Abstract

This paper presents a comparative analysis of the level-of-service (LOS) determination based on the VISSIM simulation software and technique described in Highway Capacity Manual (HCM). The methodology used in the analysis is that of the level of service determination for road transport network as exemplified by T-shape intersection and partial cloverleaf (parclo AB3) interchange in the city of Kryvyi Rih. The Department of Road Safety of the National Patrol Police of Ukraine set the task to determine the vehicles queuing length on the bridge if traffic lights at the T-shape intersection are installed. To conduct the project, the VISSIM simulation model of the intersection was developed according to site data collection on workdays and at weekends. LOS criteria were determined by using both traffic management assessment methods. The scenario of traffic lights installation at the intersection was elaborated. It was determined that with traffic signalization adjustment the average travel speed would be about 40% of the free flow speed for a street class. The two assessment methods vary significantly regarding traffic flow density criterion (35.1%). The conclusion is that flow density criterion is not reliable for the node LOS definition. By way of application value of the research findings the recommendations have been prepared for T-shape intersection traffic management that dismissing the project of traffic lights installation at the intersection needs to be considered.

Abstract

A not clear national framework and the uncertainty as to the transferability of the U.S. HCM require an assessment of standard methodologies more calibrated on Italian freeways. The study is aimed at testing the Levels of Service assessment for a sample freeway segment on the basis of a calibrated Fundamental Diagram, and at evaluating its consistency with respect to the most recent methodologies from HCM2010. The research shows a test calibration of the Fundamental Diagram according to the Longitudinal Control Model and Van Aerde Model. The comparative analysis shows how standard procedures and ranges could underestimate operational congestion levels on the test section. Therefore, the results suggest that operators should to use carefully HCM standard procedures and that transferability issues should be further analyzed.