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POINTS AND CROSSINGS

POINTS AND CROSSINGS. IMPORTANT ASPECTS IN LAYING & MAINTENANCE. METHODS OF LAYING. IN-SITU LAYING / REPLACEMENT – In openline, construction and Yard Remodelling (sometimes) Assembly – Shifting – Laying Complete Renewal/Laying : Mechanised

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POINTS AND CROSSINGS

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  1. POINTS AND CROSSINGS IMPORTANT ASPECTS IN LAYING & MAINTENANCE

  2. METHODS OF LAYING • IN-SITU LAYING / REPLACEMENT – In openline, construction and Yard Remodelling (sometimes) • Assembly – Shifting – Laying • Complete Renewal/Laying : Mechanised • Renewal/Laying by Parts : Either Manual or Mechanised • Prefabrication in Depot – Assembly can be done using road crane.

  3. GENERAL PROVISIONS OF IRPWM ON TURNOUT LAYOUTS • Para 410 stipulates that • T/Os on passenger lines should not be laid with ST. SW. sharper than 1 in 12.If there is constraint of space, 1in 8.5 T/O with CU.SW. may be laid. • Sharper (than 1 in 12) may be used when the turnout is taken off from outside of a curve restricting the radius of lead curve within following limits - BG – 350 m MG – 220 m NG – 165 m.

  4. GENERAL PROVISIONS OF IRPWM ON TURNOUT LAYOUTS • Emergency cross over with trailling direction on passenger line in double or multiple line can be provided with 1 in 8.5.

  5. No change of superelevation overturn-outs • There should be no change of cantbetween points and 20 metres on outside the toe of the switch and the nose of the crossing respectively,except in cases where points and crossings have to be taken off from the transitioned portion of a curve.

  6. Contd. … • Normally, turn-outs should not be taken off the transitioned portion of a main line curve. However, in exceptional cases, specific relaxation may be given by the Chief Engineer of the Railway. • In such cases change of cant and/or curvature may be permitted at the rates specified in para 407 of IRPWM

  7. GENERAL PROVISIONS OF IRPWM ON TURNOUT LAYOUTS • No turn in curve should be sharper than lead curve of 1 in 12 simple turnout.However if track centres are inadequate 220m radius on BG and 120 on MG can be permitted with strengthening of turn in curve. • 1 in 8.5 T/O should not be laid on inside of curve.

  8. GENERAL PREPARATION FOR TURNOUT REPLACEMENT • Field inspection to check site conditions, approach, presence of electrical & signalling gears, posts, boards etc. which may cause obstruction; availability of ballast etc. • Arranging adequate space for assembly by necessary tools & plants and good quality artisan. • Checking completeness of all components of P&C as per parts list. Checking of important dimensions.

  9. GENERAL PREPARATION FOR TURNOUT REPLACEMENT • Recalculations of overall length vis a vis track centres. Examine scope/need for improvement Distances to be measured accurately and layout to be marked . • The proposed location of SRJ, ATS, TNC, Glued Joints etc. should be marked on ground. • Planning the rail cuts in the assembly to minimise wastage. • Obtaining CRS sanction (if required). • Shifting of fixed structures – OHE mast, signalling roads, signal posts, etc, if required.

  10. GENERAL PREPARATION FOR TURNOUT REPLACEMENT • The mid-ordinate and the quarter ordinates of the tongue rails and stock rails should be checked and rectified. • If existing sleepers are wooden or ST, provision has to be made for additional depth of PSC sleeper along with 300/250 mm ballast cushions. • The existing ballast should be deep screened and recouped to match levels with approach track. • Spacing of sleepers to be measured along the mainline starting from beginning.

  11. MANUAL LAYING OF P&C ON PSC SLEEPERS • Preliminary works • Survey : Measure & check existing layouts. Examine scope/need for improvement. • Mark proposed SRJ, ATS, crossing position & location of sleepers on lead and crossing portion. • Assemble the switch on staging. • Check housing of TR with SR and Throw.

