Q. & A - Describe the benefits of tamping in design mode.

 

Q. no. 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 correct 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.