Development of Capacity Model for Urban Arterials using VISSIM

Traffic is heterogeneous in all countries in the world including US but the degree of heterogeneity is different in developing and developed countries. The Highway capacity manual (HCM 2010) of US has defined two categories of vehicles visually car and heavy vehicles. However, in the car category there are many models like hatchback, sedan, sport utility vehicle (SUV) and XUV are plying on the road whereas in the heavy vehicle category, bus, two and three axle trucks are there on the roads. The operating and physical characteristics of these vehicles are different and they affect the speed flow characteristics of the stream at different flow levels thus consequently affect the capacity of the roadway. The present paper demonstrates the effect of traffic mix on capacity of urban arterial roads and proposes a mathematical model to determine capacity of six-lane divided urban arterial at different composition of various categories of vehicles present in the traffic stream. Microscopic simulation software VISSIM is used to develop the model. Speed flow characteristics of various categories of vehicles are studied in the field and are used to calibrate and validate the software for mixed traffic conditions. Traffic data collected in field are used to derive capacity of the road in terms of equivalent passenger car unit (PCU) per hour. The capacity of six-lane road as achieved from the field data is 6300 PCU/hr for one direction of traffic flow. This capacity value was further achieved through simulation run for ‘all car’ conditions using calibrated VISSIM software. The program was run for small car and one of the remaining four categories of vehicles at different compositions in the traffic stream. Regression equations were developed for each set of simulation run for all four categories of vehicle with standard car. These equations are then combined to develop the capacity model. Further, a stream equivalency factor (SEF) is developed that can be used to convert heterogeneous traffic stream into homogeneous equivalent without actually using the passenger car units (PCU) values. The proportion of each category of vehicle in the traffic mix and total vehicle volume in veh/hr is taken as independent variable in developing SEF model. Two models have been proposed in the study. The capacity model may be used for quick estimation of volume to capacity (v/c) ratio which is the surrogate measures of level of service (LOS) on the roadway and at the same time capacity of a roadway can be determined in pcu/hr using SEF model without actually using the PCU factors. Similar models may develop for US conditions when variety of vehicles is present in the traffic mix.

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• Supplemental Notes:
  • This paper was sponsored by TRB committee AHB40 Standing Committee on Highway Capacity and Quality of Service.
• Corporate Authors:

  Transportation Research Board

  500 Fifth Street, NW
  Washington, DC  United States  20001
• Authors:
  • Dhamaniya, Ashish
  • Chandra, Satish
• Conference:
  • Transportation Research Board 96th Annual Meeting
  • Location: Washington DC, United States
  • Date: 2017-1-8 to 2017-1-12
• Date: 2017

Language

• English

Media Info

• Media Type: Digital/other
• Features: Figures; References; Tables;
• Pagination: 17p
• Monograph Title: TRB 96th Annual Meeting Compendium of Papers

Subject/Index Terms

• TRT Terms: Arterial highways; Highway capacity; Level of service; Passenger car equivalence; Simulation; Sport utility vehicles; Traffic models; Urban highways; Vehicle mix
• Subject Areas: Highways; Planning and Forecasting;

Filing Info

• Accession Number: 01628711
• Record Type: Publication
• Report/Paper Numbers: 17-03208
• Files: PRP, TRIS, TRB, ATRI
• Created Date: Mar 9 2017 9:14AM