If a is average number of peaks more than 10 mm of uneveness per kilometre, b is average number peaks more than 6 mm for gauge variation per kilometre and c is average number of peaks more than 2 mm twist per metre, then composite current recording index (I_{c}), as recommended by Indian Northern Railways, is
If S is the switch angle and `alpha` is diamond angle, r is the radius of slip, the distance between middle point slip and the nose of obtuse crossing, is
If the standard length of a crossing is 480 cm, the number of crossing is
If D is distance between centres of two parallel tracks of gauge G with entire curved leads and equal angles of crossing, total length of crossover, is
If w is width of sleepers, s is sleeper spacing and d is depth of ballast then