Citation

Wiorkowski JJ, Heckard RF. Accid. Anal. Prev. 1977; 9(4): 229-247.

Copyright

(Copyright © 1977, Elsevier Publishing)

DOI

unavailable

PMID

unavailable

Abstract

The analysis of time series data expoused by G.E.P. Box and G.M. Jenkins is introduced and motivated within the context of time series data collected on traffic indices. Simple models for a set of six traffic indices collected for the State of Texas are developed. During the time period spanned by these series two significant events occurred. A fuel shortage was experienced in the months of February and March 1974 and in February of 1974 the maximum speed limit on all roads in the state was lowered to 55 miles per hour. Using the methods of intervention analysis developed by G.E.P. Box and G. Tiao, the magnitude of the effects of these two factors on the traffic indices in the state were assessed. It is shown that the combined effect of the fuel shortage and the speed limit reduction induced significant shifts in the course of the traffic series and that the effects of the speed limit reduction have persisted but are diminishing over time.