
Keyword(s):  
Signalized Intersections ◽  
Signalized Intersection ◽  
Level Of Service ◽  
Total Delay ◽  
Main Hypothesis ◽  
Start Up ◽  
Lost Time ◽  
Vehicle Position ◽  
Secondary Hypothesis ◽  
The Impact

Cellphone usage has a significant impact on signalized intersections' capacity and level of service. This study investigated the impact of cellphone usage on signalized intersection capacity and level of service in Dammam Metropolitan Area, Saudi Arabia. The data included 183 useful cycles and 2407 start-up lost time and average saturation headway values at cycles with cellphone usage and cycles without cellphone usage at 24 signalized intersections. The main hypothesis of the study is that cellphone usage increases the start-up lost time at signalized intersection capacity. The secondary hypothesis is that cellphone usage increases the average saturation headway at signalized intersections. Normal distribution and z-test were conducted to assess whether there is a significant increase in average saturation headway and start-up lost time. The study found a significant increase in start-up lost time of about 0.7 seconds but found no significant increase in average saturation headway due to cellphone usage. Also, start-up lost time increases as vehicles of cellphone users get closer to the stop line of the signalized intersections. Thus, cellphone usage decreases the progression of 13 vehicles per hour due to a reduction in effective green time, increases total delay, and deteriorates the level of service. The study can assist transportation and traffic officials to optimize signal operation to mitigate the impact of cellphone usage and improve urban transportation.

Modeling the Level of Service of the Non-Motorized Vehicle Crossing the Signalized Intersection

CICTP 2020 ◽  
2020 ◽  
Author(s):  
Ye Yao ◽  
Xiaofei Ye ◽  
Zhen Yang ◽  
Qiming Ye ◽  
Chang Yang
Keyword(s):  
Signalized Intersection ◽  
Level Of Service

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.

scholarly journals Trajectory Planning Method for Mixed Vehicles Considering Traffic Stability and Fuel Consumption at the Signalized Intersection

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Shan Fang ◽  
Lan Yang ◽  
Tianqi Wang ◽  
Shoucai Jing
Keyword(s):  
Fuel Consumption ◽  
Trajectory Planning ◽  
Signalized Intersections ◽  
Planning Method ◽  
Signalized Intersection ◽  
Driver Model ◽  
Connected Vehicles ◽  
Connected Vehicle ◽  
Traffic Lights ◽  
Trigonometric Model

Traffic lights force vehicles to stop frequently at signalized intersections, which leads to excessive fuel consumption, higher emissions, and travel delays. To address these issues, this study develops a trajectory planning method for mixed vehicles at signalized intersections. First, we use the intelligent driver car-following model to analyze the string stability of traffic flow upstream of the intersection. Second, we propose a mixed-vehicle trajectory planning method based on a trigonometric model that considers prefixed traffic signals. The proposed method employs the proportional-integral-derivative (PID) model controller to simulate the trajectory when connected vehicles (equipped with internet access) follow the optimal advisory speed. Essentially, only connected vehicle trajectories need to be controlled because normal vehicles simply follow the connected vehicles according to the Intelligent Driver Model (IDM). The IDM model aims to minimize traffic oscillation and ensure that all vehicles pass the signalized intersection without stopping. The results of a MATLAB simulation indicate that the proposed method can reduce fuel consumption and NOx, HC, CO2, and CO concentrations by 17%, 22.8%, 17.8%, 17%, and 16.9% respectively when the connected vehicle market penetration is 50 percent.

Optimization Method of Cycle Time in Signalized Intersection

CICTP 2017 ◽  
2018 ◽  
Author(s):  
Xiaotong Ma ◽  
Hong Chen ◽  
Danting Zhao ◽  
Siyu Yang ◽  
Zhanguo Song
Keyword(s):  
Cycle Time ◽  
Optimization Method ◽  
Signalized Intersection
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