Mending bridges a constant mission.
Hill is a heavy-bridge maintenance engineer for the Arkansas Highway & Transportation Department, and his crew oversees the inspection of Arkansas' 12,000-plus county, city and state bridges. The bridges range in size from epic constructions spanning rivers to short ones that Hill said are more culvert than bridge.
The National Bridge Inventory rated 861 of Arkansas' bridges as structurally deficient in 2014. The state inspects its bridges at least once every two years--and more frequently for bridges that have earned a structurally deficient label--and Hill insists the term sounds worse than it is.
"We in the bridge community have been arguing about that term for years," Hill said. "It was something they picked up years ago, and once the Feds get hold of something, they're not inclined to change."
Scott Bennett, the director of the AHTD, stressed that structurally deficient does not mean imminent collapse.
"We talked a lot at the national level about the way we describe our bridges, and it makes it sound a lot worse than it really is," Bennett said. "It really just means that there is some structural component that is going to need some attention sooner rather than later. If it's bad enough, we're either going to put a weight restriction on it so it will last longer, or we're going to shut it down. If we leave a bridge open, you'll know that that bridge is safe to travel on."
Bennett recalled a bridge on Interstate 40 was shut down after a truck accident in which the truck caught fire. The fire damaged the bridge, which was closed until repairs could be made.
Hill said a bridge on state Highway 75 in Poinsett County was recently shut down after inspectors noticed a defect that needed immediate correction. Hill said inspectors had wanted to check something out, and when floodwaters receded, they were able to get a better look at a problem area.
Hill said District 10, where the bridge is located, is handling the repair work itself. The heavy-bridge department, which handles statewide inspections, is responsible for the management of the state's large or unique bridges.
Hill said the repair work on the Highway 75 bridge involved driving new piles for the foundation to shore up the bridge's substructure. He said that when a bridge is inspected, inspectors rate the bridge's deck, superstructure and substructure.
In layman's terms, the deck is the roadway on top of the bridge, the superstructure is the support holding up the deck, and the substructure is the foundation. If any of the three rate substandard, the bridge is judged to be structurally deficient.
The designation confusion happens because most structurally deficient bridges in Arkansas are deficient because of the condition of the deck, Hill said. In other words, the driving surface is terrible, but otherwise the bridge is perfectly safe; it's just a rough ride.
"It may just be a really ugly-looking deck, but it makes it structurally deficient," Hill said. "OK, it has a lot of patches, but the bridge is not going to fall down. There's nothing wrong with the bridge structurally; it's just a really bad deck."
Striking a Balance
Hill said the inspection program helps the state keep up with the conditions of bridges. A few years ago, the heavy-bridge department called for repair or replacement of three significant bridges: the Broadway Bridge in Little Rock, the Interstate 30 Arkansas River Bridge and the historic Black River Bridge at Black Rock in Lawrence County.
Demolition and replacement of the Broadway Bridge, a $98.4 million project, is scheduled to begin next year, and the new $39.2 million Black River Bridge opened earlier this year.
But there are thousands of bridges that don't have the high profile or traffic of the major bridges, and the state keeps up with all of them. Hill said there isn't enough money or time to do every repair, so the state follows the metric of doing what is absolutely needed on each bridge before moving to the next.
Or, as Bennett said, "fix it or maintain it in a safe and sound condition until it comes up on a list to replace it."
Most bridge maintenance is handled by the state's 10 Highway Department districts. Hill said the heavy-bridge department, with its experts, is on call to assist with special or complex projects.
"Our budget for bridge replacement is about $90 million, and that is almost what we spent on the Broadway Bridge," Bennett said. "That's one year's worth of our bridge improvement budget on one bridge. That's one of the balances we have to strike. We're still maintaining all those smaller bridges to make sure they're going to last until it comes to a point they need to be replaced."
Bennett said if a bridge develops a problem that needs attention but not to the degree it needs to be shut down for repair or replacement, the state can put a weight restriction on the bridge. That is a stopgap measure to extend the life of the bridge until, as Bennett said, it comes up for replacement.
'Fatigue Starts to Set In'
Hill said many bridges in the state that were built in the 1950s or 1960s are beginning to show their age. Also, Hill said some bridges--which he called "M" bridges--were built as temporary spans that were never meant for long-term use.
"There's not a whole lot of problems with substructure until you get into these M bridges that were built back in the '60s," Hill said. "Those are things we take a little more serious than a deck that needs a patching. With the M bridges, if I had my choice we'd go out and replace every one of them. We don't have the money, so we do what we can to keep them in good shape."
Maintenance is cheaper than repair, which is why the state's inspection crews are constantly on the job. Hill said an inspector can check out three to four culvert-bridges on a good day, but another inspector is scheduled to spend four weeks at the Hernando de Soto Bridge that carries Interstate 40 across the Mississippi River.
"Fatigue really starts to set in," Hill said of the state's older bridges. "We're having to address fatigue cracks more often. It just means more maintenance problems. If you don't address the cracks as soon as you see them, they could be a very serious problem.
"There's never a slack moment. It's how far down on the list can you work on this bridge? It's not very often when we can hit every maintenance need on a bridge, but we can hit the ones that really need to be addressed."
Hill said the state is streamlining its inspection program to make it more efficient with the use of technology such as mobile input to the state inventory database. Hill said Arkansas' use of in-house inspectors rather than relying on outside contractors saves time and money.
By Marty Cook MCook@ABP6.com
Caption: Mike Hill, the heavy-bridge maintenance engineer for the Arkansas Highway & Transportation Department, on the Hernando de Soto Bridge that carries Interstate 40 across the Mississippi River. [SUBMITTED PHOTO]
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|Title Annotation:||SPOTLIGHT: Highway Construction & Infrastructure|
|Comment:||Mending bridges a constant mission.(SPOTLIGHT: Highway Construction & Infrastructure)|
|Date:||Aug 17, 2015|
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