Analysis of Major Freeway Incidents in Houston, Texas

An analysis of major freeway incidents in Houston, Texas, was conducted. The data base analyzed was provided by the Houston Police Department solo motorcycle patrol division. This division responds to all freeway lane-blocking incidents that are expected to last more than approximately 45 minutes. Over a 7-year period between 1986 and 1992, the division documented the details of 612 major freeway incidents to which it responded. From these data, it was estimated that major freeway incidents occur in Houston at a rate of 0.68 incident per 100 million vehicle-kilometers (MVK). That is equivalent to a major incident every 147 MVK. Major incidents were nearly 3.5 times as likely to occur within the interchanges (based on vehicle-kilometers driven) as between them. Of the 612 major incidents included in the data base, 498 (81.5 percent) involved trucks only (even though large truck traffic accounts for only 7.7 percent of the total vehicle-kilometers traveled on Houston freeways). Furthermore, lost or spilled loads and truck overturns account for nearly one-half of the major incidents in Houston. Information on incident severity and duration is also presented.