A good drainage system should satisfy the following requirements.
Surface water should not percolate to track One of the basic requirements of a good track drainage system is that surface water from rains and adjacent areas should not percolate and seep into the formation of the track.
Effective side drains The size of the side drains should be adequate with a proper slope, so that they effectively carry all the surface water away.
Longitudinal drains to be saucer-shaped The longitudinal drains provided between two tracks should preferably have a saucer-shaped cross section so that they can collect water from both sides.
Provision for clearing and inspection The drains provided for drainage should be such that they can be inspected and cleared periodically.
Drain top to be below cess level Normally, the drain top should not be above the cess level for the effective drainage of the ballast bed.
No erosion of banks The flow of water along the slope and across the track should not cause erosion of the banks or the slopes of the banks.
Formation to be of good soil Ideally, the formation and subgrade should be made of a pervious, coarse-textured soil. Such soils are more permeable, retain less capillary water, and respond more favourably to a surface drainage system.
Proper sub-surface drainage Arrangements should be made for a good subsurface drainage system to drain off the water being retained is the track. This is more relevant in the case of defective formations.
Proper outfall Longitudinal drains should be designed so as to provide a proper outfall, from where the water can eventually drain off.
Special arrangements for waterlogged areas and other difficult situations A
good track drainage system should have special arrangements for the drainage of waterlogged areas and for all other related perennial problems.