POINTS AND CROSSINGS LAYING OF POINTS & CROSSINGS.
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POINTS AND CROSSINGSLAYING OF POINTS & CROSSINGS
METHODS OF LAYINGIN-SITU LAYING In openline, construction and Yard Remodelling (sometimes)
Assembly Shifting Laying Complete Renewal/Laying : MechanisedRenewal/Laying by Parts : Either Manual or Mechanised Prefabrication in Depot Assembly can be done using road crane.
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.
GENERAL PROVISIONS OF IRPWM ON TURNOUT LAYOUTSNo 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.
GENERAL PREPARATION FOR TURNOUT REPLACEMENTField 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.
GENERAL PREPARATION FOR TURNOUT REPLACEMENTRecalculations 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.Coordination with other departments and obtaining CRS sanction (if required). Shifting of fixed structures OHE mast, signalling roads, signal posts, etc, if required.
GENERAL PREPARATION FOR TURNOUT REPLACEMENTThe 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.
MANUAL LAYING OF P&C ON PSC SLEEPERS Preliminary worksSurvey : 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.
MANUAL LAYING OF P&C ON PSC SLEEPERSPreblock worksOn 1 in 12 T/O sleeper nos. 28 to 64 and 73 to 83 can be inserted one by one. Sleeper Nos. 21 to 27 should be kept ready with special bearing plates. Shifting and adjustment of OHE alignment of requiredOEHS should be issued on adjoining tracks.Alternate keys and 2 out of 4 bolts at joints should be removed. Ballast should be removed from top of the sleepers . Speed restriction of 20 kmph should be imposed.
MANUAL LAYING OF P & C ON PSC LAYOUT Block Works One batch (40 men) dismantle switch and approach.Second batch (20 men) remove sleepers and level the ballast bed.Second batch then moves to dismantle crossing portion and take out sleepers from crossing. Third batch (15 men) replaces sl. nos. 21 to 27.The new assembled switch is dragged to proposed site and linked to approach track.( 40 men)Sleepers under crossing and behind HOS are inserted and rails linked.
MANUAL LAYING OF P & C ON PSC LAYOUTBlock Work (contd..)Rail linking for main line is completed and switch portion is packed. Signalling staff start their work.Crossing is fixed and initial packing is given.Traffic block is cancelled and trains are allowed on mainline under speed Restriction treating it as non-interlocked pointTrack on T/O side is completed and traffic permitted on T/O side also.Post Block WorksPacking by UNIMAT;Welding of joints;Recording of measurements.
MECHANISED LAYING OF PSC T/OBy T-28 crawler cranes of M/s AMECA of Italy. One set consists of two self propelled portal cranes, one motorised rail trolley and two non-motorised rail trolley. CRS has permitted speed of 10 kmph when the crane runs on its own power.
T-28 PORTAL CRANESPortal crane can run on rails (using rail wheels) as well as on road (using crawlers). The crawlers can be lifted up or opened laterally to accommodate the sleepers.
The crane can be shifted laterally on the crawlers. These can also be rotated to take angular position. Crawler height can be adjusted individually.
T-28 IN OPERATION
MAINTENANCE OF POINTS AND CROSSINGS
INSPECTIONS Regular Inspection by Engineering Officials (IRPWM Para 237).I/C SE/P.Way and sectional JE/P.Way to inspect all points on passenger running lines once in 3 months and other points once in 6 months by rotation.ADEN to inspect all points on passenger running lines once in a year and 10% of other points every year.Sr. DEN/DEN (L) to inspect certain number of points on passenger running lines every year.Results of Inspections to be recorded in Points & Crossings Register using prescribed proforma.
JOINT INSPECTION WITH S&T BRANCHJoint 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 inspectedResults and compliance to be reviewed at Divisional level. MAINTENANCE REQUIRENTS FROM SIGNALLING CONSIDERATIONS:Switch should be reasonably free to pull- single person single pullProper housing of tongue rail: thick-head bolt,burr on stock rail to be avoidedSwitch should not be out of square.Min. gap between stretcher bar and bottom of rail to be ensured.
