Review of Percent Time Spent Following (PTSF) as Performance Measure for Two-lane Highways

2013 ◽  
Vol 64 (1) ◽  
Author(s):  
Muttaka Na'iya Ibrahim ◽  
Othman Che Puan ◽  
Mushairry Mustaffar
Keyword(s):  
Empirical Studies ◽  
Measurement Model ◽  
Performance Measure ◽  
Highway Capacity ◽  
Highway Capacity Manual ◽  
Percent Time ◽  
Surrogate Measure ◽  
Analytical Procedures ◽  
Percent Time Spent Following ◽  
Related Measure

The Highway Capacity Manual (HCM) uses Percent Time Spent Following (PTSF) as key service measure for assessing the level of service of two-lane highways. However, the indicator is difficult to measure directly in the field. For this reason, its estimation to date has been based on analytical procedures using equations derived from simulations and field observations at representative location based on surrogate measure; as the percent of vehicles traveling with headway less than 3 seconds (3 s). Findings from empirical studies confirmed that the HCM analytical procedures used in estimating PTSF yield results that are inconsistent with the 3 s surrogate measure and mostly overestimate the indicator. This paper presents a review on the estimation of PTSF on two-lane highways and suggests probable approach to substantiate the application of the current practice. Further, the authors of this paper argued that the use of 3 s as surrogate for estimating PTSF based on field observation at a specific point may not represent the actual time spent following over a long segment of two-lane highway since PTSF is space related measure. Hence, the authors suggest the use of test vehicle approach over the highway segment to be evaluated to identify the variables that are required for the development of a representative PTSF measurement model. It is expected that this review and suggestion offered will contribute in advancing performance analysis of two-lane highways. 

Evaluating new methodologies for estimating performance on two-lane highways

2008 ◽  
Vol 35 (8) ◽  
pp. 777-785 ◽  
Author(s):  
Ahmed Al-Kaisy ◽  
Casey Durbin
Keyword(s):  
National Research Council ◽  
Highway Capacity ◽  
Highway Capacity Manual ◽  
Percent Time ◽  
Moving Vehicles ◽  
Study Results ◽  
New Methodologies ◽  
Analytical Procedures ◽  
Percent Time Spent Following ◽  
Study Sites

This paper examines two new methodologies for field estimation of percent time spent following (PTSF) on two-lane highways. Using speed and time headway data, the two methodologies estimate the percentage of vehicles trapped in platoons, unable to pass slow-moving vehicles. A total of 236 h of field data, including individual speeds and headways, were collected at three study sites in the state of Montana. The study examined the sensitivity of PTSF estimates to some important platooning variables. The study also included a comparison of PTSF estimates from the new methods versus those found using the current United States National Research Council Highway capacity manual (HCM) analytical procedures. Study results showed that the two new methodologies were successful in capturing the effect of platooning variables on PTSF estimates and outperformed the HCM procedures in this regard. Further, the results strongly attest to the promise of the proposed methods in advancing the current analytical procedures for estimating performance on two-lane highways.

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.

Field Evaluation of Highway Capacity Manual 2000 Analysis Procedures for Two-Lane Highways

2002 ◽  
Vol 1802 (1) ◽  
pp. 125-132 ◽  
Author(s):  
Michael P. Dixon ◽  
Satya Sai Kumar Sarepali ◽  
Kevin Allen Young
Keyword(s):  
Simulation Model ◽  
Field Data ◽  
Field Evaluation ◽  
Analysis Procedure ◽  
Highway Capacity ◽  
Highway Capacity Manual ◽  
Percent Time ◽  
Percent Time Spent Following ◽  
Northern Idaho ◽  
Rural Highway

Highway Capacity Manual (HCM) 2000 two-lane rural highway directional, two-way, and passing-lane analysis procedures based on field data and simulation were evaluated. Detailed field data were collected from two highway sections in northern Idaho, one with and one without passing lanes. The TWOPAS simulation model was used to provide additional insights. Particular attention was given to the differences in estimates for percent time spent following (PTSF) produced by the twoway and directional analysis procedures. It was found that the two-way analysis procedure was more accurate, although both procedures produced estimates that were too high. The passing-lane analysis procedure was also evaluated, and the HCM 2000 procedure was found to be conservative in its estimates of PTSF reductions due to a passing lane.

