Cross Drainage Work:
Several natural streams, rivers and canals cross the road. They have to be led across the road through culverts and bridges. That given structures is known as cross-drainage works. The subject is dealt with in addionally.
Side drains are needed for collecting the surface run-off and leading it to a natural stream. In hill roads, the side drains are generally V-shaped and are lined with dry stones, as in Figure(a). A trapezoidal drain in masonry is shown in Figure(b).
(a) Triangle Drain
(b) Trapezoidal Side Drain
Figure : Typical Designs of Side Drains on Hill Roads
In roads in plains, the run-off water from the road embankment is led to a side ditch which may be lined or unlined. A typical arrangement is shown in Figure. The dimensions of the drain are determined from the run-off, the longitudinal slope and rugosity coefficient using Manning's formula.
Figure: Side Ditches along Roads in Plain Areas