This report describes the application of Bayesian statistical methods to several related problems arising in the estimation
of mean daily traffic for roadway locations lacking permanent automatic traffic recorders. A lognormal regression model
is fit to daily count data obtained from automatic traffic recorders, and this model is then used to develop (1) a heuristic
algorithm for developing traffic sampling plans which minimize the likelihood of assigning a site to an incorrect factor
group, (2) an empirical Bayes method for assigning a short-count site to a factor group using the information in a sample
of traffic counts, and (3) an empirical Bayes estimator of mean daily traffic which allows for uncertainty concerning the
appropriate factors to be used in adjusting a sample count. An evaluation of these methods confirmed results reported
in other work, in which a sample consisting of two, 1-week counts was found to be adequate for overcoming prior
uncertainty concerning the correct adjustments for a site. The empirical Bayes method produced sample-based estimates
of mean daily traffic that on the average differed by 5%-6% from estimates based on daily counts for an entire year.
The report concludes with suggestions for agencies wishing to implement these methods.
Davis, Gary A..
Estimation theory approach to monitoring and updating average daily traffic: final report.
Minnesota Department of Transportation.
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