Volume counting for computing delay at signalized intersections
The 1985 Highway Capacity Manual (HCM) uses computed stopped delay to determine the levels of service (LOS) for lane groups at signalized intersections. These computations utilize volume (v) and capacity (c) in computing overflow stopped delay. Although the new HCM specifies use of arrival volumes for the computation of overflow delay, it does not explain how to obtain arrival volumes for saturated approaches. This article suggests procedures to follow to obtain arrival volumes for a lane group when the v/c value for a lane group approaches or exceeds 1.0. In the Input Module of the Methodology section of the HCM chapter on signalized intersections, traffic volumes are to be obtained for each movement by type of vehicle. These volumes are then adjusted in the Volume Adjustment Module to reflect peak 15-minute flow rates by use of a peak-hour factor (PHF). Lane groups are selected for use in the capacity and LOS analyses, and adjustments are made for lane utilization. Details are not provided on how to select the 15-minute period with the highest volume or how to determine arrival volumes during the peak 15 minutes.
- Research Organization:
- Emeritus of Transportation Engineering at Northwestern Univ. (US)
- OSTI ID:
- 5006419
- Journal Information:
- ITE J.; (United States), Journal Name: ITE J.; (United States) Vol. 57:3; ISSN ITEJD
- Country of Publication:
- United States
- Language:
- English
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