Restricted bridge list on the rise in county
WORTHINGTON -- By early spring, 13 more bridges in Nobles County will be posted for restricted weights, bringing the total number of bridge postings in the county to 27.
While that may sound like a lot, Public Works Director Stephen Schnieder said it is little more than 7 percent of the county's 365 bridges on the township, county road and county state aid highway system.
"That's not bad," he said. "They're not all supposed to be in perfect condition at the same time. Percentage-wise, we're doing OK."
Most of the bridges with restricted postings are in western Nobles County, along the Kanaranzi Creek and the Little Rock River, as well as in the northeast area of the county, in Hersey and Graham Lakes townships. Schnieder said 13 of the bridges are or will be posted to restrict travel by special hauling units -- straight trucks with multiple axles, including many feed delivery, milk hauling and gravel trucks -- while the remaining 14 bridges have a combination of weight restrictions, whether it be for a straight truck, special hauling unit, a semi tractor-trailer and/or a truck and trailer.
A majority of the restricted bridges are timber bridges, Schnieder said, adding that there are also some steel truss bridges and old, cast-in-place concrete bridges on the restricted list.
At this point, 23 of the 27 restricted bridges are eligible for funding. Nine of them are on the township road system, with the remaining 14 on the county highway system.
"The reason some of these aren't eligible for replacement is they look at the overall condition of the bridge," Schnieder explained. "Some of these bridges are posted for 36 tons (maximum) ... and the typical tandem axle truck weighs 28 tons.
"Because the bridge is in good shape, we're not going to replace it. Most trucks can still use it," he added. "These special hauling units are the only ones who can't use it. That, in itself, does not warrant replacing the bridge at this point."
Special hauling units have become more prevalent on rural roads in recent years, following a change in state law that allowed for tandem axles at the rear of straight trucks. Schnieder said two axles were permitted, then three axles, and now, some extended straight trucks can have six or seven axles underneath. Those concentrated multiple axles are just too heavy for some of the older bridges to bear.
Bridges that restrict the special hauling units don't always have the same restrictions for semi tractor-trailers. That's because the axles on a tractor-trailer aren't as concentrated. By the time a semi's rear axles reach the bridge, the front axles are already off of the bridge.
Implements of husbandry such as livestock trailers, which have always been exempt from weight limits on the road surface, are subject to weight limits on a bridge.
While bridge postings are meant to keep oversized loads off the structures, Schnieder realizes that not everyone follows the law.
"Most people do the right thing, but we do have a small percentage of people who don't follow the laws," he said. "If someone goes across a posted bridge, they can be fined."
There's also a "relative evidence law" that enables law enforcement to pull weight tickets at grain facilities to see how heavy the loads are that are traversing the county's road and bridge system. Weight receipts showing the vehicle had an overweight load can still lead to a fine, Schnieder said.
The weight restrictions are in place not to make it difficult for truckers to get from Point A to Point B. It comes down to safety.
"If you go across the bridge and it gets damaged or collapses while you're there, you are responsible for the costs of replacing that bridge," Schnieder said. "You created the failure by breaking the law. The consequences of your actions could be quite expensive."
While Schnieder compiles the list of restricted bridges, Nobles County commissioners are typically involved in the prioritization process. Typically, the bridges are slated for replacement over a four-year period.
"We do the township bridges as we have time --township bridges are a lower priority than the bridges on our own road system," he said. "We try to do bridges that restrict the use of the roadway."
The more restrictions a bridge has placed on it, the higher the priority is to get it replaced. Heavier traveled roads with restricted bridges also get moved up on the list; and Schnieder said the hardship created by the detour route is also examined.
Some bridges also get slated for replacement in a particular construction season because there is other work being done in the neighborhood. For instance, a bridge south of Dundee on CSAH 18 will be replaced in 2015 because the county will be working on the roadway that summer.
In the past, the county didn't have a prioritizing system for bridge replacement -- they simply took care of them as they became restricted. In recent years, however, a backlog of restricted bridges has developed.
"There's so many of them, it will take us four or five years to get them all completed," Schnieder said.
Township boards decide the scheduling of bridge replacements oftentimes on the availability of funding. While the actual cost to replace a township bridge structure is covered by grant dollars, the township is still responsible for removal of the old bridge, design costs and for putting gravel in after the new structure is in place. Those expenses can range from $5,000 to $10,000 for a township -- a significant expense when some townships only have $50,000 to $70,000 to maintain their roads over the course of a year.
Available financing is also a concern for bridges on the county road system.
"If the funding is there, we would hope to do the majority of these bridges over the next four or five years," Schnieder said.
The average cost to replace a bridge in Nobles County, whether it's on a township road or a county state aid highway, is approximately $80,000 to $100,000, Schnieder said. Some bridges will cost $20,000, and others will cost $300,000.
State bonding money is primarily used for bridge replacement on the county road system. While that covers 100 percent of the replacement costs, Schnieder said the county is responsible for the design, removal of the old bridge and resurfacing costs.
On the county state aid highway, the county receives just 50 to 60 percent of the funds for bridge replacement.
"The remainder has to come out of our CSAH allotment we get each year," Schnieder said. "We have to be careful, too, on how much we can do in one year. We have 14 bridges we can do, but we can't afford to do a lot of them in one year because we have other projects we have to do.
"If the bridges are real bad, they may qualify for funding from the federal transportation fund," Schnieder said.
The expected lifespan of a timber bridge is approximately 70 years, while precast concrete culverts have a 100-year lifespan. In Nobles County, many of the timber structures are being replaced by the concrete culverts, not just because they last longer, but because they are less expensive.
"They are cheaper to design, they do not take as long to install and the overall construction costs are less," Schnieder explained. "Instead of taking three months to build a bridge, we can construct a culvert in two weeks, so there's much less disruption to the public of having the bridge closed while the culvert is being replaced."
Schnieder said several of the bridges that now have weight restrictions placed on them were built in the 1950s, '60s and '70s.
Most bridge replacements in the county are done after Sept. 1, and that's because of the presence of endangered species like the nesting swallow and the Topeka Shiner. The swallows often nest under bridge structures, and once they are nesting, construction crews have to wait until after Sept. 1 to do work on the bridge. The Topeka Shiner, found in western Nobles County, can't be disturbed until after Aug. 15.
Daily Globe Reporter
Julie Buntjer may be reached at 376-7330.