How Do They Build Bridges Over Water?

Bridges are essential for traveling to many places. However, it takes a lot to build a bridge, especially if it needs to go over water.

If you live around water, you may wonder how people build bridges accordingly. Consider how it works so that you can share a fun fact with your friends and family.

How Do You Build a Bridge Over Water?

You have to use cofferdams in the water, or you can lower caissons into the water. That helps create a platform or dam. Construction workers will then build towers over the dams to help support the bridge.

The crew will use equipment like hydro platforms or floating cranes. That will make it easier to assemble the bridge and put everything in place.

Ways to Build a Bridge Over Water

Construction workers can choose from a few methods to build a bridge over water. Of course, there’s the easy option for walking paths over small creeks. That method isn’t any different from other bridges meant for walking.

However, when it comes to larger bridges or big bodies of water, you have to do more. Consider the following options for building a bridge over the water.

Normal Bridge

For smaller bridges that you mostly walk on, you don’t need to do anything special. You can construct a bridge that goes across flat or that sits on a curve.

This is a common choice for bridges that go over water in parks or along walking trails. However, it’s not the best option for roads or bridges that will support cars.


When building a bridge over shallow waters, construction crews can rely on pillars. They’ll fill a location to help lay a foundation over the soil. If the soil can’t support a foundation, you can erect a temporary rig on top.

Either way, workers can then set up pillars across the body of water. The pillars can support the bridge, or crews can use mud islands across the stretch of water for support.


For bridges over rivers and seas, builders will frequently use cofferdams. The cofferdam consists of a wall that encloses an area under the water and pushes water out. Inside the dam is where builders will add pillars for the foundation.

Crews have to continuously monitor the water levels to check for high tides. However, this construction method is usually pretty sturdy.

It’s a good choice for long bridges and short ones. But it can take more work to install compared to a smaller bridge.

Case Drilling

A more advanced option is to use case drilling. Using this method, crews will build a water-tight chamber to go under the water. Then, they’ll drill into the chamber and insert a case to create a strong frame.

That allows crews to build a strong bridge over the water. After drilling, they have to make sure the chamber doesn’t let water in so that the bridge will remain stable.

This method works well for longer bridges, and you can build multiple chambers. That way, you’ll have plenty of support over the water.

Why Build Bridges Over Water

Building bridges over water takes a lot of work. It makes sense to wonder why it’s worth it, but there are a few benefits of having bridges go over water.

Consider the following reasons for building bridges across lakes, rivers, and streams.

Get Across

Sometimes, the only way to get from one point to another is to go over the water. This is particularly true when it comes to rivers or even big bays.

You might be able to avoid driving over water, but you’d have to go way out of your way. In other cases, it’s impossible, especially around the Mississippi River, which spans multiple states.

Provide Options

Maybe it’s possible to drive around the water, such as when there’s a small creek. But it could be inconvenient, so a bridge provides options to drivers and pedestrians.

You can still avoid traveling over water if you choose. However, you don’t have to go out of your way, so you can use a more direct route. This is also common in parks with lakes or streams where it’s easy to walk around.

Save Time

Having the option to drive or walk over water can help you save time. Depending on the size of the body of water, driving around it could take significantly longer.

On the other hand, it might only take a few seconds to cross a bridge. You might save a lot of time, especially if you have to cross a lake or river to run errands or go to work.

Walking can also help you save time and get to where you need to go much faster. That way, you don’t have to leave as early to get to work, for example.

Save Money

The time-related benefits can also lead to financial ones. If you’re able to drive over water quickly, you can reduce the amount of gas your car uses. That can then help you save money on car expenses.

Also, you can travel fewer miles than you otherwise would. Your car can then go longer between maintenance appointments since you don’t drive it as far.

How Do Crews Build Bridges to Go Over Water?

Crews can use a few methods to build bridges over the water. For small bridges, they don’t need to add any special support mechanisms. However, they may use pillars or cofferdams to create more secure bridges, usually for larger bridges that will support vehicles.