The weighting game

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Absent increased infrastructure investment, dwindling funds could result in more load-posted bridges.

In the aftermath of the I-35W bridge collapse in Minneapolis, states went diligently to work inspecting bridges of similar design, while the news media obsessed over terms like “structurally deficient” and “functionally obsolete,” classification phrases for bridges with significant wear or outdated design. Lost in the furor was an item of great concern to the industry – the push for higher productivity on already congested highways.

Combined with the upswing in bridge inspections, Ted Scott, a special projects leader for the American Trucking Associations, says he expects to see more of a particular trucker nuisance in the months ahead: load-posted bridges. “Neither structurally deficient nor functionally obsolete bridges matter much to trucking companies,” Scott says.

But load-posted bridges, which have weight restrictions in the interest of safety, require routing around or lighter loaded truck weight, which puts a damper on productivity. “Luckily,” Scott says, currently “there are only 760 [National Highway System] bridges that are posted.” Moreover, nearly a third of that number is from Missouri alone, which has specially designated “commercial zones,” where some NHS bridges fall under state per-axle limits rather than total weight regulations and require postings of weight limits far heavier than normally would be required.

According to 2006 Federal Highway Administration data, there are 115,051 bridges on the National Highway System. Subtracting the majority of the posted Missouri bridges, a mere 600 or so load-posted bridges represent just 0.5 percent of total bridges.

That number could also climb if shippers and carriers follow through on a move, endorsed by leading energy and military figures, to raise the federal legal weight limit of trucks on the highway system from 80,000 to 97,000 pounds with the addition of a third trailer axle.

Darrin Roth, highways director for the ATA, says the organization will be actively pursuing change in the law on this count in years to come. “Current law already allows states to authorize heavier trucks off the interstates,” he says. “We believe that with careful bridge management, [the 97,000-pound truck] can reduce overall infrastructure and shipping costs.”

Still, proponents admit there is a drawback to the proposal. Jake Jacoby, head of Americans for Secure and Efficient Transportation, a lobby dedicated to increasing truck weight, stresses that with the addition of a third axle, the per-axle weight on highways will actually be less, reducing overall infrastructure stress. But “the one negative is bridge wear,” he says.

ATA notes overstress and long-term fatigue are the major factors in bridge deterioration. Roth characterizes overstress as “the possibility of severe damage and possible collapse caused by a single extreme loading event” – in other words, too much weight on the bridge at one time – while fatigue is the cumulative damage caused by millions of vehicles over time.

“The vast majority of interstate bridges were built to handle weights well in excess of 97,000 pounds,” says Roth, “and many off-system bridges were built to similar standards.” In the event of any weight increase, he adds, “any bridges for which there is any doubt should be inspected to ensure that they can safely handle the added weight.”

And if they can’t, the signs come out.

Cincinnati recently posted the urban Eighth Street Viaduct over Mill Creek and CSX rail facilities with a 20-ton limit, rerouting to River Road and other alternates many of the estimated 1,400 trucks a day that formerly passed across its 79 concrete spans. City Principal Structural Engineer Richard Szekeresh says the posting is the result of normal inspection procedures. “We’ve been watching this bridge deteriorate over time, and it’s actually scheduled to be closed for rebuilding in May.”

These kinds of situations increase the snarl of congestion that plagues the routes through many urban centers, a large trucking concern, ranking No. 4 among issues of importance to those surveyed for the American Transportation Research Institute’s most recent top-10 critical issues report, behind hours of service, fuel and – perhaps you guessed it – the driver shortage.

“[The 97,000-pound truck] will also reduce vehicle miles traveled,” Roth says, “with positive impacts on safety, congestion, fuel consumption and the environment.” Fewer vehicle miles traveled ultimately equals fewer trucks and fewer drivers per ton hauled, a potential threat to driver jobs.

“I don’t think there is any threat to safe, experienced drivers,” says Kentucky-based hazmat hauler Rick Gaskill, adding that heavier trucks might just mean “less newbies of questionable quality coming into the industry.

“I haul in Michigan and Canada quite a bit. [Heavy-haul] trucks are quite common there. They seem to have a better safety record than other trucks mainly because carriers put more experienced drivers in them. While there is a concern about the loss of driver jobs, perhaps [heavier trucks] would just mean less of a driver shortage.”

Todd Spencer, executive vice president of the Owner-Operator Independent Drivers Association, had some sharp words on the issue in May last year, when he said that “shipper interests are largely unconcerned with highway safety or, for that matter, infrastructure.” And he went on to echo Gaskill’s concern about training when he said, “We don’t even train people how to drive the trucks that are permissible now, and we’re going to make the assumption that they’ll be able to drive a truck like this?”

