The Railway Board has classified the railway lines in India based on the importance of the route, the traffic carried, and the maximum permissible speed on the route. The complete classification is given below.
Broad Gauge Routes
All the broad gauge (BG) routes of Indian Railways have been classified into five different groups based on speed criteria as given below.
Group A lines
These lines are meant for a sanctioned speed of 160 km/h:
- New Delhi to Howrah by Rajdhani route
- New Delhi to Mumbai Central by Frontier Mail/Rajdhani route
- New Delhi to Chennai Central by Grand Trunk route
- Howrah to Mumbai VT via Nagpur
Group B lines
These lines are meant for a sanctioned speed of 130 kmph:
- Kalyan-Wadi Raichur-Madras
- Howrah-Bandel-Burdwan-Barharwa over Farakka-Malda town
- Barsoi-New Jalpaiguri
- Delhi-Ambala Cantt-Kalka
- Ambala Cantt-Ludhiana-Pathankot
- Ambala Cantt-Moradabad-Lucknow-Paratapgarh-Mughalsarai
Group C lines
These lines are meant for suburban sections of Mumbai, Kolkata, and Delhi.
Group D and D Spl lines
These lines are meant for sections where the maximum sanctioned speed is 100 km/h.
Group E and E Spl lines
These lines are meant for other sections and branch lines.
D Spl and E Spl routes Based on the importance of routes, it has been decided that few selected routes presently falling under D and E routes will be classified as D special and E special routes. This has been done for the purpose of track renewal and priority allotment of funds. The track standards for these routes will be 60-kg 90 ultimate tensile strength (UTS) rails and prestressed concrete (PSC) sleepers with sleeper density of 1660 per km.
Metre Gauge Routes
Depending upon the importance of routes, traffic carried, and maximum permissible speed, the metre gauge (MG) tracks of Indian Railways were earlier classified into three main categories, namely, trunk routes, main lines, and branch lines. These track standards have since been revised and now the MG routes have been classified as Q, R1, R2, R3, and S routes as discussed below.
Review of track standard for MG Routes
A committee of directors, chief engineers, and additional commissioner of railway safety (ACRS) was formed in 1977 to review the track standards for MG routes.
The committee submitted its report in December 1981, in which it recommended that MG routes be classified into four categories, namely, P, Q, R, and S routes, based on speed criteria. The committee's recommendations were accepted by the Railway Board after certain modifications. The final categories are as follows.
Q routes Routes with a maximum permissible speed of more than 75 kmph. The traffic density is generally more than 2.5 GMT [gross million tonne(s) per km/ annum].
R routes Routes with a speed potential of 75 kmph and a traffic density of more than 1.5 GMT. R routes have further been classified into three categories depending upon the volume of traffic:
(i) R1-traffic density more than 5 GMT
(ii) R2-traffic density between 2.5 and 5 GMT
(iii) R3-traffic density between 1.5 and 2.5 GMT
S routes Routes with a speed potential of less than 75 kmph and a traffic density of less than 1.5 GMT. These consist of routes that are not covered in Q, R1, R2, and R3 routes. S routes have been further subclassified into three routes, namely, S1, S2, and S3. S1 routes are used for the through movement of freight traffic, S3 routes are uneconomical branch lines, and S2 routes are those which are neither S1 nor S3 routes.