How safe are our state's bridges?

On the heels of last week's collapse of a bridge along Interstate 5 in Washington, Chronicle science blogger Eric Berger points to a recent American Society of Civil Engineers survey of the state of the nation's bridges and discovers that, of the bridges in the state of Texas, 2.6% are considered "structurally deficient" and 16.6% percent are considered "functionally obsolete."

Due to the size and extent of its road network Texas has about 60 percent more bridges than any other state in the country, making it numerically the most vulnerable to bridge failures. Moreover, one third of the state’s bridges have been in service for more than half a century.

“Bridge maintenance spending must increase to ensure that service life expectations are met for new bridges represented by the increasing inventory level as well as for older bridges,” the engineers say.

To be fair, bridges that are rated "structurally deficient" or "functionally obsolete" are not inherently unsafe. "Structurally deficient" bridges are those that, because of design, damage or fatigue, are restricted as to the type of load they can carry. "Functionally obsolete" bridges were built under codes that are now out of date and were not designed to carry the volume and type of traffic they are now carrying. According to the Texas Department of Transportation, these bridges "do not have adequate lane widths, shoulder widths or vertical clearance to serve current traffic demands."

With that said, you would prefer bridges in your state's inventory not to be "structurally deficient" or "functionally obsolete." "Structurally deficient" bridges might have load restrictions on them that impede freight traffic and hamper local economies. The bridge on I-5 was "functionally obsolete," and it collapsed because a trucker with a high load hit the bridge's structure. Would that bridge have collapsed if it had been built to current clearance standards, rather than ones in effect when it was built in 1955?


The reason why so many Texas bridges fall into these two categories, of course, is simply because there's not enough money to maintain or replace them as they age. This problem is only going to get worse, because even as our transportation infrastructure gets older, we are continually reducing funding for its maintenance and construction. The Washington Post notes that spending on roads and highways has fallen off dramatically since 2008:

How did this happen? States and local governments are the biggest part of the story here. They’ve historically provided the vast majority of spending for roads, highways and bridges, and they’ve been pulling back on spending since 2008 as a result of the economic downturn and requirements to balance their budgets. California’s transportation spending declined by 31 percent from 2007 to 2009, for instance. Texas’s fell by 8 percent.

At the same time, Congress hasn’t filled in the gap. There was a one-time $46 billion infusion of transportation spending in the stimulus bill. But that wasn’t enough to offset the  drop at the state and local level. Meanwhile, the most recent highway bill out of Congress kept federal spending at current levels rather than increasing it.

Part of the problem is the federal (18.4 cents per gallon) and state (38.4 cents per gallon) gas tax. Neither has been raised in two decades, they are not indexed to inflation, and there is no political will for either of them to be raised anytime soon. That means less money from that funding source for transportation every year. Another part of the problem is the lack of a "fix it first" mentality in this country: we continue to want to build new roads even as we neglect the maintenance of what we already have. This, again, is rooted in politics: elected officials like to be able to claim credit for the new highways they've provided for their constituents, and there are no ribbon-cutting ceremonies for routine maintenance.

Fortunately, nobody was killed in last week's I-5 bridge collapse, and a temporary fix for this vital trade route to Canada is in the works. But this incident is just another example about why we need to start having a serious conversation, both at the state and national level, about adequately funding our nation's transportation infrastructure.