  12. MAINTENANCE OF POINTS AND CROSSINGS

  13. JOINT INSPECTION WITH S&T BRANCH • Joint Inspection by SE/P.Way (I/C or Sect) and SE/Signal • All interlocked points to be inspected jointly once in a quarter /half-yearly. • Mainly switch portion is inspected • Results and compliance to be reviewed at Divisional level. • MAINTENANCE REQUIRENTS FROM SIGNALLING CONSIDERATIONS: • Switch should be reasonably ‘free’ to pull- ‘single person single pull’ • Proper housing of tongue rail: thick-head bolt,burr on stock rail to be avoided • Switch should not be out of square. • Min. gap between stretcher bar and bottom of rail to be ensured.

  14. MAINTENANCE OF POINTS AND CROSSINGS • Badly worn and damaged tongue rails should be replaced. A tongue rail is classified as badly worn when • It is chipped/cracked over small lengths aggregating to 200 mm within a distance of 1000 mm from toe .Chipped length will be portion where tongue rail has worn out for a depth of more than 10 mm over a continuous length of 10 mm. • Badly twisted or bent and does not house properly.

  15. IMP. MEASUREMENTS ON P & C • Gauge : Uniform Gauge to be maintained except just ahead of ATS where • Nominal gauge if SEA<= 0-20-00 • Nominal+6mm if SEA > 0-20-00 • Throw Of Switch : • On BG -Minimum on existing lines : 95 mm Minimum on new works : 115 mm

  16. IMP. MEASUREMENTS ON P & C • Vertical Wear on crossing (Wing Rail & Nose) • Measured at 100 mm from ANC. • Rajdhani & Shatabdi Routes : As a good maintenance practice,crossing and wing rails should be planned for reconditioning on reaching following values: • Built –up crossing: 6 mm • CMS crossing : 8 mm • Other Routes: 10 mm. • In case of CMS crossings 2.0mm in case of 52kg section and 2.5mm in case of 60kg section should be deducted from observed wear measurements to account for cross slope.

  17. BUILT UPCROSSINGS

  18. OTHER IMP. PROVISIONS OF IRPWM ON P& C • No Junction Fishplate at SRJ or HOC. At least one rail to be of same section. • Provide spherical washers properly. • Creep anchors and box anchoring of one rail length. (in case PSC sleepers not required) • Desirable to weld SRJ and lead curve joints. • Lubrication of gauge face of tongue rail. • ST sleepers – Wooden blocks under crossing in case of ST sleepers. • Gauge Tie Plate should be used on proper locations.

  19. OTHER IMP. PROVISIONS OF IRPWM ON P& C • In case of straight switches, correct amount of bend should be given to the stock rail on the turnout side at the theoretical toe of switch. • Tongue rail should bear evenly on all the side chair. When the tongue rail is in closed portion, it must bear evenly against distance studs or blocks. • Insertion or removal of P & C in a running line affecting layout must be carried out only after obtaining sanction of CRS.

  20. CHECK-LIST FOR MAINTENANCE OF PSC SLEEPER LAYOUT • Same track structure for one rail length on the three sides. • Weld joints as specified. • Gapless joints as specified. • Grind gauge face of stock rail if burr is there. • Regular maintenance by UNIMAT. • Proper maintenance of CMS crossing.

  21. 3rd rail lifting UNIMAT-3S 42 Nos.

  22. UNIMAT-3S 42 Nos. • Points and crossing tamping machine • Tilting / swirling tools • 3rd rail lifting arrangement in (3s) machines • Manual lifting of 3rd rail in 2s machines • 1 t/out per 75 minitues

  23. WORKING OF UNIMAT (contd..) • LIFTING • In 2S series UNIMATS only two rails are lifted by m/c. Third rail should be lifted manually • In 3S series UNIMATS there is an ‘arm’/lifting hook for lifting the third rail. • With 4S series of m/c the whole T/O can be tamped in one go. The M/C moves laterally. • With 3S series of M/C – ML is aligned packed and levelled. LL is only packed.

  24. TAMPING OF POINTS & CROSSINGSPRE-TAMPING OPERATIONS • Ensure layout & spacing of sleeper as per drawing • Defective crossing should be reconditioned/replaced and sleepers attended. • High points on the turnout and approaches should be determined and general lift decided. • Minimum general left should be 10 mm Note : These are in addition to the regular temping operations prescribed for any tamping operation.

