MIDBLOCK U–TURN FACILITIES ON MULTILANE DIVIDED HIGHWAYS: AN ASSESSMENT OF DRIVER’S MERGING GAP AND STOP DELAYS

2015 ◽  
Vol 76 (14) ◽  
Author(s):  
Othman Che Puan ◽  
Che Ros Ismail ◽  
Mohd Rosli Hainin ◽  
Anil Minhans ◽  
Nur Syahriza Muhamad Nor
Keyword(s):  
Road Traffic ◽  
Video Recording ◽  
Primary Objective ◽  
Major Road ◽  
Highway Capacity ◽  
Highway Capacity Manual ◽  
Critical Gap ◽  
Planning And Design ◽  
Traffic Delays ◽  
Traffic Volumes

This paper discusses the results of a study which was carried out with a primary objective to evaluate the merging gaps and traffic delays at midblock U–turn facilities installed on multilane divided highways. A total of more than 2,000 U–turn drivers at a midblock U–turn facility on an urban multilane highway were observed using a camera–video recording technique. The data pertaining to the analysis of gap acceptance and rejection was abstracted from the video–playbacks using a computer event recording program. The analysis found that the critical gap of the drivers at a midblock U–turn facility is in the range of 4.0 – 4.5 seconds, which is different from the values reported for studies carried out in other countries. The effect of major road traffic volumes on the stop delays to the U–turn drivers could not be established because the data did not exhibit any specific trend. The drivers were observed to make forced merging maneuvers when traffic volumes in the main traffic stream are relatively heavy. Such maneuvers lead to flow breakdown in the major road to occur at a faster rate. The findings suggest that there is a need for a thorough study to be carried out to evaluate the current practice of U–turn facility design and assessment methods since traffic operations at such a facility is different from those at on–ramp facilities where their planning and design are generally based on the American Highway Capacity Manual. 

Assessing Heavy Vehicle Impacts on Operation of Rural At-Grade Intersections in Brazil

1996 ◽  
Vol 1555 (1) ◽  
pp. 83-90
Author(s):  
José Reynaldo Setti ◽  
Sergio Henrique Demarchi
Keyword(s):  
Simulation Model ◽  
Road Traffic ◽  
Vehicle Classification ◽  
Heavy Vehicle ◽  
Major Road ◽  
Passenger Cars ◽  
Highway Capacity ◽  
Highway Capacity Manual ◽  
Minor Road ◽  
Time Required

A simulation model was used to assess the impacts of trucks on the capacity of rural, at-grade, stop-controlled intersections in Brazil. The major differences between Brazilian and North American vehicles and intersections are discussed and a system for vehicle classification that reflects the characteristics of Brazilian vehicles is proposed. The proposed simulation model assumes that there is an endless queue of vehicles that approaches the intersection from the minor road. Gaps in the major road traffic flow are generated using a displaced exponential distribution. Crossing times and gap acceptance are modeled by logit models fitted for each vehicle category. Heavy vehicle equivalence factors are calculated as the average number of passenger cars that are able to cross the major road during the time required by each truck type to execute the same maneuver. The capacity estimates obtained with the model are similar to values calculated with Siegloch's model, which is the basis for the Highway Capacity Manual (HCM) procedure. The equivalence factors estimated for trucks are considerably higher than those suggested in the HCM for most truck categories.

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.

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.

Minor Road Traffic Delays at Priority Junctions on Low Speed Roads in Suburban Areas

2014 ◽  
Vol 70 (4) ◽  
Author(s):  
Mohammad Ali Sahraei ◽  
Othman Che Puan ◽  
M. Al–Muz–zammil Yasin
Keyword(s):  
Time Delays ◽  
Road Traffic ◽  
Video Recording ◽  
Operational Performance ◽  
Road Vehicles ◽  
Recording Technique ◽  
Suburban Areas ◽  
Minor Road ◽  
Traffic Delays ◽  
Traffic Delay

