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

Title:

Temporary Losses of Highway Capacity and Impacts on Performance

Abstract:

The Temporary Loss of Capacity (TLC) study develops estimates of highway capacity losses and delay caused by transitory events, such as construction work zones, crashes, breakdowns, extreme weather conditions, and sub-optimal traffic controls. The scope of the study includes all urban and rural freeways and principal arterials in the nation's highway system. Capacity losses and delay resulting from three broad weather categories were estimated: fog, snow, and ice. Due to time and funding limitations, capacity losses and delays due to rain were not included in the study. The study also does not consider any trip re-scheduling or canceling behavior in its delay estimates. The TLC study estimated that, in 1999, fog, snow, and icy conditions reduced capacity on freeways and principal arterials by approximately 24 billion vehicles. This resulted in an estimated 543.9 million vehicle-hours of delay. Most of this estimated delay (90 percent) was due to snow in urban areas. Icy conditions accounted for 7 percent of the estimated delay from these weather conditions, and fog accounted for about 3 percent.

Source(s):

Oak Ridge National Laboratory and University of Tennessee

http://www-cta.ornl.gov/cta/Publications/Reports/ORNL_TM_2002_3.pdf

Date: 2002

Author:

Chin, et al

Keywords:


Fog
Snow
Ice/Frost
Mobility
Precipitation
Visibility

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