As per the Indian Railways, the gauge is defined as:
- Athe centre to centre distance of two track rails
- Bthe clear distance between inner faces of two track railsCorrect
- Cthe length of the sleeper - width of the sleeper
- Dthe clear distance between outer faces of two track rails
Solution
Concept
Gauge is the clear distance between the inner (running) faces of the two rails of a track.
Step-by-step solution
1. Gauge is the space between the two rails of a track. 2. Indian Railways measures it between the inner faces of the rails (gauge faces). 3. It is measured a little below the rail top (about 13 to 16 mm). 4. So gauge is the clear distance between the inner faces of the two rails.
Explanation
The wheel flanges run along the inner faces of the rails. So the gauge is measured as the clear distance between these inner faces. For example, Broad Gauge is 1676 mm.
Why the other options are wrong
A: centre to centre distance of rails is more than the gauge. C: sleeper length minus width has no link with the gauge. D: distance between outer faces adds the rail head widths, so it is wrong.
Shortcut
Gauge = inner face to inner face of rails.
Common mistake
Taking the centre to centre distance of the rails as the gauge.
Correct answer: B) the clear distance between inner faces of two track rails