scholarly journals ESTIMACIÓN DEL NIVEL DE SERVICIO DE UN CARRIL LENTO

2016 ◽  
Author(s):  
Víctor Gabriel Valencia Alaix ◽  
Alfredo García García
Keyword(s):  
Travel Speed ◽  
Highway Safety ◽  
Design Model ◽  
Highway Capacity ◽  
Highway Capacity Manual ◽  
Percent Time ◽  
Safety Design ◽  
Percent Time Spent Following

La operación vehicular en una carretera convencional depende de la atención adecuada de los adelantamientos de los vehículos lentos por parte de los más rápidos; una alternativa es mediante la provisión de carriles auxiliares a lo largo de la vía antes de pasar a una carretera multicarril.El objetivo es calibrar el modelo de simulación TWOPAS y aplicarlo en una carretera convencional española para estimar y comparar el nivel de servicio estimado en ella y en un carril lento con el resultado del procedimiento del Highway Capacity Manual - HCM.Se observó la operación vehicular en una carretera convencional de España mediante el registro a través de cámaras de control dispuestas a lo largo de la carretera, y en el carril lento, de manera que sirvió para calibrar el modelo de microsimulación TWOPAS considerando parámetros operacionales del parque automotor y aplicándolo para estimar el nivel de servicio.Se aplicó el procedimiento del HCM para estimar el nivel de servicio en segmentos de carretera con carril lento para comparar sus resultados con los obtenidos en la simulación.El modelo de simulación usado fue el TWOPAS, inserto en el Traffic Analisys Module (TAM) del Interactive Highway Safety Design Model (IHSDM), cuyos resultados en términos de Percent Time Spent Following (PTSF), Average Travel Speed (ATS) y otros permite la evaluación operacional.Los resultados y conclusiones permiten valorar la utilidad del modelo, la correspondencia de la realidad operacional en carretera y la norma española y la conveniencia operacional del carril lento estudiado.DOI: http://dx.doi.org/10.4995/CIT2016.2016.4220

scholarly journals Operational Considerations of Passing Zones for Two-lane Highways: Spanish Case Study

2018 ◽  
Vol 30 (5) ◽  
pp. 601-612
Author(s):  
Ana Tsui Moreno ◽  
Carlos Llorca ◽  
Scott S. Washburn ◽  
Jose Elievam Jr. Bessa ◽  
Alfredo Garcia
Keyword(s):  
Road Segment ◽  
Highway Capacity ◽  
Zone Length ◽  
Highway Capacity Manual ◽  
The Road ◽  
Percent Time ◽  
Analysis Methodology ◽  
Percent Time Spent Following ◽  
Traffic Operation

The U.S. Highway Capacity Manual (HCM 2010) methodology is used in Spain to evaluate traffic operation and quality of service. In two-lane undivided highways, the effect of limiting where drivers could pass slower vehicles, or passing restrictions, is considered through the percentage of no-passing zones. This measure does not account for how passing opportunities are distributed along the road. The objective of this research was to evaluate the effect percentage of no-passing zones and average passing zone length on a two-lane highway and, if significant, incorporate them in the analysis methodology,. The TWOPAS microsimulation program was calibrated and validated to the Spanish conditions. Passing restrictions had little effect on average traffic speed (ATS), with differences lower than 6 km/h between a road segment with no passing restrictions and a road segment with a passing restriction on 100% of its length. Conversely, passing restrictions can increase the percent time spent following (PTSF) up to 30%. Increasing the passing zone length beyond 2,000 m does not improve PTSF. The new models could be used to better estimate traffic operation on Spanish two-lane highways.

Estimation of Percentage of Delayed Vehicles Based on Traffic Variables for Rural Highways

1998 ◽  
Vol 1646 (1) ◽  
pp. 29-36 ◽  
Author(s):  
Manuel G. Romana ◽  
Gemma Lépez
Keyword(s):  
Time Delay ◽  
Level Of Service ◽  
Heavy Vehicles ◽  
Highway Capacity ◽  
Sloping Ground ◽  
Rural Highways ◽  
Highway Capacity Manual ◽  
Percent Time ◽  
Explained Variation ◽  
Surrogate Measure

