What is a culvert?

Written by LetsBuild

Follow us


Share this story

Lean ebook cover

A culvert is a section next to a road, or a cut in the area underneath it, and its sole purpose is to allow water to drain.  If culverts are not used by roads, water would end up pooling, creating a hazardous problem that people would have a hard time avoiding.  While the true definition of a culvert states that it must be an enclosed tunnel, most people call the ditches next to roads culverts as well.

Most of the time, culverts are constructed when roads are built, but they could be installed later if new water problems arise.

Benefits of a Culvert

As mentioned above, the main benefit of a culvert is that it keeps water from pooling up on the road.  This ensures that the road stays in excellent condition for much longer and there are less potholes.  Plus, drivers will not hydroplane when driving on the road or need to take a detour because there is too much water for them to drive on the road.

The second benefit is that these culverts keep water from pooling up next to the roads and finding its way underneath.  When water gets under a road, it can cause the road to crumble and deteriorate quickly.  The road will start to crumble on the sides and eventually work its way towards the middle until the entire road collapses.

Types of Culverts

There are three different types of culverts that can be installed, and they are:

Box Culverts

A box culvert is the type of culvert that is used the most.  They normally have a concrete base that allows the water to flow through smoothly.  It is often necessary to install these in dry areas, which means that extra steps need to be taken before the installation can begin.

Arch Culverts

The causeway is not disturbed as much by an arch culvert, because it covers the entire width of the drainage area.  Most arch culverts are made from metal, but they can also be made from stone masonry or reinforced concrete.  These culverts are easy to install, and it normally doesn’t take that much time before the work is completed.

Pipe Culverts

Culverts that are installed using pipes are also easy to install and the most common ones are circular pipe culverts.  You must know what factors are in play for the area where the culvert is being installed to make sure that this is the best option.  This is the type of culvert that is used in many urban areas and it is often the top choice for storm sewers.

Bridge Culvert

A bridge culvert is normally found on rivers or canals, but they are also used for road bridges.  This culvert needs a foundation underneath the surface of the ground and there are normally different sections of culverts before the pavement is added on top.

Installing Culverts

There are many things that you must keep in mind before installing a culvert, but these are the ones that you definitely must know:

  • When you go to install a culvert, you must make sure that you are placing it at the right height and grade. Failure to do this will cause erosion problems that will be difficult to repair.
  • You must factor in the cost of maintenance for any of the culverts that you install. The reason for this is if you do not factor in these costs, you may need to close certain culverts for a while until you receive the money or find the time to fix them.  A closed culvert can cause many issues and those issues can cause even more of a challenge when you finally do get to the maintenance that is needed.
  • It is imperative that you are careful when designing the inlet and outlet of any culvert. It is best to miter the ends, so that the water can flow properly.
  • If you want to prevent scouring, you must flare the ends of the outlet section.
  • Erosion can happen inside any culvert and that is why we recommend installing rip-raps or something that works in a similar way.
  • Aggregate materials may be needed during certain installations and it must be applied underneath, to the sides, and sometimes even on top of the culvert. You must choose the proper aggregate for the area you are doing the work in or you may cause more damage than planned.
  • The amount of traffic that drives over a road might mean that the culvert you install needs to have improvements made beforehand. The wrong type of culvert, or a culvert that isn’t installed too deep, will collapse without warning.

Repairing Culverts

While culverts are designed to last for many years, there will come a time when they need to be repaired or replaced.  Regular maintenance can alleviate many of the major repairs that may be needed if you end up ignoring culverts for long periods of time, but even that cannot prevent something major from happening without warning.

Unfortunately, repairing and replacing culverts is very expensive and time-consuming.  Most of the time, the damage includes corrosion, rusty sections, or washed out areas.  While you can try to make minor repairs over time, it is best to simply do everything that you can at one time.

Yes, it will take you a long time to do what you need to, and the costs may be more than you want, but the safety of those going over the culverts should be worth it all.

When you notice that repairs are needed for a culvert, you may want to consider whether a repair will last quite some time or if it is better to simply replace the entire culvert.  While replacing a culvert will take more time initially, it will be less time than if you had to shut the road down multiple times to make one repair after the other.

There are options available that will allow you to repair a culvert without digging it all up and replacing it.  One of them is a lining system that simply goes inside the culvert and makes it work like new again.  It is similar to relining pipes and is supposed to work as well.

It will all come down to your comfort level and how much time you want to spend on each culvert that you work on, because if the relining doesn’t work, you will then need to spend time doing a complete replacement.

Culverts are very tricky to understand, but you must understand that they are necessary to keep areas from getting flooded and becoming dangerous hazards that can injure people without warning.