Madison County, Iowa, is known for its old-timey bridges, but as it turns out, the rest of Iowa has an abundance of old, rickety bridges as well.

According to a recent report from Transportation for America, Iowa has the third-highest rate of structural deficiency among its bridges in the United States. More than 5,000 of the state’s 24,465 bridges — nearly 21 percent — are deficient. The average daily traffic over Iowa’s deficient bridges is approximately 1.7 million automobiles.

Some of the state’s at-risk bridges are right here in Iowa City. The Johnson Street and Lucas Street bridges that span Ralston Creek are both deficient, as is the Burlington Street bridge over the Iowa River, which is nearly 100 years old.

The Iowa Department of Transportation notes that a structurally deficient bridge is not necessarily an unsafe bridge. A bridge is considered structurally deficient when “load carrying elements are found to be in poor condition due to deterioration” or when it causes intolerable traffic interruptions on the waterway it spans.

Structurally deficient bridges typically require significant maintenance or repair or, in some cases, major rehabilitation and replacement to address the problems.

In addition to Iowa’s structurally deficient bridges, the American Society of Civil Engineers reports that the state also has almost 1,300 functionally obsolete bridges — bridges that were built to not built to current required specifications.

Though the state’s bridges may not yet be a major safety concern, an aging infrastructure will eventually become dangerous if the current concerns are not promptly addressed.

The state government has already taken some steps toward fixing this problems — 249 deficient bridges have been fixed since 2011— but should act to rehabilitate the rest of Iowa’s bridges sooner rather than later.

The danger of inaction with regard to aging bridges is demonstrated by the catastrophic bridge failures of the past few years. In May, a bridge on I-5 spanning the Skagit River in Washington that was rated functionally obsolete collapsed. In 2007, an I-35 bridge over the Mississippi River collapsed during rush hour, killing 13 people.

There is already some action in place in Iowa. According to the Iowa Department of Transportations’s five-year infrastructure plan, the state spent about $20 million on repairs to more than 4,000 of the state’s bridges in fiscal 2013.

But over the past few years, funding for infrastructure projects in Iowa has fallen sharply. In fiscal 2010, state infrastructure funding totaled nearly $500 million. By fiscal 2013, that number had fallen by more than half to roughly $200 million.

Iowa’s infrastructure funding has fallen despite an abundance of persistent problems with its bridges, roads, and dams. This funding trend should be reversed.

The government exists, at least in part, to provide the public goods necessary for the development of the economy and society more broadly. A functional infrastructure is a crucial public good.

A key component of Iowa’s infrastructure, its bridges, has more or less been left to decay. In some ways, this trend is an unfortunate product of politics. After all, building a new bridge is a relatively sexy and politically valuable proposition. Repairing a bridge, however, is considerably less exciting.

Lack of excitement aside, Iowa must act to fix its deficient bridges now before they become a risk to public safety.