Design & Construction of Culverts
The way culverts are laid out may seem so obvious that you never really give them a second thought. As well, they seem to blend in the background because they are so common. Life in this world would be much more complicated if they didn't exist.
As an example, imagine you're designing a new road that connects two points. If the terrain between these points were flat, without obstructions or topographic relief, then it would be nice. This rarely happens, however. Generally, on your journey, you'll encounter hills and valleys, structures, and streams you'll have to negotiate.
In some instances, you can go around some obstacles, but most of the time you'll just have to work with what you have.
Besides having gentle horizontal curves, roadways also require gentle vertical curves, so you may need to detach soil or rock from the high spots and add it to the low spots along the way, also known as cut and fill. But you should be cautious about filling in low spots where water will collect because that's where it will flood.
Culverts are bridges with abutment faces less than or equal to 6 meters in length. A culvert is a permanent drainage structure used to link a road or railway track over a small stream.
Culverts are divided into 4 types, there are: Box Culvert, Pipe Culvert, Open or Slab Culvert, Arch Culvert.
A box culvert is made up of 1-2 rectangular or square openings with their floor and top slabs monolithically manufactured with piers and abutments. These culverts are constructed from RCC precast slabs. Small span box culverts are constructed with stone slabs supported on masonry abutments with brick & stone flooring. Constructing a building can be made more efficient with the use of a box culvert.
Box Culverts with single or double spans of 3 meters or more make sense when there is soft soil and loads need to be spread over a wider foundation area.
Under an embankment of a roadway or railway, 1-2 pipes rest on a concrete base side by side. Steel, RCC & cast iron contains 1-2 pipes held in position over a base of concrete to fix both ends into masonry walls in pipe culvert.
But the accurate diameter & number depends upon the height & discharge of the bank. The pipe gradient should be greater than 1 in 1000. This type of culvert is perfect for a very small stream with less water flow.
Open or Slab Culvert
The culvert constructs of RCC slabs superstructure that can hold a bridge floor are defined as an Open or Slab culvert. The appropriate thickness of RCC slabs gives proper support over piers & abutments that construct any kind of masonry.
The bed of the canal or stream which is sufficiently firm with a maximum span of 3 meters, that is perfect for the open culvert.
The Arch culvert is a unique type of superstructure that has 1-2 arches constructed in any appropriate masonry known as Arch Culvert. Stone-masonry brick masonry or concrete is generally used for constructing arches in this type of culvert.
These types of arch construction are cost-effective & easily constructed. The abutments or piers of these arches are strongly built to carry the load their lateral thrust. Cut-through construction is a perfect fit for arch culverts.
Some waterways are obvious, like rivers and perennial streams, but others are ephemeral, meaning they are active only during wet weather. In the natural landscape, when you fill across low spots, you create impoundments. Your embankment won't keep out water if it can't pass through it. The consequences of this are not just detrimental to the roadway but are extremely dangerous to motorists and other vehicles.
Bridges are one obvious solution: they are the classic way to cross a body of water in a vehicle. Bridges, however, are expensive. A structural engineer must be hired, supported, girders installed, and a road deck installed. Many small creeks and ditches are not suitable for this. Rather than filling in the low spots, we include a pipe that allows the water to drain properly. In reality, culverts are actually quite complex pieces of infrastructure.