Operational Characteristics of Longer Combination Vehicles and Related Geometric Design Issues

As the size and configuration of trucks operating on public highways continues to change, how these vehicles operate needs to be better understood to accommodate them through better geometric designs or regulate them through more stringent laws and better enforcement. Longer-combination vehicles (LCVs), a group that includes Rocky Mountain doubles, turnpike doubles, and triples, fall into this category. LCVs handle and perform differently from tractor semitrailers or twin trailers because of their increased lengths and weights. These differences in handling and performance may jeopardize the safety of the LCV as well as other vehicles on the roadway. Several of the LCV's operational characteristics are believed to have an impact on transportation safety and the relationship of these characteristics to geometric design. There is a clear need to conduct additional research to further evaluate LCV operations. Several such research efforts are recommended.