Q. Diffrence between Single and double-cell box culvert?

The usage of double-cell box culverts is preferred to single-cell box culverts for cross-sectional area larger than about 5m²because of the below reasons:

(i)  Where there is tight headroom requirement, use of double-cell box culvert can shorten the height of culverts by having a wider base so that same design flow can be accommodated.

(ii) Invert of one cell can be designed at a lower level to cater for low flow condition so that it decreases the occurrence of sediment deposition and stop the presence of standing waters.

(iii)Provision of temporary flow diversion can be easily provided for maintenance and inspection of every cell. At the time of routine maintenance operation, water flow can be diverted to one cell and other one is open for desilting.

If a choice has to be made between a single-cell box culverts and smaller multiple pipes, it's better to select single-cell box culvert due to the lower risk of blockage when compared with smaller size of multiple pipes. Additionally hydraulic performance of a single-cell box culvert is better than multiple pipes system due to the larger hydraulic radius associated with the box culvert for a given cross-sectional area.