As lawmakers continue to struggle over how to fund the state’s transportation budget, drivers are contending with bridges that have deteriorated to their worst condition since 2003, according to Federal Highway Administration data.
While the number of structurally deficient bridges has held relatively steady over the past decade, the average structural fitness of the state’s bridges has been declining since 2008. The National Bridge Inventory rates the structural fitness of a bridge from 0 to 9, with 0 indicating the bridge is closed and 9 indicating its status is superior to desirable criteria. Since 1992, about a quarter of Wisconsin bridges were rated an 8 or 9, the best two designations on the evaluation scale, peaking at around 27 percent from 2006 to 2008. By 2016, that number had fallen to 19 percent, the lowest in the span of the data.
The percentage of bridges that are “basically intolerable” meanwhile increased slightly from 2.5 percent in 2008 to 3 percent in 2015 and 2016. That slight increase on the low end only accounts for about 100 of the state’s 14,230 bridges. But combined with a general slide in ratings, the average bridge rating has decreased from a high of 6.5 in 2008 to 6.3 in 2016, the lowest since 2003.
For the most part, Wisconsin’s bridges are converging in the middle range, creating the potential to significantly swell the number of bridges in poor condition in coming years, requiring more of them to close or impose weight limits.
The main concern with the deteriorating condition of bridges isn’t safety — it’s commerce. Bridges are inspected regularly, and those in very poor condition are posted with weight limits or closed as needed. Those closures and weight limits can have a significant impact on agriculture, timber and other commerce that involves transporting heavy loads.
The number of bridges posted with weight limits has already more than doubled since the mid-2000s, hitting a high of 875, or 6 percent of bridges, in 2015 and 2016. County Highway Administration Executive Director Dan Fedderly said that’s both due to declining bridge conditions and recent increases in the amount of weight trucks are allowed to carry. Some bridges end up posted simply because they weren’t designed to carry that much weight.