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Development of a delay model for unsignalized intersections applicable to traffic assignment

Shahpar, A. H ; Sharif University of Technology | 2011

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  1. Type of Document: Article
  2. DOI: 10.1080/03081060.2011.586119
  3. Publisher: 2011
  4. Abstract:
  5. This paper develops a model for estimating unsignalized intersection delays which can be applied to traffic assignment (TA) models. Current unsignalized intersection delay models have been developed mostly for operational purposes, and demand detailed geometric data and complicated procedures to estimate delay. These difficulties result in unsignalized intersection delays being ignored or assumed as a constant in TA models. Video and vehicle license plate number recognition methods are used to collect traffic volume data and to measure delays during peak and off-peak traffic periods at four unsignalized intersections in the city of Tehran, Iran. Data on geometric design elements are measured through field surveys. An empirical approach is used to develop a delay model as a function of influencing factors based on 5- and 15-min time intervals. The proposed model estimates delays on each approach based on total traffic volumes, rights-of-way of the subject approach and the intersection friction factor. The effect of conflicting traffic flows is considered implicitly by using the intersection friction factor. As a result, the developed delay model guarantees the convergence of TA solution methods. A comparison between delay models performed using different time intervals shows that the coefficients of determination, R2, increases from 43.2% to 63.1% as the time interval increases from 5- to 15-min. The US Highway Capacity Manual (HCM) delay model (which is widely used in Iran) is validated using the field data and it is found that it overestimates delay, especially in the high delay ranges
  6. Keywords:
  7. Traffic assignment ; Un-signalized intersection ; Delay models ; Empirical approach ; Field data ; Friction factors ; Geometric data ; Geometric design ; Highway Capacity Manual ; Influencing factor ; Model estimates ; Number recognition ; Solution methods ; Tehran ; Time interval ; Traffic flow ; Traffic periods ; Traffic volume data ; Traffic volumes ; Vehicle license plates ; Estimation ; Friction ; Highway engineering ; Intersections ; Optical character recognition ; Street traffic control ; Highway traffic control ; Comparative study ; Empirical analysis ; Field survey ; Geometry ; Model validation ; Numerical model ; Traffic management ; Urban transport ; Iran ; Tehran [Iran]
  8. Source: Transportation Planning and Technology ; Volume 34, Issue 5 , Jun , 2011 , Pages 497-507 ; 03081060 (ISSN)
  9. URL: http://www.tandfonline.com/doi/abs/10.1080/03081060.2011.586119