Prohibited Locations for LWR

Due to the technical problems arising on account of the use of long welded rails, the Indian Railways have specified locations where the laying of LWRs is prohibited. These locations are listed below.

(a) New constructions and doublings of lines, where the formation and the track is not fully stabilized. However, if mechanical compaction of the earthwork is done, LWRs may be laid on the new lines at the initial stage itself with the approval of the chief engineer.

(b) Locations where rails are subjected to heavy wear, corrugation, or corrosion, or require frequent renewal.

(c) Locations where the formation is weak and track deformations are extensive, which may lead to buckling.

(d) Locations where the formation soil is susceptible to pumping and the ballast is likely to get heavily contaminated, thereby necessitating the frequent opening of the track and the screening of the ballast.

(e) Locations where frequent breaches, flooding, and subsidence may occur.

(f) On curves with a radius sharper than 500 m. In the case of reverse curves, the limiting value is 1500 m.

(g) The steepest gradient permitted for LWRs is 1 in 100. At every change of gradient, vertical curves should have the minimum radii listed in Table 17.1.

Table 17.1 Minimum radii for vertical curves at gradient changes


Minimum radius (m)

Group A


Group B


Groups C, D,and E


All MG routes


All other locations besides those listed in Table 17.1 are known as permitted locations for LWRs.

Theory of Long Welded Rails | RAILWAY ENGINEERING | Track Structure for LWR