INSPECTION OF POINTS AND CROSSINGSBadly worn and damaged tongue rails should be replaced. A tongue rail is classified as badly worn whenIt 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.Has developed knife edge tip over a length of 100 mm any where up-to a distance of 1000mm from its toe. Badly twisted or bent and does not house properly.
INSPECTION OF POINTS AND CROSSINGSTongue rails should be replaced / reconditioned whenVERT. WEAR > 8 MM ( FOR 60 KG.) > 5 MM ( FOR 52 KG AND 90R)LATERAL WEAR > 8 MM ( FOR 60 KG.) > 6 MM (FOR 52 KG AND 90R)
INSPECTION OF POINTS AND CROSSINGSLateral wear at the above said points 13 to 15 mm below stock railsLocations for measurement of vertical wear on TR:Point with 13mm head widthPoint where TR and SR are at same levelThe details are given in Annexure.2/6/1of IRPWM
INSPECTION OF POINTS AND CROSSINGSWear on stock rails should not exceed the following limits-VERT. WEAR - 13 MM ( FOR 60 KG.) - 8 MM ( FOR 52 KG ) - 5 MM ( FOR 90R)LATERAL WEAR FOR CURVE - 8 MM ( FOR GR. A & B ROUTES) -10 MM (FOR GR. C&D ROUTES)FOR STRAIGHT- 6 MM ( FOR GR. A & B ROUTES) - 8 MM (FOR GR. C & D ROUTES)
IMP. MEASUREMENTS ON P & CGauge : Uniform Gauge to be maintained except just ahead of ATS whereNominal gauge if SEA 0-20-00
Throw Of Switch : On BG -Minimum on existing lines : 95 mm Minimum on new works : 115 mmOn MG-Minimum on existing lines : 89 mm Minimum on new works : 100 mm
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 mmCMS 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.
IMP. MEASUREMENTS ON P & C
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.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.
OTHER IMP. PROVISIONS OF IRPWM ON P& C
No change of cant outside ATS and Nose of Crossing for a distance of 18 m on BG and 15 m on MG.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.
CHECK-LIST FOR MAINTENANCE OF PSC SLEEPER LAYOUTSame 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.
WORKING OF UNIMATTAMPINGUNIMAT 08-275/3S has two tamping units each with 8 side tilting tools. Lateral displacement is also possible. This enables to reach difficult locations. The cross section of tools is 20% more than that for normal tampers.If obstacle is encountered, the tyne is tilted out and sleeper is packed with as many pairs as possible. On straight all 8 pairs are used for tamping.M/C Pivot can rotate by 8.50.
UNIMAT-3S 42 Nos.3rd rail lifting
UNIMAT-3S 42 Nos.Points and crossing tamping machineTilting / swirling tools 3rd rail lifting arrangement in (3s) machinesManual lifting of 3rd rail in 2s machines1 t/out per 75 minitues
WORKING OF UNIMAT (contd..)LIFTING In 2S series UNIMATS only two rails are lifted by m/c. Third rail should be lifted manuallyIn 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.
TAMPING OF POINTS & CROSSINGS PRE-TAMPING OPERATIONSEnsure layout & spacing of sleeper as per drawingDefective 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.
TAMPING OF POINTS & CROSSINGS OPERATIONS 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-cmPSC Sleeper 135-140 kg/sq-cm.
TAMPING OF POINTS & CROSSINGS POST TAMPING OPERATIONSChecking and tightening of loose fittings. Replacement of broken fitting.Ballast dressing. Final track parameters should be recorded.
TIPS FOR EFFICIENT TAMPING OF P& CWornout 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.
RECONDITIONING OF POINTS AND CROSSINGS
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.
SYSTEMS FOR RECONDITIONINGIn-situ ReconditioningIs carried out on track either under block or under caution orderAdvantageTraffic block; transportation not requiredReconditioning can be done even if spares are not available (Imp in case of Special. Layouts) .Disadvantage - Difficult to ensure quality.Not suitable for CMS Crossings. Depot Reconditioning : Components are brought to welding depot and then they are reconditioned.Advantage Better QualityDisadvantage Spares, traffic block, transportation arrangement are required. Cost is more.
SUITABILITY FOR RECONDITIONINGOnly suitable components should be taken up for reconditioning.Component should be in sound structural condition.Components containing cracks on the worn-out portion having depths more than 3 mm beyond condemning size should not be taken up for reconditioning .Wear should be within prescribed limit. DPT should be carried out to check for cracks.
