scholarly journals An Analysis of Unsignalised Intersection Using aaSIDRA Software

2013 ◽  
Vol 4 (2) ◽  
pp. 13-17
Author(s):  
Wan Al-Junaidi Jamil ◽  
Wan Hashim Wan Ibrahim
Keyword(s):  
Variable Parameter ◽  
Traffic Volume ◽  
Level Of Service ◽  
Highway Capacity ◽  
Peak Period ◽  
Factors Affecting ◽  
Highway Capacity Manual ◽  
Control Delay ◽  
Critical Gap ◽  
Average Control

This thesis discusses about the use of Akcelik & Associates Signalised & Unsignalised Intersection Design and Research Aid (aaSIDRA Intersection) Software in the analysis of unsignalised intersection in Sarawak, Malaysia. aaSIDRA Intersection software was used to analyse the data which were manually obtained through traffic volume study carried out at the two junctions during the morning peak period and also helps in producing the capacity and Level of Service of the intersection. Four parameters were analysed in this thesis: critical gap, follow-up time, proportion of heavy vehicles or motorcycles and total number of vehicles for each of the approaches of the intersection. Referring to the Highway Capacity Manual (HCM), these variable parameter values are determined and then the expected output of the aaSidra being used in the analysis of this study are average control delay, existing level of service, and capacity of the junction. Fixed values to be input into SIDRA Intersection are obtained from the traffic volume study. The input influences the value for the average control delay which assists in determining the Level of Service of the intersection. These output values are highly influenced by the respective input values. All factors analysed under four parameters to determine the level of service of the two junctions were contributing equally and correlates with each other and there was not one that exceeds the other factor. The critical factors affecting the level of service are critical gap and traffic volume.

scholarly journals Evaluation of Traffic Performance of Ahmed Urabi Square in Baghdad City

2018 ◽  
Vol 24 (6) ◽  
pp. 86 ◽  
Author(s):  
Esraa Thamir Al –Azawee
Keyword(s):  
Urban Areas ◽  
Traffic Volume ◽  
Geometric Design ◽  
Level Of Service ◽  
Highway Capacity ◽  
Control Delay ◽  
Traffic Performance ◽  
Traffic Volumes ◽  
Major Direction ◽  
Average Control

At present, smooth movement on the roads is a matter which is needed for each user. Many roads, especially in urban areas geometrically improved because of the number of vehicles increase from time to time. In this research, Highway capacity software, HCS, 2000, will be adopted to determine the effectiveness of roundabout in terms of capacity of roundabout, delay and level of service of roundabout. The results of the analysis indicated that the Ahmed Urabi roundabout operates under level of service F with an average control delay of 300 seconds per vehicle during the peak hours. The through movements of Alkarrada- Aljadiriya direction (Major Direction) represent the heaviest traffic volumes in Ahmed Urabi intersection. The use of underpass to serve the through movements in Alkarrada-Aljadiriya direction will lead to release the traffic volume in the Ahmed Urabi intersection with a rate 51 % .After the adoption of the proposed geometric design, it will operate at LOS B in the design year (2037). The proposed circulatory roadway width for the roundabout is 16m and the required number of lanes equal to three lanes for each side of the underpass and four lanes for all the approaches of the roundabout.  

scholarly journals Level of Service Evaluation Methods: Possible Adaptation for Lithuania

2020 ◽  
Vol 15 (2) ◽  
pp. 145-157
Author(s):  
Sandra Volosenko ◽  
Alfredas Laurinavičius
Keyword(s):  
Road Traffic ◽  
Quantitative Measure ◽  
Service Evaluation ◽  
Level Of Service ◽  
Highway Capacity ◽  
Factors Affecting ◽  
Operational Conditions ◽  
Highway Capacity Manual ◽  
The Road ◽  
Traffic Regulation

Level of Service is a quantitative measure to characterize operational conditions within a traffic stream. There is a set of factors affecting the Level of Service. These factors describe geometric parameters of the road, traffic conditions, traffic regulation conditions and base conditions. In this article, the Level of Service as a criterion for operational quality is described. Level of Service factors and performance measures are described on the basis of Highway Capacity Manual considering verifications done by countries for their own road conditions. German Highway Capacity Manual (HBS) and Highway Capacity Manual are compared for the purpose of possible adaptation for Lithuania.

