VDOT looking at deck-truss bridges
Story by Chris Graham
A dozen Virginia bridges with the same general type of design as the deck-truss bridge in Minnesota that collapsed last week are going to get a gander from state transportation inspectors – but there’s no reason for alarm.
“What the department is doing is taking the opportunity to do a review of what we’re doing,” said Garrett Moore, the district administrator in the Staunton District office of the Virginia Department of Transportation, in an interview this week on “The Augusta Free Press Show.”
“We put a lot of emphasis on this anyway – but it doesn’t hurt for us to have an outside set of eyes look at what we’re doing. It’s a redundancy that we actually welcome – and we’d like to receive any additional input, because it’s essential to us,” Moore said.
Three of the bridges that will undergo new inspections are located in the Shenandoah Valley – two in Page County and one in neighboring Warren County.
“It just so happened that those three bridges were due for inspection anyway,” VDOT Staunton District engineer John Brock said in an interview on this week’s “Augusta Free Press Show.”
“We had already set up to do these inspections in August – to now find out that central office in Richmond wanted to put these to fresh eyes. So we’re going to let consultants go out and do them – instead of our own group,” Brock said.
All three were built in the 1930s and early 1940s – and are all in line to be replaced by more modern steel-girder, composite-concrete-deck-type bridges.
That VDOT is going with a more modern design isn’t an indication that those in the engineering world think that deck-truss bridges are necessarily a thing of the past.
“This bridge (in Minnesota) was held up by two big trusses – and what that means is if you’re held up by two trusses, and if one of those trusses fails somehow, if one of those trusses has a problem and is unable to carry its load, then all the load goes to the other truss, and it’s going to be imbalanced,” said Kirk Martini, a University of Virginia architecture professor and a licensed engineer.
“I saw one newspaper describe this pretty well – if two people are carrying a piano, and one of them falls down, then the piano is going to fall, but if you have three or four people carrying a piano, and one of them falls down, the other three may still be able to keep it balanced,” Martini said in an interview on “The New Dominion Show” this week.
“But with just two trusses there, there is less redundancy – and the loss of one truss will be a much bigger problem than if you were supporting it with three or four trusses,” Martini said.
The bigger issue, to Martini, involves basic structure maintenance.
“It’s important to remember that infrastructure – the things we need to function normally, running water, electricity, roads, things like that – we tend to take them for granted,” Martini said. “And so instead of bold new initiatives, doing something new, maintaining the infrastructure – which is a pretty boring thing; for a politician, it’s hard to sell maintaining the things that we take for granted as a big campaign issue – and so it’s often something that doesn’t get as much attention.
“The main thing to remember is not to panic because of this – but to keep in mind that when people are talking about infrastructure maintenance, it’s really a critical issue, even though it’s hard to get people’s attention to it,” Martini said.
Chris Graham is the executive editor of The Augusta Free Press.