Road Weather Management Program
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Best Practices for Road Weather Management Version 2.0

Title:

Potential Effects of Wet Conditions on Signalized Intersection LOS

Abstract:

Although rain and other precipitation is common, analyses of signalized intersections based on the Highway Capacity Manual require clear weather and dry pavement conditions. Three factors may be affected by wet weather: saturation flow, effective green time and progression. Saturation headway may lengthen, effective green may shrink and progression may worsen in wet conditions. As a result, signalized intersection operations become less efficient. This is demonstrated in the longer delays estimated for five sample intersections. A methodology was developed for the derivation of the probability of rainfall during the morning and evening peak hour for any intersection in the U.S. using readily available rainfall accumulation data from NOAA. Once delay and LOS are estimated for both dry and wet conditions, a weighted average is employed for estimating delays and LOS that represent the prevailing dry and wet peak period conditions at a signalized intersection.

Source(s):

ASCE Journal of Transportation Engineering; University of Hawaii-Manoa, Department of Civil Engineering. For an electronic copy of this resource, please direct your request to WeatherFeedback@dot.gov.

Date: 2004

Author:

Prevedouros, Chang

Keywords:


Mobility
Pavement condition
Rain
Traffic modeling
Traffic signal
Precipitation

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