Longer Combination Vehicles: Do They Improve Freight Flows and Operational Efficiency and Reduce Highway Congestion?

Quarterly Reports Other Documents Final Report
September 2011
December 2011
Research Brief Final Report

Primary Investigators

Teresa Adams, Bob Gollnik, and Jason Bittner
University of Wisconsin-Madison
1415 Engineering Drive
2205 Engineering Hall
Madison, WI 53706


Longer combination vehicles (LCVs) are attractive for the transportation community because they carry more freight per trip. However, the implications, costs and benefits of LCVs are not clearly delineated or well documented. An initial evaluation suggests the benefits include improved freight flow (more freight per driver), improved administrative efficiency (fewer permits required), and reduced highway congestion (fewer trucks on the road). However a more comprehensive evaluation is required to account for safety concerns, traffic impacts, liability costs, and potential infrastructure damage. In some circumstances special equipment and higher wages for qualified drivers could offset the potential operational efficiency. Furthermore, if LCVs lower freight costs, trucking may be a more competitive alternative to rail at some distances thus increasing highway congestion. This project analyzes these potential tradeoffs and will create a spreadsheet tool for evaluating the cost-benefit analysis of LCV operations on a highway corridor.


This research will provide an objective and comprehensive evaluation of how the use of LCVs will impact freight flow, operational efficiency, safety, infrastructure, and highway congestion. The results of this project will contribute to the policy evaluation that will determine whether to continue to restrict or allow for operation of LCVs on state and federal highways. If the federal freeze is lifted in the future, this research will be useful to individual states for policy and project evaluation, pricing, or cost allocation decisions relative to the operation of LCVs within their state. Policy makers at all levels of government could potentially use the results of this research. The benefits will be measured objectively by evaluating the safety of LCVs and the amount of pavement damage they cause. The benefits will also be measured by conducting interviews and discussions with state agencies, private business, and motor carriers. The research team will provide a reasonable estimate of the amount of truck traffic that would be influenced by increased LCV usage.


  1. Identify issues and parameters.
  2. Develop ranked preferences for LCV operations and objectives.
  3. Develop a benefit-cost analysis (BCA) template.
  4. Discuss regional and national implications.
  5. Final reporting.

Project Information

  • Duration: 12 months
  • Dates: January 1, 2011 – September 30, 2011
  • Budget: $50,007
  • Student Involvement: One graduate student
  • Modal Orientation: Highway
  • Project ID: CFIRE 05-01
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