  25. TAMPING OF POINTS & CROSSINGSOPERATIONS DURING TAMPING • Mainline to be tamped first. • The lifted end of sleepers should be adequately supported on wooden wedges till it is packed/tamped. • Alignment and level correction on main line. Only tamping on turnout side. • Squeezing pressure: ST/Wooden Sleeper 110-115 kg/sq-cm PSC Sleeper 135-140 kg/sq-cm.

  26. TAMPING OF POINTS & CROSSINGSPOST TAMPING OPERATIONS • Checking and tightening of loose fittings. • Replacement of broken fitting. • Ballast dressing. • Final track parameters should be recorded.

  27. TIPS FOR EFFICIENT TAMPING OF P& C • Wornout crossings should be replaced in advance. • Fittings and Fastenings should be recouped. • Minimum 10 mm lift is desirable. More if required (depending on track geometry, ballast availability, S & T gear position etc.) • If unevenness in track is high, longer approach should be tamped. • On PSC Layout 1 insertion is adequate for 30 mm lift. On ST and wooden layout 2 insertions are required. • When mainline is being tamped, T/O should be kept supported by wooden wedges. • Some areas are not reached by M/C. These should be tamped by Off-track tampers or packed manually.

  28. RECONDITIONING OF POINTS AND CROSSINGS

  29. NEED FOR RECONDITIONING • The point and crossing components gets worn out due to passage of traffic and the wear reaches permissible limits in due course of time. • It is neither economical nor practical to replace them straight away. The life of these components can be prolonged by reconditioning and thus these can be utilized to maximum extent.

  30. WELDING ELECTRODES • Only H3 class of electrodes (H3, H3A, H3B and H3C) manufactured by firms approved by RDSO are to be used. RDSO to circulate list every July. • Traffic carrying capacity of electrodes (of H3 class) • H3 – Min. service life of 15 GMT • H3A – Min. service life of 25 GMT • H3B – Min. service life of 35 GMT • H3C – Min. service life of 50 GMT • Discard electrodes with cracked / damaged flux covering. • Damp Electrodes not to be used. Either packing of electrodes should be absolutely intact and all the electrodes should be consumed within six hours of opening of pack. Or electrodes to be dried at 1300- 1700 for at-least one hour. • 4 mm dia electrodes to be used for welding.

  31. Reconditioning of Switch : Recondition the Stock Rail first. A wornout tongue rail shall be reconditioned in closed position i.e. resting against the stock rail. In case of broken tip the TR is to be built up initially in the open condition and thereafter it should be closed with SR to attain final profile. • Welding Current – The current range as recommended by the manufacture of electrode should be adhered to. • Electrical Appliances – All appliances should be properly earthed. Generator should be capable of supplying 200 amperes at 60% duty cycles.OCV (Open Circuit Voltage) should be in the range 65V to 85V.

  32. RECONDITIONING OF CMS CROSSING • Surface treatment by cleaning and grinding • Welding operations to be done in flat position. • Preheating not required. • The temp during welding process not to go up beyond 150 0C. • Temperature to be controlled by by proper intervals between the runs and by means of compressed air jet or water quenching . Or, the crossing may be kept submerged in water bath with only top 1 cm above water level. • Welding cycle should be short (2 min).

  33. Care to be taken to fill the crater to the full weld size before breaking the arc. • At restart arc should be stuck ahead of crater and then drawn back so as to fill the crater. • Each bead should be thoroughly peened with ball peen hammer. • While depositing the adjacent layer about 50% of previous layer should be covered. • Weld metal to be deposited to provide an excess of 3 mm to be finished by grinding.

  34. DEPOT RECONDITIONINGCMS CROSSINGS

  35. IMPORTANT STEPS OF RECONDITIONING PROCESS • Grinding :- The reconditioned area should be ground to the original contour. Grinding wheel should be continuously moved back and forth and not stopped at one location to avoid high localised heating and subsequent cooling. • Passage of Trains :-Trains can be passed at normal speed over the weld metal on crossing even before completion of welding. After passage of train, welding can be started again. However, weld metal should be allowed to cool for 2 to 3 minutes before allowing passage of train.

  36. Thanks

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