Traffic delay is one of the important aspects considered in the assessment of the operational performance of intersections. In the analysis of priority or unsignalised junctions, delays to minor road vehicles are often estimated using the existing mathematical models. However, the applicability of such a model depends on the basis and the source of the data with which the model was calibrated. This study was carried out to evaluate traffic delays to minor road vehicles at priority junctions in suburban areas. The data were collected at two priority junctions using video recording technique. The results showed that the day time delays were longer than of those observed during the twilight time. In both situations, delay to minor road vehicles increases as the volume of major road traffic increases. However, the effect of conflicting volume on the delay to the minor road vehicles is not clear. The comparisons between observed delay and the values predicted using the HCM and Tanner’s models indicated that, in general, the observed delays are much lower than the values predicted by both models particularly during the day time. Such a finding suggests that both HCM and Tanner’s models are not directly applicable to the analysis of delays at priority junctions in Malaysia.

Saturation Flow and Capacity of Shared Lanes: Comparative Evaluation of Estimation Methods

1996 ◽  
Vol 1555 (1) ◽  
pp. 50-58
Author(s):  
G. A. Glannopoulos ◽  
Muhammad A. S. Mustafa
Keyword(s):  
Flow Rate ◽  
Comparative Evaluation ◽  
Field Measurements ◽  
Estimation Methods ◽  
Highway Capacity ◽  
Operational Conditions ◽  
Highway Capacity Manual ◽  
Traffic Volumes ◽  
Saturation Flow Rate ◽  
Saturation Flow

The operation of shared lanes, especially in the case of permitted phasing control, is still considered a complicated task and one for which many procedures and methods have been introduced. Dealt with here is the complexity when left- or right-turn movements or both are made during the unsaturated part of the opposing traffic flow. Three main methods used for estimating the shared lane's saturation flow rate and capacity values—that used in the 1985 Highway Capacity Manual (HCM) and the Australian Road Research Board (ARRB) and the Canadian methods—were analyzed and evaluated. The methodology for the comparative evaluation was based on two main approaches. In the first approach, example 1 of Chapter 9 of the HCM was used as a case study in which left through and left through right shared lanes exist in permitted phase control. In this case several computer runs were performed using the programs SIDRA and SINTRAL to estimate saturation flow and capacity values of the shared lanes opposed by different traffic volumes of the conflicting movements. Results of this approach showed that the 1985 HCM and ARRB methods are fairly close in estimating saturation flow and capacity, whereas the Canadian method gave considerably different results. Analysis showed that the sensitivity of the Canadian method to estimate saturation flow rates of the shared lane in cases of different levels of opposing traffic was an average of 10 times higher than the average of the two other methods, which were very close in their estimation of levels of opposing traffic volumes. In the second approach, field measurements of saturation flow rate values of shared lanes at different locations and operational conditions were compared with the values estimated by the three methods under the same conditions. Results, based on field observations, revealed that the Canadian method estimates of saturation flow were always lower than the measured values. At low saturation flow values, HCM estimates were slightly higher than the observed values; however, at higher saturation flow rate values. HCM estimates closely matched the observed ones. The ARRB method estimates were quite close to the observed saturation flow values under all of the different conditions considered in the field observation task.

Accounting for Nonrandom Arrivals in Estimate of Delay at Signalized Intersections

1996 ◽  
Vol 1555 (1) ◽  
pp. 9-16 ◽  
Author(s):  
Janice Daniel ◽  
Daniel B. Fambro ◽  
Nagui M. Rouphail
Keyword(s):  
Field Data ◽  
Empirical Studies ◽  
Primary Objective ◽  
Signalized Intersections ◽  
Degree Of Saturation ◽  
Delay Model ◽  
Highway Capacity ◽  
Highway Capacity Manual ◽  
Research Show

The primary objective of this research was to determine the effect of nonrandom or platoon arrivals on the estimate of delay at signalized intersections. The delay model used in the 1994 Highway Capacity Manual (HCM) accounts for nonrandom arrivals through the variable m, which can be shown to be equal to 8kI, where k describes the arrival and service distributions at the intersection and I describes the variation in arrivals due to the upstream intersection. The 1994 HCM delay model m-values are a function of the arrival type, where the arrival type describes the quality of progression at the intersection. Although an improvement to the fixed k I-value used in the 1985 delay model, the 1994 m values are based on empirical studies from limited field data and do not account for the decrease in random arrivals as the volume approaches capacity at the downstream intersection. This research provides an estimate of the variable kI for arterial conditions. An analytical equation was developed as a function of the degree of saturation, and a separate equation was developed for each signal controller type. The results from this research show that the proposed kI's provide delay estimates closer to the measured delay compared with the delay estimates using the kI-values in the 1994 HCM delay model.