DYE PENETRATION TEST
WELDING ELECTRODES Only H3 class of electrodes (H3, H3A and H3B) 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 GMTH3A Min. service life of 25 GMTH3B Min. service life of 35 GMTDiscard 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.
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.
RECONDITIONING OF MM/90 UTS BUILT UP CROSSINGSSurface treatment by cleaning and grindingWelding to be done in flat position .Preheating : The component should be preheated on the surface by to and fro play of oxy-acetylene torch to obtain 2500C to 3000C. Welding to start immediately after preheating. Use short arc length. 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.
RECONDITIONING OF MM/90 UTS BUILT UP CROSSINGS( Continue)Inter-pass temperature of 2500 3000C should be maintained. 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.
BUILT UP CROSSINGS
RECONDITIONING OF CMS CROSSINGSurface treatment by cleaning and grindingWelding 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).
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.
DEPOT RECONDITIONINGCMS CROSSINGS
OTHER STEPS OF RECONDITIONING PROCESSTesting and Inspection Visual Inspection:- Check for surface defects undercut, slag inclusion, porosity, crack etc. Dimensional measurement:- By straight-edge and template DPT or Magnaflux test to detect surface cracksRectification If cracks found, the portion should be gouged either by pneumatic gouging or grinding and remaining portion should be re-examined for crack. If no cracks are found, the portion should be rewelded, ground and inspected.
IMPORTANT STEPS OF RECONDITIONING PROCESSGrinding :- 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 restarted. 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.
SPEED OVER TURNOUTS
SPEEDS ON POINTS & CROSSINGS CRITERIA FOR PERMISSIBLE SPEED ON MAIN LINE : Standard of InterlockingSpeeds on Main Line :Standard I Interlocking 50 kmphStandard II Interlocking 75 kmphStandard III Interlocking UnrestrictedIrrespective of interlocking, speed shall be restricted to 50 kmph in case of a point taking off in the block section
SPEEDS ON POINTS & CROSSINGS CRITERIA FOR PERMISSIBLE SPEED ON MAIN LINE : -Curvature of Main LineNo restriction in case of straight Main Line Main line & Turnout having curvature in opposite direction: CANT given to mainline acts as negative CANT for turnout. This restricts permissible speed on main line. Main line & Turnout having curvature in same direction : CANT given to Main line is also given to Loop Lines. This puts restriction on permissible speed on Main Line.
SPEED POTENTIAL ON TURNOUTSFactors which restricts speed potential on Turnout: Abrupt change in direction at Toe of Switch quantified by Switch Entry AngleAbsence of TransitionDeficiency of Super elevation on leadDiscontinuity at CrossingUn-transitioned entry from curved lead to straight crossingStraight or un-flexed crossing. However out of above only SEA has significant bearing on speed potential of T/O at low speeds.
SPEED POTENTIAL ON BG
Description Speed (kmph)1 in 8 T/O with St. SW101 in 8 T/O with Cu. Sw.251 in 12 T/O with St. Sw151 in 12 T/O with Conv. Cu. Sw. (SEA : 00 27 35)401 in 12 T/O with Impr. Cu. Sw.501 in 12 T/O with Thick Web Sw. 501 in 16 T/O with Conv. Cu. Sw.501 in 16 Impr.T/O with Cu. Sw. 651 in 20 Impr.T/O with Cu. Sw. 85
SPEED POTENTIAL ON BG
Description Speed (kmph)1 in 8 Symm. Split T/O with Cw. Sw401 in 12 Symm. Split T/O with Impr. Cw. Sw701 in 16 Symmetrical split T/O with Cu.Sw. 75
SPEED POTENTIAL ON MG
DESCRIPTIONSPEED (KMPH)1 in 12 T/O with Cu. Sw251 in 12 T/O with St. Sw.151 in 8 T/O with Cu. Sw151 in 8 T/O with St. Sw101 in 8 Symm. Split T/O with Cu. Sw.151 in 8 Symm. Split T/O with St. Sw.10
Increase in speed of turnouts Rly bd letter no. 2000/CE-II/TK/9 dtd. 24/1/07Speed of 30 kmph can be permitted on turnouts, provided the following conditions are satisfied. Higher speed turnouts are provided on a reasonably long section in a continuous stretch.
