8.6.4.5. Service Road and ‘Dowla’ For proper maintenance and inspection of irrigation channels, service roads are provided on both sides of main canals and major branches. In the case of smaller branches and distributaries, a service road on only one side (usually, the left bank) is provided. The inspection road on main canals is usually about 6.0 m wide and should not be smaller than 5.0 m wide. The canal roads are generally unsurfaced but made motorable by using compacted and dressed earth material. If the canal road is to be used for other purposes as well, it should be metalled and surfaced.
If a road is constructed on the ground along a banked canal, the canal is not visible while driving along the road. As such, the vehicle has to be stopped frequently at places to have a look at the canal. Thus, proper inspection of the canal is difficult. This problem can be avoided if the road and the bank are combined together, [Fig. 8.8(b)] and a ‘dowla’ of about 0.5 m height and about 0.5 m top width is provided for safety reasons. The level of the road is kept about 0.3 to 0.75 m above full supply level of the canal.