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.

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.

scholarly journals Population Density and Intensity of Traffic Connection: Spatial Analysis (Overlay)

2019 ◽  
Author(s):  
Muhammad Ichsan Ali ◽  
Muhammad Raiz Abidin
Keyword(s):  
Spatial Analysis ◽  
Population Density ◽  
Road Traffic ◽  
Service Level ◽  
Primary Data ◽  
Level Of Service ◽  
Highway Capacity ◽  
Highway Capacity Manual ◽  
The Road ◽  
The World

Congestion is one of the most significant issues which recently experienced by many cities around the world especially in developing countries such as Indonesia since the world undergoes rapid economic and human development. Rappocini district, one of the districts located in Makassar city Indonesia, is currently experiencing massive construction because of this area based on the urban planning of Makassar city associated as a residential zone which may lead to the massive potential congestion. Therefore, this study tries to analyze how population density intervenes level of service of the road. Traffic survey is a method used to collect primary data in the form of classified traffic data (PCU/hour) then analyzed using the 1997 Indonesian Highway Capacity Manual (IHCM) reference and Highway Capacity Manual (HCM) 2016. Regression analysis (SPSS) and spatial (overlay) which is used later to analyze and visualize the correlation between population density and road service level. The result shows that the population density does not cause the level of congestion. However, congestion is influenced by several factors consisted of the number of populations, population density, highway capacity and the daily average of traffic. Population density value does not influence the level of service of the road because Rappocini district is the main gate to access the Makassar city from the south of Sulawesi; therefore, the congestion mostly caused by the commuter from Gowa and Takalar Regency.Citation this paper: Ali, Muhammad Ichsan., Abidin, Muhammad Raiz., "Population Density and Intensity of Traffic Connection: Spatial Analysis (Overlay)", International Journal of Science and Research (IJSR), Volume 7 Issue 12, December 2018, 546 – 552.

Development of Maximum Weaving Length Model Based on HCM 2016

2020 ◽  
pp. 036119812097366
Author(s):  
Ali Kashani ◽  
Behrooz Shirgir
Keyword(s):  
Field Data ◽  
Volume Ratio ◽  
Geometric Parameters ◽  
Highway Capacity ◽  
Highway Capacity Manual ◽  
Traffic Conditions ◽  
Traffic Volumes ◽  
Key Features ◽  
Using Data ◽  
New Variables

Weaving segments are among the most important segments in any kind of facility. One of their key features is their maximum length (Lwmax), which determines the performance of the facility as a weaving or separate merge and diverge segments. Based on an equation in the Highway Capacity Manual (HCM 2016), only two variables VR (volume ratio) and Nwl (number of weaving lanes) influence this length. However, certain cases can be found in which traffic conditions are different but Nwl and VR values are equal. In this study, three separate weaving segments in Tehran, Iran were used and their data were collected to further analyze the influence of the traffic parameters. Calibration of field data was performed using GEH values of freeways and ramps for simulation and field traffic volumes. The simulation was therefore used on the basis of different traffic and geometric parameters, and the effects of these parameters on Lwmax were carefully observed. There were 184 simulated scenarios in Aimsun using data collected from the three weaving segments in Tehran plus simulation. In these scenarios, two geometric parameters (Nwl and Lwmax) and four traffic parameters were considered variable. It was found that for Nwl = 2 the accepted regression model containing three new variables has an R2 value equal to 0.95, and for Nwl = 3 two of the three variables were used for the model produced with an R2 value equal to 0.7.

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