Evaluation and Design of Maximum Green Time Settings for Traffic-Actuated Control

2003 ◽  
Vol 1852 (1) ◽  
pp. 246-255 ◽  
Author(s):  
Jin-Tae Kim ◽  
Kenneth G. Courage
Keyword(s):  
Design Method ◽  
Design Procedure ◽  
Time Estimation ◽  
Estimation Model ◽  
Highway Capacity ◽  
Highway Capacity Manual ◽  
Delay Minimization ◽  
Control Delay ◽  
Average Control ◽  
The One

A study is described that was conducted to develop an improved average green time estimation model for traffic-actuated control and to suggest a maximum green time design method that analytically minimizes intersection control delay. Improvements in the green time estimation model include revisions in the concept of additional queue service time, explicit treatment of right turns in lane groups containing both through and right-turning vehicles, and other improvements that include updates based on recent studies and modifications in the approaches taken for the modeling procedure. The proposed maximum green time design procedure consists of four components: ( a) estimation of the average green time of a traffic-actuated phase, ( b) performance evaluation of the system through the 2000 Highway Capacity Manual (HCM) procedure, ( c) formulation of an overall average control delay minimization problem, and ( d) a search process to find the most efficient set of maximum green time parameters that minimize the average control delay at an intersection. Using simulation as a surrogate for field data collection, it was demonstrated that the proposed average green time estimation models offer better results than the one in the 2000 HCM. In addition, it was suggested that on the basis of the improvements demonstrated in terms of design, the proposed maximum green parameter design procedure represents an advancement of the methodology for analysis of signalized intersections.

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.

scholarly journals A Novel Methodology for Estimating the Capacity and Level of Service for the New Mega Elliptical Roundabout Intersection

2020 ◽  
Vol 2020 ◽  
pp. 1-18 ◽  
Author(s):  
Ahmed I. Z. Mohamed ◽  
Yusheng Ci ◽  
Yiqiu Tan
Keyword(s):  
Geometric Design ◽  
Level Of Service ◽  
Highway Capacity ◽  
Operation Performance ◽  
Highway Capacity Manual ◽  
Federal Highway ◽  
Green Book ◽  
Traffic Operation ◽  
Gap Acceptance Theory ◽  
Better Than

Mega elliptical roundabout is a new intersection on rural multilane highways. This intersection was developed in a previous paper using simulation data, and the authors found that it is better than interchange (full cloverleaf) in most scenarios of traffic flow. Basically, there are no guidelines or procedures for designing mega elliptical roundabout in AASHTO Green Book, Federal Highway Administration guides, and Highway Capacity Manual. Thus, the purpose of this study is to analyze the traffic operation performance and propose a methodology for calculating the capacity of mega elliptical roundabout and also the level of service by gap acceptance theory. Moreover, this research studied the influence of different values of truck ratios and also different values of a major highway speed on geometric design and traffic operation performance for mega elliptical roundabout. To validate the thoroughness of the proposed methodology, VISSIM simulations were conducted. This research will assist practitioners in determining the appropriate geometric design, assessing mega elliptical roundabout intersections, and making comparisons with other alternatives.

scholarly journals Vehicle and Pedestrian Level of Service in Street Designs with Elements of Shared Space

2020 ◽  
Vol 2674 (9) ◽  
pp. 1084-1096
Author(s):  
Ioannis Kaparias ◽  
Rui Wang
Keyword(s):  
Video Data ◽  
Road User ◽  
Level Of Service ◽  
Highway Capacity ◽  
Vehicle Traffic ◽  
Highway Capacity Manual ◽  
Shared Space ◽  
Before And After ◽  
Traffic Volumes

Inspired by developments in urban planning, the concept of “shared space” has recently emerged as a way of creating a better public realm. This is achieved through a range of streetscape treatments aimed at asserting the function of streets as places by facilitating pedestrian movement and lowering vehicle traffic volumes and speeds. The characteristics of streets with elements of shared space point to the conjecture that traffic conditions and road user perceptions may be different to those on streets designed according to more conventional principles, and this is likely to have an impact on the quality of service. The aim of this paper is, therefore, to perform an analysis in relation to level of service (LOS) and to investigate how this may change as a result of the implementation of street layouts with elements of shared space. Using video data from the Exhibition Road site in London during periods before and after its conversion from a conventional dual carriageway to a layout featuring several elements of shared space, changes in relation to LOS for both vehicle traffic and pedestrians are investigated, by applying the corresponding methods from the 2010 Highway Capacity Manual. The results suggest that streets with elements of shared space provide a much improved pedestrian experience, as expressed by higher LOS ratings, but without compromising the quality of vehicle traffic flow, which, in fact, also sees slight improvements.

