What Makes a Road Drainage System? Here Are 3 Important Components

Posted on Jun 20 2018 - 3:28pm by Admin

Road drainage hatchA road drainage system helps to control the water on a road and its surroundings. Generally, the system contains a dewatering part and the drainage. In this case, ‘dewatering’ refers to removing the surface water from the road while drainage aims at keeping the way dry.

Civil engineering firms in New Orleans generally score drainage systems by the ‘weakest link.’ That is to say that if any element of the system is out of whack, the whole system is flawed and the road is likely to be damaged.

The other side of the coin is that if the system is well built and maintained, it is sustainable as an investment policy. The following are three critical components of a road drainage system:

The Pavement

Also called the wearing course, the pavement forms the top layer of the road. It provides waterproof features, protecting the inner structure of the road. As a rule, roadways have to be impermeable, with no cracks.

They must also have enough cross fall to lead water off the road surface. The recommended cross fall varies by the type of road, but there is a range of 3%–5% for straight roads made of asphalt or gravel.

Side Ditches

Water off the surface of the road collects in the side ditches. The only time when side ditches are not necessary is when the road is on a high embankment. The gradient of a side ditch should be a minimum of 4mm/m. The guidelines for the depth of the side ditch vary by country and location.

Outlet Ditches

Outlet ditches lead water away from the side ditch, discharging into lakes, river channels or other waterway systems. If the outlet ditch has a clog, for example, it traces back to rainwater on the surface of the road.

The outlet ditch is typically located outside the road area, and so the engineer must gain permissions from landowners during construction and repair.

A good drainage system works to remove rainwater from the surface of the road. More to that, it keeps the way dry and maintains roads’ bearing capacity. Consequently, the road is  safe to drive on.