Truck Size and Weight Issues

This paper emphasizes the information obtained from the 1977 truck weight study concerning overweight trucks presently traveling on Indiana highways, specifically the 3-S2 and 3-S3 trucks, and presents the results of a study conducted at Purdue concerning the effect of increasing truck weights limits from 73,280 to 80,000 lbs. gross on pavement maintenance costs. Based on this study, the following conclusions can be made: (1) It is very difficult for the state of Indiana to enforce the weight limits adopted from the Federal Aid Highway Act of 1956 since three out of the four states that surround Indiana have adopted those weight limits established by the Federal Aid Highway Act of 1974; in addition, one state is protected under the grandfather clause which permits loads in excess of those specified by the Act; (2) Overweight trucks cause an increase in highway deterioration (decrease in the life of the pavement) as well as an increase in routine maintenance costs; and (3) Increase in truck weight limits from 73,280 lbs. to 80,000 lbs. gross will cause an increase in maintenance costs for the total state mileage between 10.43 and 12.15 million dollars annually in 1978 dollars. This increase depends largely on the effect of the present energy shortage mainly of petroleum which greatly influences the cost of asphalt concrete.