Validation of Left-Turn Delay at Two-Way Stop-Controlled Intersections

2000 ◽  
Vol 1710 (1) ◽  
pp. 181-188 ◽  
Author(s):  
Sarah A. Simpson ◽  
Judson S. Matthias
Keyword(s):  
Data Sets ◽  
Highway Capacity ◽  
Left Turn ◽  
Highway Capacity Manual ◽  
Control Delay ◽  
Unsignalized Intersections ◽  
Percent Confidence Level ◽  
The One ◽  
And Control ◽  
Control Delays

Control delay for left-turning vehicles at unsignalized intersections was observed in the field and compared with average control delay calculated from the methodologies presented in the 1997 update of the Highway Capacity Manual (HCM). Unsignalized intersections with two-way left-turn lanes on the major street were observed in the peak and offpeak hours, and control delays were recorded for the one-stage and twostage left-turn processes. Next, the methodologies presented in the HCM were used to calculate the control delay for both processes and compared with the observed data. These comparisons were used as the basis for validation of the HCM methodologies regarding left-turn control delay at unsignalized intersections. From the comparisons, the calculated delay closely corresponds with the observed data, with a total approach volume at the intersection of approximately 2,500 vehicles per hour or less. Once the total approach volume increases above this level, the calculated values rapidly increase and the actual observed control delays gradually increase at a much lower rate. As a result, the observed and calculated delays are different when the intersection handles more than 2,500 approach vehicles in an hour. Statistical analyses were performed on the data to determine if the average observed control delay was related to the calculated control delay. Statistically, the observed control delay and the calculated control delay at the 95 percent confidence level show that the two data sets yield similar results for off-peak conditions. However, during the peak hour, when the total approach volumes are higher, the 95 percent confidence interval yields different results. Hence, the HCM procedures produce, on average, greater control delay estimates than the field observations when the total approach volumes are high.

Unsignalized Intersection Analysis: Effect of Overlapping Conflicting Traffic Flow on Minor Movement Potential Capacity

1997 ◽  
Vol 1572 (1) ◽  
pp. 86-98
Author(s):  
Christopher J. Fasching
Keyword(s):  
Traffic Flow ◽  
Level Of Service ◽  
Traffic Flows ◽  
Highway Capacity ◽  
Highway Capacity Manual ◽  
Capacity Estimate ◽  
Potential Capacity ◽  
Count Distribution ◽  
Intersection Analysis ◽  
Poisson Count

A particular component of two-way stop unsignalized intersection analyses as presented in the 1994 Highway Capacity Manual (HCM) is described. Specifically, advantages to minor movement capacity are evaluated where traffic flows overlap in multiple lanes. From vehicular arrival data collected by the author, it was determined that the current HCM can significantly underestimate the true potential capacity of minor movements that face multiple lanes of free-flow conflicting traffic. A modification to the HCM procedure is introduced in which an “effective” conflicting flow is calculated on the basis of “blockage” caused by individual lanes of traffic, assuming a Poisson count distribution. In every case examined (24 total), a more accurate potential capacity estimate resulted relative to that determined by the HCM procedure. The modification also resulted in a more accurate level of service in 8 of the 24 cases.

Analysis and Evaluation of the Capacity of Roundabouts

1997 ◽  
Vol 1572 (1) ◽  
pp. 99-104 ◽  
Author(s):  
Abishai Polus ◽  
Sitvanit Shmueli
Keyword(s):  
The United States ◽  
Gap Acceptance ◽  
Highway Capacity ◽  
Left Turn ◽  
Highway Capacity Manual ◽  
Explanatory Variables ◽  
Geometric Characteristics ◽  
Critical Gap ◽  
Unsignalized Intersections ◽  
German Model

Roundabouts are replacing conventional unsignalized intersections in many parts of the world and could become more widespread in the United States, although there are some limitations as well as clear advantages. Models for entry capacity into the rotary were developed. Entry capacity depends on the geometric characteristics of the roundabout, particularly the diameter of the outside circle of the intersection. The geometric characteristics determine the speed of vehicles around the central island and, therefore, have an impact on the gap-acceptance process and consequently the capacity. Traffic conditions that impede entry capacity involve the flow around the roundabout. Flow and geometric data from six small to medium-sized roundabouts were analyzed. Individual and aggregated entry-capacity models were calibrated by using the diameter and circulating flows as explanatory variables. Very good fits to the data were obtained; the results also fit models developed in other countries. The Australian model resulted in slightly higher entry capacities for moderate to low circulating flows and lower entry capacities for high circulating flows. Very close proximity to the German model was obtained, although it does not depend on the geometric characteristics of the circle. The roundabout provides an advantage over a conventional unsignalized intersection. A faithful concurrence between the model developed and the latest Highway Capacity Manual model for right-turn capacity at an unsignalized intersection is obtained if the circulating flow is replaced by the conflicting flow. The advantage of entry capacities of the roundabout over the calculated capacities of the Highway Capacity Manual left-turn model is shown. Further research is proposed to study the effect on entry capacity of two circulating lanes rather than one and the effect of the increase in circulating flows on the gap-acceptance process, particularly the reduction in critical gap at high flows.

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