As noted earlier in this issue of Fleet Owner, the debate over truck size and weight has recently re-emerged in Congress and an understanding of the background behind this debate is critical, since you will hear much “puffery” on the topic in the coming months.

Despite several legislative opportunities during the past 10 years, Congress has not made any revisions to federal truck weight standards, which were frozen at 80,000 lbs. by the Intermodal Surface Transportation Efficiency Act in 1991.

Some say this debate may result in a favorable outcome. Diesel fuel prices, for example, are squeezing motor carriers like no other time in history. The rail industry is also said to be less vocal about its opposition. That being said, many forces will oppose any attempt at increased size and/or weight limits.

Generally, the opposition over increased truck productivity centers around two key areas: increased highway/bridge wear and decreased truck safety. I'd like to review a few of the truck safety issues, since opponents have already gone on record stating that “bigger, heavier, longer trucks are more dangerous.”

Trucks can become more “productive” by employing either or both of two vehicle configurations: multiple-trailer longer combination vehicles (LCVs) and single-trailer combinations with three-trailer axles and a gross combination weight to 97,000 lbs.

Generally, policymakers and researchers examine four operating characteristics of these configurations when assessing safety impact:

Roll stability — Assesses the likelihood of a vehicle rollover when conducting a “steady-state” turn, such as negotiating a curve or freeway exit ramp.

Lateral stability — Assesses the likelihood of a jackknife or skid from a “side-to-side” evasive maneuver such as avoiding a highway obstruction.

Stopping distance — Generally measured as the total time/distance from highway cruising speed to a full stop.

Off-track — Measures the change in trailer “following path” as trailer length increases.

Much research has been conducted in assessing operating characteristics of various configurations. Federal Highway Administration research has revealed a decrease in both roll and lateral stability and stopping distance with LCV configurations. This same research, however, revealed that six-axle, 97,000-lb. single-trailer configurations exhibited increased lateral stability and only minor degradations in roll stability and stopping.

This single-trailer configuration has been endorsed by a stakeholder group known as Americans for Safe and Efficient Transportation. Their testimony also observed that such a combination would result in fewer vehicle miles traveled and thus fewer truck crashes.

Despite the facts, it will be a very difficult debate. Jim Oberstar (D-MN), House Transportation and Infrastructure Committee chairman, previously has been skeptical of such an approach, and other advocates will vehemently oppose any increase.

I urge you to become conversant in the issues. Read the research so that you can separate fact from fiction. The Comprehensive Truck Size and Weight Study is posted at www.fhwa.dot.gov/policy/otps/truck. Additional safety research is available on the Transportation Research Board site at www.trb.org.


Jim York is the ass't. vice president of technical services for Zurich Services Corp. Risk Engineering in Schaumburg, IL.