Ahead of the House voting this week on the T-HUD bill that would legalize “twin 33” trailers nationwide, the Department of Transportation declared that “data limitations” uncovered by its research on the impact of increasing truck size and weight limits should at this point preclude changing “relevant laws and regulations.”

To be clear, the Federal Highway Administration has not yet completed the Comprehensive Truck Size and Weight Limits Study required by the current highway bill (MAP-21). Rather, DOT has released five technical reports on specific areas the agency looked into “for peer review and public comment as a major step moving toward the completion of the comprehensive study called for” by Congress.

The department noted that MAP-21 directed it to study the issues associated with trucks operating within and in excess of current size and weight limits and the impact on safety, pavement and bridge deterioration, enforcement and shifts to other transport modes, such as rail. 

In a June 5 letter to Congress detailing the informational deficiency, DOT Under Secretary for Policy Peter Rogoff said that the research effort “revealed very significant data limitations that severely hampered the Federal Highway Administration’s efforts to conclusively study the effects of the size and weight of various truck configurations.”

He advised that FHWA was hampered by the lack of descriptive information in truck-crash reports and by the lack of publicly available data on the modal shift of freight to short-line and regional railroads.

Rogoff said the agency also found a “profound absence” of weight data in crash reporting; a lack of models to predict bridge-deck deterioration over time; and the difficulty of distinguishing the cost of truck-weight enforcement from that of overall truck-safety enforcement costs.

 “At this time, the department believes that the current data limitations are so profound that the results cannot accurately be extrapolated to predict national impacts,” Rogoff summed up. “As such, the department believes that no changes in the relevant truck size and weight laws and regulations should be considered until these data limitations are overcome.”

FHWA next step as it works to complete its mandated report will involve meeting with an “independent peer review team,” managed by the Transportation Research Board (TRB), as well as seeking public comment. According to DOT, despite the data shortcomings uncovered, the technical reports on size and weight “provide an opportunity for experts in the field to comment in anticipation of the final report to Congress.”

The American Trucking Associations declared that the release of the “self-acknowledged incomplete study [was] timed to color [the] current debate” on truck size/weight reform.

“Given the timing of the release of this study, it is an obvious attempt to promote administration policy, rather than give Congress the unbiased information it requested,” said ATA President and CEO Bill Graves. “It is appalling that after years of saying the study would not make recommendations, DOT officials would release this report – and recommend no change in current law – just days after the White House came out opposing truck productivity increases.”

On the other hand, Graves said that “as flimsy as this report is, it at least acknowledges these more productive combinations will improve efficiency, saving American consumers billions of dollars. We will continue reviewing DOT’s report to see how it arrived at conclusions that are so different from our industry’s experience and previous research in this area, including the Transportation Research Board’s 2002 investigation, which recommended nationwide operation of 33-foot double trailers.”

The Coalition for Transportation Productivity, a group of 200 shippers and allied associations that lobbies for increasing the federal vehicle weight limit on Interstate highways, said it “welcomed” the data released by DOT as it supports its drive for “six-axle truck weight reform.”

According to CTP, the FHWA study’s technical finding evaluate a range of truck configurations, including those contained in the Safe and Efficient Transportation Act-- which the group said would give each state the option to set higher Interstate weight limits for trucks outfitted with six axles instead of five.

“The U.S. DOT findings can be added to the growing list of state, federal, international and academic research confirming the safety and efficiency benefits of the Safe and Efficient Transportation Act,” said CTP Executive Director John Runyan. “In fact, this DOT data debunks several major points of opposition to six-axle truck weight reform, affirming that the Safe and Efficient Transportation Act configuration is safe, more productive and would reduce vehicle miles traveled without any significant shift of freight from rail.”

Per Runyan, “significant DOT conclusions regarding heavier six-axle trucks” within the technical reports just released include these six points:

• The modal shift is principally from truck to more productive trucks and would result in overall lowering of vehicle miles traveled by trucks (Vol. 1 ES-5).

• Total logistics costs for transporting freight would decline (Vol. 1 ES-5).

• More productive trucks lower congestion costs, fuel costs, and carbon and other emissions (Vol. 1 ES-6).

• Truck weight reform would yield considerable pavement cost reductions (Vol 1 ES-8)

• Vehicle stability and control virtually are unchanged on heavier six-axle vehicles (Vol. 1 ES-11).

• Bridge impacts could be addressed through posting, modest investment or fees (Vol 1 ES 8, 11).

“DOT officials began this study process with the intention to only release technical findings and make no policy recommendations,” Runyan also pointed out. “The department’s inability to endorse gross vehicle weight reform without a more robust study is neither surprising nor unexpected, especially given the highly charged atmosphere surrounding this study…  It is now up to Congress to decide if heavier six-axle vehicles, which clearly have few negatives and many positives, can be utilized to address the capacity crisis.”

Advocates for Highway and Auto Safety agreed with DOT’s contention that data does not support liberalizing truck size and weight.

“This is another critical reason why the House and Senate should reject any truck industry proposals to change truck size and weight limits,” said the group’s president Jackie Gillan. "Right now the House is poised to vote on H.R. 2577, the annual spending bill for the U.S. Department of Transportation, which contains numerous anti-truck safety riders. None of these measures has been subject to any congressional hearing, government review or public input, yet all of these measures are certain to result in more truck crashes, deaths and injuries. For example, H.R. 2577 will overturn state laws and force families across the country to share the road with bigger, longer, heavier and more dangerous trucks pulling double 33 ft. trailers.” 

“The technical reports of the Department of Transportation’s Comprehensive Truck Size and Weight Study have confirmed our concerns with the study,” said Jennifer Tierney, Board Member of Citizens for Reliable and Safe Highways, and member of the Motor Carrier Safety Advisory Committee.

“It is encouraging to know that the DOT did not cave in to industry pressure and are recognizing that the safety of the American public should not be put in jeopardy based on incomplete data," she continued. "When the DOT conducts further research and has more data on truck size and weight, I know they will see what everyone in the safety community has long been saying, longer and heavier trucks will result in more crashes, more deaths, and more injuries.”

That’s just a sampling of the widespread and entrenched opposition to liberalizing truck size and weight laws, meaning reform proponents will continue to face an uphill battle on Capitol Hill.  

As for that specific effort to legislate twin 33 trailers via a rider to the T-HUD bill, President Obama has already threatened to veto that legislation.