Determining optimum speed limit reduction in freeway work zones

Abstract

<p>This study aims to propose a set of procedures to establish the optimum speed limit reduction to be deployed at freeway work zones across Iowa. These work zones are classified as traffic critical work zones by the Iowa Department of Transportation due to their high average annual daily traffic, potential to cause major traffic hindrances and delays in the event of an incident, and presence of state border bridges. Due to the severe impacts these work zones pose on the operating traffic, it is imperative to quantify the safety risk associated with such construction operations both from the standpoint of crash frequency, as well as total damage incurred, in other words, crash severity.</p> <p>As work zones on freeways are a dynamically progressing operation, it is often difficult to extract exact information regarding the specific construction activity in place at any specific point in time. A number of transient variables which are expected to be major influencers of crash counts and crash severities are often challenging to ascertain, rendering the work zone characteristic database relatively fuzzy. The primary goal of this study was to mine the highest resolution detail about the work zones possible through the available resources and by linking it to other typical traffic safety metrics, envisage the effect of various categories of speed limit drops on the frequency and severity of crashes.</p>