4 7Strengthening of loop lines for 30 Kmph

4. 7_Strengthening of loop lines for 30 Kmph / 50 Kmph Periods 2

Up-gradation of speeds on Turnouts and Loops to 30 Kmph • Length of Section– • Up-gradation of speeds on turnout should cover a number of contiguous stations at a time so as to derive a perceptible advantage of the higher speed in train operation. • The works described in next slides should cover all the running loops on the stretch of line taken up.

Up-gradation of speeds on Turnouts and Loops to 30 Kmph Turnouts • Speed, in excess of 15 Kmph, should be permitted on turnouts laid on PSC sleepers only. • All turnouts on the running loops shall be laid with curved switches, with minimum rail section being 52 kg/m. • All rail joints on these turnouts should also be welded to the extent possible.

Up-gradation of speeds on Turnouts and Loops to 30 Kmph For different type of curved switches permissible speed are as under– Sl. No. 1. 2. 3. Type of Turnout 1 in 8½ curved switch Permissible speed 15 Kmph 1 in 8½ symmetrical split 30 Kmph with curved switches 1 in 12 curved switch 30 Kmph

Up-gradation of speeds on Turnouts and Loops to 30 Kmph Track on running loops– • The minimum track structure on the running loops should be 52 Kg/m rails laid as Short Welded Panels, sleeper density 1540 Nos. per km and 150 mm clean ballast cushion. • Proper drainage of the area should also be ensured. Turn-in curves– • Turn-in curves should be laid with the same rail section as on the turnout with PSC sleepers with sleeper spacing being 65 cm centre to centre (maximum).

Up-gradation of speeds on Turnouts and Loops to 30 Kmph • Radius of turn-in-curve should generally be not less than 350 metre. • Where it is not practicable to achieve the radius of curvature of turnin curves as 350 m on account of existing track centres for the turnout taking off from curves, the turn-in curves may be allowed upto a minimum radius of 220 m subject to the following– • (i) such turn-in curves are provided on PSC sleepers only, with sleeper spacing same as that for the main line. • (ii) full ballast profile, same as that for the main line, is provided.

Up-gradation of speeds on Turnouts and Loops to 30 Kmph • Extra shoulder ballast of 150 mm should be provided on outside of the turn-in curve. • The frequency of inspection of turn-in curves should be same as that for main line turnouts.

Up-gradation of speeds on Turnouts and Loops to 50 Kmph • Turnouts – speed of 50 Kmph should be permitted on turnouts laid with Thick web curved switches on PSC sleepers. • Minimum 150 mm clean ballast cushion should be ensured. • All joints except at the end of tongue rail and crossing should be welded.

Up-gradation of speeds on Turnouts and Loops to 50 Kmph • Following turnouts may be used for speeds 50 Kmph & more – Sl. No. Type of Turnout 1 60 Kg 1 in 12 Turnout on TWS Speed Potential KMPH 50 2 60 Kg 1 in 16 Turnout on TWS 65 • In case above said turnouts are taking off from curve the speed should be decided on the basis of Resultant Radius and cant provided, if any.

Up-gradation of speeds on Turnouts and Loops to 50 Kmph Turn in Curve – Turn in curve/ Connecting curve should have speed potential of 50 Kmph or more which is calculated on the basis of radius & Cant. • If there is no cant on Turn in curve/ connecting curve it should be laid with minimum radius of 441 m. • Turn-in curves should be laid with the same rail section as on the turnout with PSC sleepers with sleeper spacing being 65 cm centre to centre (maximum). •

Up-gradation of speeds on Turnouts and Loops to 50 Kmph Track on running loops– • The minimum track structure on the running loops should be 52 Kg/m rails laid as SWR/LWR, sleeper density 1540 Nos. per km and 250 mm total ballast cushion out of which 150 mm clean ballast cushion should be available.

Up-gradation of speeds on Turnouts and Loops to 50 Kmph • Requirements from Signalling – • Clamp lock point machine shall be provided for speed > 30 Kmph • Arrangements for detection of facing points to be available in loop lines, if any. • Aspects of Home signal to be modified suitably so as to enable Loco pilot to know whether he has to stop or going through and can control the train accordingly. • The visibility of loop line starter should be such that loco pilot entering the loop line at 50 kmph is able to see the aspect of starter signal • Some times a repeater signal is required to be installed if loop lines fall in curve.

Requirements from OHE – • Similarly OHE deptt. has to account for this increase in speed on loop lines from various technical considerations and give clearance for such speed raising. If required they have to adjust the OHE to make it suitable for 50 KMPH

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