We need to fix things we can't see or feel while driving.

When citizens and government officials talk about roads in South Dakota, they usually discuss potholes, other surface problems, widths, turn lanes and many other things we can see and feel while driving. But it's below the surface that needs our attention and money now. That means bridges.

When the topic of bridges is brought up to a city person, they might think of substantial bridges that span a river or bay. They may be huge in size but few in number.

In rural areas, the opposite is true: We have a lot of modestly small bridges, some as simple as culverts under a gravel road. The modest size doesn't always mean modest in cost. They still need to be designed to handle very heavy vehicles, such as semis hauling farm products.

A recent study by a transportation research group known as TRIP showed South Dakota's rural bridges are in worse condition than most other states. The study concluded 18% of the state's rural bridges are structurally deficient, fourth worst in the nation, behind Rhode Island, Oklahoma and Hawaii. By contrast, our road surfaces are ranked better than the nation as a whole.

When roads were first platted more than a century ago, the idea was to have a road every mile, both east/west and north/south.

The railroads stopped every few miles. That would allow horse-drawn wagons to efficiently get commodities to depots. Driving over creeks required very modest bridges, often made of wood.

As farm vehicles replaced horses, the size and weights of the loads grew. Bridges were replaced with stronger structures, often concrete, but still modestly sized.

Today's farmers now haul tremendous weights over rural roads to get to an elevator, livestock barn or ethanol plant. The small rural bridges just aren't up to the task. And the problem was worsened in Lake County during the heavy September 2019 rains, which washed out some culverts in rural areas and may have weakened larger structures.

Bridge repair or replacement can be expensive. The South Dakota Department of Transportation provides grants through a program called Bridge Improvement Grants (BIG), but they are difficult to get. There are far more applications than money.

There is no magic solution to the bridge repair/replacement problem. Perhaps the most important act is to observe weight limits, as excessive weight damages bridges and shortens their useful life. There may be a small number of low-traffic roads with deficient bridges that could be closed.

After that, we'll just have to keep plugging away to make progress on bridge quality over time.

-- Jon M. Hunter