Which one is better, single-cell box culvert and double-cell box culvert?

The use of double-cell box culverts is preferred to single-cell box culverts for cross-sectional area larger than about 5m²
owing to the following reasons:

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

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

(iii) The provision of temporary flow diversion can be easily provided for inspection and maintenance of each cell. During routine maintenance operation, water flow can be diverted to one cell and the other one is open for desilting.

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

This question is taken from book named – A Self Learning Manual – Mastering Different Fields of Civil Engineering Works (VC-Q-A-Method) by Vincent T. H. CHU.