Gary A.
Davis
Department of Civil Engineering
University of Minnesota
Minneapolis, MN
TRB Preprint Paper No. 970984
January 1997
A location's mean daily traffic (MDT) is the expected traffic volume on a "typical" day, and the AASHTO Guidelines for Traffic Data Programs identifies 22 different uses for estimates of MDT. This paper reviews the problem of quantifying the "precision and bias" of site-specific, short-count estimates of MDT, with particular attention to the different sources of estimation error. It is argued that earlier attempts to determine the likely error of short count estimates did not include error due to use of incorrect adjustment factors, and it is then pointed out that incorrect adjustment can produce very substantial increases in estimation error. Research on managing such adjustment errors is reviewed, leading to the conclusion that seasonal, rather than simple coverage, counts may be needed to produce good estimates of MDT.
key words:
average daily traffic, traffic congestion, traffic volume
This document is available to the public through the Transportation Research Board, Washington, D.C. 20418.
Last Modified: March 20, 2007
Maintained by: traffic@nmsu.edu
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