Looking for Solutions to the High Cost of Replacing Bridges

It is no secret that bridges are one of the biggest problems facing our infrastructure budgets, not just in the Midwest, but throughout America. As gas tax and other funding mechanisms cannot keep up with the rapidly increasing costs of replacing bridges, the problems are getting worse. With no relief in sight, local communities and counties have to start thinking of ways to tackle the issue that are outside the typical approaches.

What are Structurally Deficient Bridges?

Bridges vary in levels of deterioration. But the simplest way to differentiate the bridges that are in the most need of replacement is point to the bridges that are “structurally deficient” as per a standard bridge rating system.

As defined by the Iowa DOT structurally deficient bridges are:

Bridges that have deteriorations, cracks, or other flaws that reduce their load carrying capacity which may cause weight restrictions on the bridge. Most structurally deficient bridges can continue to serve traffic safely if they are properly inspected and maintained.

How Big is the Problem in the Midwest?

The American Road and Transportation Builders Association compiled a table out of 2023 Federal Highway Administration (FHWA) National Bridge Inventory (NBI) data that depicts the bridge problem we have in the United States. Provided below is an excerpt from that table, concentrating on the Midwestern states:

As shown above, Iowa sits at the top of the pile for the overall number of structurally deficient bridges. But it’s an issue that’s not constrained to Iowa. Ten of the 12 Midwest states rank in the top 20 in number of structurally deficient bridges. Funding bridge repair and replacement is a significant issue for the Midwest. Regardless of how many of each state’s bridges are in poor condition. Midwest states occupy 10 of the top 25 states in overall number of bridges, including five of the top seven. The other two in that top seven? Texas and California, two of the three largest states in the union by area.

Trying to maintain and replace a disproportionate share of bridges than a majority of other states puts a heavy toll on state, county, and municipal budgets.

Old Downey Street Bridge, by NPS Photo; Wikimedia

Trying Something New

Rural counties and communities are trying several innovative solutions to the predicament. Some of the different techniques that rural governments are using to reduce costs on bridge replacement include Buried Soil Structures, Galvanized H-Piling and/or Beams, Precast Inverted Tee Slab Span Bridges, and Prestressed Precast Double Tees.

Some governments are trying to repair these structures before they deteriorate too much, utilizing techniques like Penetrating Concrete Sealers, Thin Polymer Concrete Overlays, Piling Encasements, and Bridge Deck Overlays.

Yet other counties and communities are making the tough decision to conduct a road diet. Unfortunately, not the popular type of road diet that improves safety and walkability. Governments are having to consider permanently closing sections of roads rather than replacing the bridge. It’s a viable solution if a sufficient alternate path exists without hampering emergency services. But it’s not typically a solution that wins votes.

Pre-Fabricating a Possible Solution

But there’s another solution that counties and communities have been looking at more and more. During my time working for a council of governments in southern Iowa a few of the County Engineers that I worked with were taking a long look at their problem bridges. Many of the bridges they were replacing were overbuilt in relation to the drainageway they were spanning. Using the knowledge and resources that they have now, the engineers concluded that they could replace their dilapidated bridges with culverts. It’s a solution that provides a long-term solution at a fraction of the price of a new bridge. These cost-effective replacements were designed to withstand a 100-year flood but also offered lower long-term maintenance costs.

One innovation that has made the bridge-to-culvert transition even more enticing has been the development of the prefabricated box culvert. Prefabricated box culverts are typically constructed in a controlled environment and installed, rather than a cast-in-place solution. This method typically reduces the cost even more, while limiting the time that the roadway is closed.

One company, Contech Engineered Solutions, is even making these culverts out of aluminum. It is yet another affordable solution that has been used in several counties with low-volume roads.

Something has to Give

City and county budgets keep getting tighter and construction costs keep spiraling up. Government entities need to keep looking for innovative ways to approach the issue of structurally deficient bridges.