Agricultural loads are destroying rural roads, bridges

The bridge carrying Postel Avenue, a gravel-surfaced road north of Quasqueton, has a posted maximum load of 12 tons on two axles or 23 tons for a truck towing a two-axle trailer.

County Engineer Brian Keierleber knows that limit is treated as a suggestion, not a legal standard.

“If you can fit it on the bridge and it didn't fall down yesterday, they'll try and run across it,” Keierleber said, pointing to shattered timber pilings. “Now imagine a school bus going over that.”

Keierleber and his colleagues across Eastern Iowa are patching up roads and bridges only slightly removed from the horse-and-buggy era as they buckle under bigger, heavier agricultural equipment.

“We're dealing with an infrastructure, most of it coming from the early 1900s, and it's not keeping up with the changes in agriculture,” Keierleber said.

Keierleber said a loaded 750-bushel grain wagon weighs nearly 100,000 pounds, not counting the weight of the tractor pulling it. He estimates a loaded 10,000-gallon liquid manure tanker weighs about 140,000 pounds. At least one manufacturer markets a 2,000-bushel grain wagon weighing 32,700 pounds empty, or about 150,000 pounds loaded - again not counting the tractor.

Those kinds of loads are pushing county roads and bridges beyond their limits. Keierleber ordered the Postel Avenue bridge taken out of service Oct. 10 - one of three county spans closed in a two-week period this harvest season. School buses and nearby residents are now sent miles out of their way.

“We have the same stress,” said Linn County Engineer Steve Gannon. “Vehicles for farming get bigger. Farmers no longer confine their operation to an internal movement (between fields). There's an awful lot more loading and hauling with tractor-trailer rigs.”

Steve DeVries, director of the Iowa County Engineers Association's service bureau, said funding can't keep pace with conventional traffic, let alone agriculture. “What agriculture needs is way ahead of what we've got,” he said.

Washington County Engineer David Patterson warned in a September 2008 report to county supervisors that gravel roads were being damaged faster than they could be repaired.

“Conditions have continued to head in that direction,” Patterson said last week.

Patterson said hog-confinement operations generate dozens of tractor-trailer trips to deliver grain and to take stock to market. He counted 942 confinement buildings in Washington County two years ago, with dozens built since.

Responsible for about 1,000 miles of road and 257 bridges, Keierleber figures his $288,000 annual bridge fund can pay for the replacement of one bridge a year using conventional construction methods.

“And a 257-year-old bridge isn't a good bridge,” he said.

So Keierleber and other engineers are innovators, early adopters of the latest cost-reducing techniques. On the sleety, windy day before Thanksgiving, he showed off a new bridge using a woven fabric material instead of steel in its support structure, saving half to two-thirds the cost of conventional construction.

A favorite low-tech route to a less-expensive bridge is to recycle old railroad flat cars, costing about $12,500 each. Keierleber took a visitor to a span constructed of two 89-foot railroad flats laid side-by-side atop concrete abutments on each end and a single concrete piling.

The span cost about $45,000, including labor, compared with about $200,000 for a new concrete deck. Rebuilding to the latest federal standard would have required a higher deck and other improvements, bringing the cost to about $400,000, Keierleber said.

“But it gets the people across,” he said of the improvised replacement.

Keierleber's crews also string cables across the tops of some aging bridges, creating an 8-foot clearance that blocks large trucks or tractors and combines from crossing.

“When the neighbors realize it's a matter of having the cables or not having a bridge, they'll work with you,” he said. “It takes cooperation within the community.”

A long-term solution comes down simply to money. The state Legislature made an attempt in 2008, passing TIME-21 legislation that increased the annual registration fee on pickups to raise an additional $165 million for roads and bridges.

“But it gives us a smaller percentage of the funds,” Keierleber said.

Support may be building toward an increase in the state's 21-cents-a-gallon gas tax, unchanged since 1989.

The agricultural industry is noting the deterioration of rural roads, said Chris Lang, president of the Iowa Farm Bureau. He estimated counties were $200 million short of their road maintenance needs in 2008, “and that was before the floods.”

“Iowa needs to look at a fuel tax increase,” Lang said. “That would certainly address at least part of the problem.”

Lang said governor-elect Terry Branstad “has his hands full,” and he doubts a gas tax increase stands a chance when the Legislature convenes in January. He hopes instead for action in the 2012 session.

“If it's (an increase of) 8 cents, we need to get to that and dedicate it for infrastructure,” he said. “If it becomes a dime, there's the knowledge that dime is only used for roads and bridges.”

Such an increase wouldn't hit farmers directly; fuel for construction and farm equipment isn't taxed.

In the meantime, the Farm Bureau urges farmers not to fill high-capacity wagons and trucks to their maximum load, Lang said.

“It costs more time and effort, but you need to set good examples in those cases,” he said.

Keierleber will continue to buy retired railroad flat cars to make into bridges.

“We're on an unsustainable course is really the reality,” he said.