According to the Highway Capacity Manual (HCM), it is possible to quantify level of service for rural highways using a basic parameter: percent time delay. Since this variable cannot be measured, it is proposed in the HCM that the percentage of delayed vehicles (% DV) be used as a surrogate measure. The manual gives no means of predicting or estimating % DV other than a curve relating total % DV to total hourly volume. However, it is worth noting that the methodology proposed in the manual does not use this curve. In any case, there has been to this date no proposal as to the estimation of % DV by traffic direction. The results of an attempt to estimate % DV by direction through multiple correlations are presented. The data were gathered on four highways in the province of Madrid, Spain (M-111, M-501, M-600, and M-607). Measurements were carried out in 3-h periods on plain or slightly sloping ground during daily or weekly peak periods. The average daily traffic and rate of heavy vehicles in 1991 were, sorted chronologically, 9,500 and 6.4 percent for M-607; 9,800 and 5.1 percent for M-600; 8,100 and 8.6 percent for M-111; and 14,400 and 5.0 percent for M-501. Several multiple correlations are offered, and one is chosen that has an accuracy of 0.7964, expressed through the coefficient r2 (the explained variation). The model is % DV (Direction 1) = A * (VDirection1) + B * (VDirection2) + C, with the following numerical values: % DV = 0.0443 * V1 + 0.0096 * V2 + 25.5411.

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.

Modeling and Validating Traffic Responsive Ramp Metering in the Highway Capacity Manual Context

2020 ◽  
Vol 2674 (12) ◽  
pp. 91-102
Author(s):  
Seyedbehzad Aghdashi ◽  
Joy Davis ◽  
Thomas Chase ◽  
Chris Cunningham
Keyword(s):  
Demand Management ◽  
Vital Role ◽  
Performance Measure ◽  
Ramp Metering ◽  
Travel Time Reliability ◽  
Highway Capacity ◽  
Sixth Edition ◽  
Highway Capacity Manual ◽  
User Input ◽  
And Performance

This paper presents a methodology for modeling traffic responsive (or adaptive) ramp metering in the freeway facilities method based on the sixth edition of the Highway Capacity Manual (HCM6). Currently, the HCM only provides an option to meter on-ramps as user input using 15-min average flow rates with a focus on planning-level analyses. As a result, the possibilities for simulating and modeling ramp meters with any traffic responsive ramp metering algorithm in the HCM context are limited. Moreover, the freeway facilities methodology in the HCM plays a vital role in the analysis of travel time reliability, which is built on a set of operational scenarios. However, with the lack of traffic responsive ramp metering, analysts are burdened with the task of manually entering average effective ramp metering rates for each on-ramp within the set of reliability scenarios. This process can require a substantial amount of time, in addition to increasing the potential for inaccuracy and bias in freeway and performance measure estimations. As a result, this paper is designed to fill a significant research gap by providing a method for analyzing traffic responsive (or adaptive) ramp metering, an active traffic and demand management strategy, using the core freeway facilities methodology in the HCM. The direct application of the method focuses on the MaxView metering algorithm. However, the proposed framework can be used to model any traffic responsive ramp metering algorithm. The results are validated using real-world sites located on the I-540 westbound freeway corridor in North Carolina.

scholarly journals PERCENT TIME-SPENT-FOLLOWING MODEL FOR SINGLE CARRIAGEWAY ROAD

2019 ◽  
Vol 81 (6) ◽  
Author(s):  
Lee Vien Leong ◽  
Shafida Azyanti Mohd Shafie ◽  
Wins Cott Goh
Keyword(s):  
Performance Indicator ◽  
Threshold Value ◽  
Video Camera ◽  
Performance Measure ◽  
Threshold Values ◽  
Heavy Vehicles ◽  
Percent Time ◽  
Indicator Analysis ◽  
And Performance ◽  
Percent Time Spent Following

 Percent time-spent following (PTSF) is an important parameter in determining level-of-service of a single carriageway road but the current performance measure adopted in Malaysia is based on volume over capacity (v/c) ratio. Therefore, this study aims to develop a new PTSF model that is suitable for single carriageway roads in Malaysia. Traffic flow at 32 sites in various states in Malaysia were recorded using CCTV and video camera. Image processing software was used to extract volume, speed and headway data. Surrogate measure which is the percentage of vehicles travelling with headway threshold values of 3.0 and 5.0 seconds were used in estimating PTSF in the field. Initially, the base PTSF (BPTSF) model was developed and subsequently used to develop six different PTSF models using headway threshold values of 3.0 and 5.0 seconds and different variables. Analyses and performance indicators showed that the model developed based on the headway threshold value of 5.0 seconds with the inclusion of percentage of no-passing zone, opposing flow rate and percentage of heavy vehicles is the best model. This model was determined as the best fit as it has the highest score of 15, which is the maximum score based on performance indicator analysis.

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