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

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.

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.

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.

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. 

Computational Techniques Used in the Driver Performance Model of the Interactive Highway Safety Design Model

2001 ◽  
Vol 1779 (1) ◽  
pp. 17-25 ◽  
Author(s):  
William H. Levison ◽  
Ozgur Simsek ◽  
Alvah C. Bittner ◽  
Steven J. Hunn
Keyword(s):  
Computer Aided Design ◽  
Driving Simulator ◽  
Research Area ◽  
Highway Safety ◽  
Performance Model ◽  
Design Model ◽  
Computational Techniques ◽  
Design Environment ◽  
Driver Performance ◽  
Safety Design

The Interactive Highway Safety Design Model (IHSDM) is a high-priority research area for FHWA. IHSDM is a software system for evaluating the safety of alternative highway designs in a computer-aided design environment. The initial phase of this research program is to develop IHSDM for use in the design of two-lane rural highways. IHSDM includes a driver-vehicle module that simulates the moment-to-moment actions of a single driver-vehicle unit. Reviewed are the computational approaches that have guided the implementation of the driver performance model (DPM) that along with a vehicle model and other components constitute the driver-vehicle module. Five major computational functions of DPM are reviewed: perception, speed decision, path decision, speed control, and path control. Comparison of model results with data from a driving simulator demonstrates the ability of DPM to account for the horizontal curve deflection angle on the speed profile.

Empirical Investigation of Interactive Highway Safety Design Model Accident Prediction Algorithm: Rural Intersections

2003 ◽  
Vol 1840 (1) ◽  
pp. 78-86 ◽  
Author(s):  
Craig Lyon ◽  
Jutaek Oh ◽  
Bhagwant Persaud ◽  
Simon Washington ◽  
Joe Bared
Keyword(s):  
Research Effort ◽  
Methodological Approach ◽  
The United States ◽  
Highway Safety ◽  
Design Model ◽  
Prediction Algorithm ◽  
Parameter Estimates ◽  
Wide Range ◽  
Safety Design ◽  
The Impact

One major gap in transportation system safety management is the ability to assess the safety ramifications of design changes for both new road projects and modifications to existing roads. To fulfill this need, FHWA and its many partners are developing a safety forecasting tool, the Interactive Highway Safety Design Model (IHSDM). The tool will be used by roadway design engineers, safety analysts, and planners throughout the United States. As such, the statistical models embedded in IHSDM will need to be able to forecast safety impacts under a wide range of roadway configurations and environmental conditions for a wide range of driver populations and will need to be able to capture elements of driving risk across states. One of the IHSDM algorithms developed by FHWA and its contractors is for forecasting accidents on rural road segments and rural intersections. The methodological approach is to use predictive models for specific base conditions, with traffic volume information as the sole explanatory variable for crashes, and then to apply regional or state calibration factors and accident modification factors (AMFs) to estimate the impact on accidents of geometric characteristics that differ from the base model conditions. In the majority of past approaches, AMFs are derived from parameter estimates associated with the explanatory variables. A recent study for FHWA used a multistate database to examine in detail the use of the algorithm with the base model-AMF approach and explored alternative base model forms as well as the use of full models that included nontraffic-related variables and other approaches to estimate AMFs. That research effort is reported. The results support the IHSDM methodology.

scholarly journals Travel Time Estimation on Urban Street Segment

2018 ◽  
Vol 30 (1) ◽  
pp. 115-120 ◽  
Author(s):  
Jelena Kajalić ◽  
Nikola Čelar ◽  
Stamenka Stanković
Keyword(s):  
Travel Time ◽  
Time Estimation ◽  
Travel Speed ◽  
Degree Of Saturation ◽  
Level Of Service ◽  
Travel Time Estimation ◽  
Highway Capacity ◽  
Local Conditions ◽  
Highway Capacity Manual ◽  
Urban Streets

Level of service (LOS) is used as the main indicator of transport quality on urban roads and it is estimated based on the travel speed. The main objective of this study is to determine which of the existing models for travel speed calculation is most suitable for local conditions. The study uses actual data gathered in travel time survey on urban streets, recorded by applying second by second GPS data. The survey is limited to traffic flow in saturated conditions. The RMSE method (Root Mean Square Error) is used for research results comparison with relevant models: Akcelik, HCM (Highway Capacity Manual), Singapore model and modified BPR (the Bureau of Public Roads) function (Dowling - Skabardonis). The lowest deviation in local conditions for urban streets with standardized intersection distance (400-500 m) is demonstrated by Akcelik model. However, for streets with lower signal density (<1 signal/km) the correlation between speed and degree of saturation is best presented by HCM and Singapore model. According to test results, Akcelik model was adopted for travel speed estimation which can be the basis for determining the level of service in urban streets with standardized intersection distance and coordinated signal timing under local conditions.

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