Examining the effect of truck traffic on the safety of various road classifications

Roadway safety is an integral part of a functioning infrastructure. Many types of vehicles use the highway system for a variety of purposes, and each affects the roadways differently. Aside from commuter traffic and leisurely travel, a major use of the highway system is the transport of goods. These goods are typically transferred in large trucks. As supply and demand grows, the amount of trucks on the roadways needed to transport goods increases. The United States has experienced constant growth in the amount of freight transported by truck in the last few years.;While overall national freight growth is constant, localized effects are more varied. Freight traffic may spike in areas based on events such as a new factory, or the discovery of a natural resource. These additions to a localized area can be taxing on the citizens and infrastructure, and the effect that truck traffic has on these areas may be more concentrated. The state of Wyoming has begun to experience a large increase in truck traffic on some of its local and county roads due to an increase in oil and gas production.;The primary measure to evaluate the safety of a roadway is the number of crashes. This study addresses the effect that large truck traffic is having on the safety of various road sizes and classifications. For this study, large trucks are defined as vehicles weighing more than 26,000 pounds and the safety is measured by a crash's severity. An investigation on past literature revealed that many studies have been done on the factors involved in and the causation of heavy truck crashes, but none address the causation and effect the truck crashes have on different types of areas. Answers to this question may give transportation engineers guidelines on how to address truck safety in specific types of areas.;A descriptive analysis of statewide crash data revealed many different trends in crashes. Most truck crashes occurred on interstates and primary federal highways. When road conditions were not clear, crashes more often occurred when snowy weather and icy roads were present. Heavy trucks were involved in multi-vehicle crashes less often than passenger vehicles. To verify some of the effects from the descriptive analysis, a logistic regression model was used to further explore the results. A localized study was also conducted to acquire better knowledge of the effect that trucks were having on local roads. This crash analysis focused on four counties in Eastern Wyoming and found that where truck traffic volumes have been increasing, so have crash rates in those counties.