79. The diameter of a drainage channel used to divert water from one side of a road to the other must be sufficient to prevent the obstruction of the channel and maintain at all times the free flow of the water. The diameter of the channel may not be less than 300 mm.
The fill covering a drainage channel must be greater than 300 mm.
The end of the drainage channel must extend at least 300 mm beyond the base of the fill supporting the road and the fill in that location must be stabilized at the time of installation.