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Do bridges require drains? This is probably a question you’ve never thought of, but yes, bridges do require drains. Bridge drainage is essential in maintaining the health of the bridge. Improper drainage can lead to erosion, harming the structural integrity of the bridge. In extreme cases with enough water damage, this could even cause the bridge to collapse. This is why having and maintaining proper drainage is so crucial. Having proper drainage installed in a bridge will ensure that excess water is disposed of properly, preventing these issues.
When you look at the typical infrastructure of a bridge it becomes clear pretty quickly why they would need drains built into them. If a bridge is in an area that receives a very heavy rainfall, without drains to get rid of the excess water the rainwater would just pool on the bridge. This pooling causes numerous issues, such as pedestrians having issues crossing the bridge, cars having issues crossing or getting damaged, and in worst case scenarios, cars hydroplaning which could cause injury or even death.
To ensure that these drains are effective, bridge drains are installed at specific intervals along the curb or gutter line. These drains are then either connected to pipes which lead to a point of disposal such as a local sewer system (called class 1 drainage), or are designed so the water can simply free fall to the ground below depending on where the bridge is located (known as Class 2 drainage.)
A great example of a free fall or class 2 drainage style bridge is the Brooklyn Bridge. The Brooklyn Bridge is designed with slopes on each side of the bridge which causes the water to flow to the edges of the roadway. Then, the water simply runs off the sides of the bridge and drains directly into the East River. This is particularly useful for New York as their sewer system is so massive and used so often that draining directly into it would cause a lot more unnecessary and potentially harmful strain on their sewer system.
On the other hand, an example of a class 1 drainage style bridge is the Fort Garry Bridge. Instead of using a free fall system, this bridge is designed with a sewer interceptor pipe that takes excess water, drains it into the local sewer system and transports it to the sewage treatment plant. This system prevents the bridge from draining into the local freshwater river. Both of these drainage systems are equally effective, so choosing between the two comes down to factors such as existing infrastructure, cost and preference.
One thing to note is that class 2 drainage systems have come under some scrutiny due to potential negative environmental impacts. Rainwater runoff can sometimes contain contaminants such as gasoline, oil, and road salts. These contaminants can harm local aquatic populations when the water is drained directly into a body of water, so it is important to remain mindful of these concerns when choosing your drainage system.
It should be noted that having the right drainage system is only half of the job. If the drains are not properly maintained, it won’t matter what system you use. Bridge drains can easily get clogged by debris such as leaves, road sediment, and trash. If this debris is not regularly cleared out, problems mentioned earlier such as erosion, hydroplaning, and injury can occur. Cleaning these drains can be as simple as removing debris with specialized cleaning tools or using a pressure washer. For bigger clogging issues, special equipment such as vacuum trucks can be used to remove blockages from the drainage system. It is important to remember that taking care of your drains is just as important as installing them.
One of the best options for a drainage system that is both durable and easy to clean is the Slot Drain system.
Slot Drains were installed on a roadway in the 16th Street Mall project in Denver, this is an example of load class F rated slot drains that could be deployed on a bridge to withstand constant flows of heavy traffic.
The Redmond Technology Station Bridge that connects Microsoft’s east and west campuses is an example of a radius slot drain suitable for pedestrian and bike traffic deployed on a bridge.
These drains not only worked to handle traffic and drainage, but also blended seamlessly with the spectacular designs of the bridge and sidewalk, making them an ideal fit.
To learn more about how Slot Drain Systems can be part of your next infrastructure project, reach out to one of our Territory Sales Representatives today.