But Gaskill’s also well aware of potential positives – “Heavier trucks will increase the profit margin for carriers,” he says. “It would be nice if part of that additional revenue was passed on to drivers, but I doubt that’s likely.”

Not likely indeed, owner-operator Charles Harrell, leased to Greentree Transportation, concurs. Essentially, he already drives the 97,000-pound truck. In addition to a 1989 Pete 379 he owns a 48-foot spread three-axle Transcraft step deck. With a plate he pays a premium for, he’s legal for heavy-haul freight and gets a better rate for it. If the weight limit goes up and most everybody can do it with the right equipment, he says that better rate will disappear. He says drivers and owner-operators might do well to remember the lessons of the past. “When they went from 73- to 80,000 pounds and 40-foot to 44, what happened?” he says. “I’ll tell you what happened, here we are still making a dollar a mile with four more feet and 7,000 more pounds on the trailer.”

As confident as Roth and others are that these are the trucks of the future, there seems little likelihood that they’ll be coming around any immediate corner in large numbers. All signs point to increased truck weight being a tall order, politically. The I-35W collapse stymies the measure in those terms, more so than it already had been. After the Energy Security Leadership Council, a panel of business and military leaders, including the CEOs of both FedEx and UPS, advocated the measure as a boon to efficiency and security earlier this year (the weight increase showed up in legislation called the SAFE Energy Act, proposed in the Senate Finance Committee and largely based on the ESLC’s recommendations), it was ultimately absent in final energy legislation. Strong opposition from Democratic leaders in Congress’ transport committees, says Jacoby, ensured the absence.

Meanwhile, ASET’s advocating a weight-increase pilot program proposal involving several states. Jacoby’s even recommending a “pay to play” scheme he thinks would solve the bridge-maintenance problem – “a fee [to be paid] by every trailer that adds an additional axle,” he says, which would go into a “designated trust fund used exclusively for bridge repair/enhancements. Having a user fee is acceptable to us as long as it is targeted to the trucks that make this change. This way, if a motor carrier company does not make the retrofits or buy new six-axle truck-trailer combos, they won’t have to pay the fee.”

The House version of the transportation appropriations bill allocates $1 billion from the general fund for bridge maintenance and inspection. Minnesota representative James Oberstar, chair of the infrastructure committee, signed on, but he’d formerly proposed a temporary fuel tax dedicated to bridges as part of his “National Highway System Bridge Reconstruction Initiative.” Those funds would have been exempt from legislative earmarking. Oberstar has publicly backed weight-increase pilot projects of the type Jacoby is recommending in the past.

In light of the last highway reauthorization, maligned from many quarters as “the most earmarked bill in history,” ATA recognizes the benefit of a ban on earmarks, but Roth stresses that increasing funding in this age of skyrocketing fuel and construction prices should be an all-inclusive effort. Bridges are only part of the total highway package.

“Significant segments of the highway system require additional investment,” he says. “We agree with [Oberstar’s] approach of dedicating resources to projects with the greatest need, and his resistance to earmarking.” Now take it further, he says. “This is a model that should be applied to the entire federal highway program.”


The I-10 Twin Spans over Lake Pontchartrain between Slidell and New Orleans, La., have been posted since their emergency repair after Hurricane Katrina at 70,000 and 40,000 pounds on the east- and westbound spans, respectively. A new bridge, a mammoth $800 million, 5.5-mile project, is shown here in early construction phases. Diverted westbound loads into New Orleans typically must circle the lake and run I-55 into the city, adding 59 miles to the trip.

Since Katrina, frequent lane closures on that span, for rigorous inspection and maintenance activities, were the source of many a complaint from motorists, says Lousiana Department of Transportation and Development communications director Mark Lambert, until the necessity of bridge inspection was reinforced in the public mind. “After the Minnesota bridge collapse,” Lambert says, “we did not receive any further complaints about that.”


Trucks’ Part in Collapse Overstated
The mainstream press responded to the Minneapolis I-35W bridge collapse with verve and in some cases valor – from heroic stories of rescue to revealing investigations of the paper trail leading back to longstanding concerns about the bridge’s integrity, press reports moved and provided instruction to us all in how to stay on top of a problem when lives are at stake. But distorted in much of the concern over bridge safety has been the real role big trucks played in that bridge’s wear. None of the leads currently being pursued in the National Transportation Safety Board’s investigation of the collapse involve trucks directly.

“The bridge was not even frequently used by long-haul trucks,” says Clayton Boyce, public affairs vice president for the American Trucking Associations. Truckload carriers typically route around the urban area in other lanes.

The NTSB says to expect an update soon, as this report goes to press, but to date official fingers have pointed to the deterioration of steel gussets in the deck-truss design as well as the additional weight of construction equipment (287 tons’ worth, the equivalent of more than seven fully-loaded tractor-trailers) on the bridge at the time of the collapse.

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