Turn in curves and running loops on which higher speed is permitted, are suitably strengthened. Arrangements for detection of facing points(including siding points) available in loop line, if anyHigher speed turnouts are those which permit a speed of 30 kmph or higher as indicated below -
As a substantial number of 1 in 8.5 symmetrical split turnouts are existing on running lines, it is feasible to increase the sped upto 40 kmph only, in spite of the fact that turnouts with higher speed potential are available. Speed upto 40 kmph can be permitted if the following additional provisions (over and above para 1) are fulfiled. Turnouts should be on PSC sleepers
Aspects of home signal to be modified suitably so as to enable the driver to know whether he is passing through the loop line/main line or has to stop on the same so that he can control the train speed accordingly. This can be achieved by arranging the signalling as shown in Annexure I. The two sketches Annexue 1A & 1B are for single distant and double distant territory. The aspects of only those signals have been specified which are coming in the route of the train
LED signal should be provided for all signal aspects to realize the full potential of the arrangement through improved visibility of signals. Detailed instructions stipulating the track structure for permitting 30 kmph speed on turnouts have been incorporated in para 410 of IRPWM vide correction slip no. 94. Based on the experience with 40 kmph, provisions of IRPWM can be considered for suitable amendment.
The speed over turnouts in a section can be further increased to 50 kmph provided all the 1 in 8.5 turnouts on running lines of the proposed section have been replaced by such turnouts which permit a speed of 50 kmph or higher. Para 4.10 of General Rules 1978 specifies that speed over turnout and crossovers shall not exceed15 kmph, unless otherwise prescribed by approved special instruction, which may permit a higher speed. Suitable provision for this shall be made with approved special instructions to permit such higher speeds. Increase in speed on turnouts shall be taken up as detailed above. Top priority shall be accorded to achieving a speed 30 kmph on Group A routes.
Detailed instructions for permitting 30 kmph speed on turnouts (para 410)Length of Section -should cover a number of contiguous stations at a time The works described below, should cover all the running loops on the stretch of line taken up.Turnouts - Speed, in excess of 15 kmph, should be permitted on turnouts laid with ST or PRC sleepers only. All turnouts on the running loops shall be laid with curved switches, with minimum rail section being 52 Kg. All rail joints on these turnouts should also be welded to the extent possible.
(ii) Track on running loops - Speed in excess of 15 kmph, should not be permitted on running loops laid with wooden sleepers. The minimum track structure on the running loops should be 90R rails laid as Short Welded Panels, M+4 density on PRC, ST, CST- 9 sleepers and 150 mm ballast cushion. Out of 150 mm total cushion, clean cushion of 75 mm at least should be available. Proper drainage to be ensured.(iii) Turn-in curves - Speed in excess of 15 kmph, should not permitted on Turn-in curves laid with wooden sleepers. Turn-in curves should be laid with the same rail section as on the turn-out with PRC, ST or CST-9 sleepers with sleeper spacingbeing 65 cm centre to center (maximum).Turn-in curve should conform to Para 410 (2) of IRPWM and especially so in respect of curvature of the lead curve.
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 turn-outs.if CST-9 sleepers are used in running loops or turn-in curves :- (i) There is no crack or fracture at rail seat in two consecutive sleepers. (ii) There is no excessive wear of lug and rail seat. (iii) All the fittings, keys, cotters and tie bars are fitted properly. Rail is held firmly with sleepers. (iv) Tie bars should not be broken or damaged by falling brake gear, wagon parts etc. and they should not have excessive corrosion or elongated holes. The corrosion of tie-bars inside the CST-9 plate should be especially checked as this results in their removal and adjustment becoming difficult.if ST sleepers are used in Turnouts, Turn-in curves or running loops:- (i) There is no crack or fracture at rail seat in two consecutive sleepers.
(ii) There is no excessive wear of lug, MLJ andrail seat.(iii) All the fittings are effective and rail is heldwith sleepers properly.(iv) The sleepers and fittings do not have excessivecorrosion, elongated holes etc.