Question with Answer - Civil Engineering (LDCE)
Question -1 Describe the benefits of tamping in design mode.
Also write down the pre tamping and post temping operations for tamping of T/outs including the points to be observed during tamping of turnouts for better retention of packing?
Q.1. Describe the benefits of tamping in design mode. Also write down the pre tamping and post temping operations for tamping of T/outs including the points to be observed during tamping of turnouts for better retention of packing?
Ans: - BENEFITS OF TAMPING IN DESIGN MODE: - Working of tamping machine in smoothening mode reduces the track defects viz unevenness, cross levels and alignment to only limited extent. Wherever, the tamping in design mode corrects the track parameters up to a design value thereby eliminating the track defects to a larger extent. Thus, good track geometry is achieved by working of tamping machines in design mode. Comparatively longs sags and dips in track are eliminated by designing the vertical profile of the track. Also the long alignment defects are removed by using the sufficiently long chords for designing the slews. However, obligatory points are to be kept in mind while designing the vertical profile and slews for tamping in design mode.
PRE-TAMPING OPERATIONS FOR TAMPING OF TURNOUTS: -
i) Layout including spacing of sleepers as per
relevant drawings shall be ensured.
ii) Battered/Worn out crossings should be
reconditioned or replaced.
iii) Warped/bent or worn-out sleepers under
crossing should be replaced.
iv) The joints of the CMS crossing should be made
gapless.
v) Avoidable joints in turnout portion and on its
approaches should be welded.
vi) High points on the turnout and its approaches
should be determined and general lift should be decided. General lift of
minimum 10mm must be given.
vii) The field survey should be carried out to
design the vertical profile/general lift and slews for rectification of
alignment defects.
viii) Ballast shall be heaped up in the tamping
zone to ensure effective packing.
ix) Hogged, battered and low joints shall be
attended.
x) Track drainage should be improved for better
retention of packing.
xi) Deficient fittings and fastenings should be
made good and properly tightened.
xii) Wooden blocks and joggle fish plates shall be removed temporarily ahead of tamping.
OPERATIONS DURING TAMPING OF TURNOUTS: -
i) For packing turnout, main line is to be tamped
first. While tamping main line, the additional lifting arrangement lifts the
turnout side rail also. The lifted end of sleepers should be adequately
supported on wooden wedges till it is packed/tamped.
ii) The machine carries out correction of alignment
and levels on main line portion. On the turnout side, only tamping without
lifting and lining shall be done.
iii) The squeezing pressure to be applied should be
as follows: -
a) ST/Wooden sleepers – 110-115 Kg/Sqcm
b) PSC sleepers – 135-140 Kg/Sqcm.
iv) In case there is hindrance to achieve adequate
penetration of tools, penetration assistance system should be used to facilitate
insertion of tools in ballast and to accelerate lowering of tamping
units.
v) During and before tamping, S&T and
Electrical staff should also be associated to complete their portion of
work.
vi) Tamping of all sleepers should be ensured
specially in switch portion by opening out all the stretcher bars including
leading stretcher bar by taking proper disconnection of the point through
S&T supervisor at site.
vii) The parameters of tamped track should be checked immediately after tamping for cross level and alignment and necessary corrective action should be taken.
POST TAMPING OPERATIONS: -
i) All S&T and Electrical connections removed
before tamping shall be restored back.
ii) All broken/missing fittings and fastenings
should be recouped and loose ones
should be tightened.
iii) The ballast should be dressed neatly. Proper
consolidation of ballast between the
sleepers should be done.
iv) Final track parameters should be recorded.
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