The state of New Jersey enacted two regulations with significant importance to the highway operations: 65 mph speed limit and truck restriction on the National Network. The speed limit of 65mph was used on limited sections of interstate system highways with an objective to reduce energy consumption by vehicles and truck restriction was used on the interstate system and other state highway system to reduce large truck accidents and thereby increase truck safety. In this research, the safety impacts of these two regulations on truck crashes were studied.

The research focused on monthly truck crashes along the highway sections where the regulations were implemented to determine whether there was an increase or decrease in truck crashes. In addition to simple before-after average comparisons, a complex time series method was used to analyze the monthly truck statistics. The effect of regulation was analyzed as an intervention parameter in a Box-Jenkins Auto Regressive Integrated Moving Average (ARIMA) model of monthly truck crashes along entire routes and section of the routes. In general, the results were inconclusive.