Corrugated Metal Culvert Applicate in Drainage Culvert Under Highway

What should we consider how to choose a corrugated steel culvert to be culverts for our highway projection.

Firstly, we have to confirm the diameter of the culvert. The diameter of culvert is as per the rate of flow of the flood. The corrugated steel culvert is round shape, we need to condier the roughness of the culvert, because our culvert is corrugated steel structure, the difference corrugation size with difference roughness. In fact, the roughness almost can be ignore, because there is no affect to the flow rate of flood. After so many years application, we find that the corrugated steel pipe culvert has less sedimentary material than concrete culvert.

Secondly, we have to make sure the corrugation size and thickness of the corrugated metal culvert. This is according to the live load and dead load on the top of the culvert. The live load means the vehicles which will pass on the top of culvert. Normally for the high way projection, the live load is easy to calculate, because therer is a weight limit on the highway. The heaviest live load is only the heavy type truck. The dead load means the filling back height. This is big difference, some projection with a small filling back height, under this condition, the live load is an important factor we have to consider, because the live load will be a big affection to the corrugated metal culvert. Then we have to get all details of the live load, for example, how many axles the truck has and what is its maximum weight. Some projections with a big filling back height. It even several tens of meters. Then we only consider the dead load is OK, the live load can be ignore.

Thirdly, we have to consider the environmental factor, is there strong acidic or alkaline environment. Because our corrugated metal culvert is made by steel, anti-corrossion is essential. Normally, we adopt hot dip galvanization. It can meet the anti corrossion request in most environment. And its design working life is 50-70 years. But if near beach, or some place with high acidic, then only hot-dip galvanization can not meet the design working life, maybe only 20-30 years. Then we have to consider other anti corrosion method. We adopt painting asphalt on the surface of the zinc coating offenly, then it is no problem, in some extreme environment, we also can adopt hot-dip plastic. It is expensive, but it has a strong anti corrusion performance.