Thursday, 25 February 2016

MAINTAINANCE OF TRACKS

Necessity of Maintainance:-

Once track is laid, yards are constructed, signaling systems are installed and track is opened to traffic, immediately then, the necessity of maintenance arises due to following reasons:
1)The strength of track structure goes on deteriorating or reducing due to movement of high speed trains, heavy axle loads and repetition of loads. The elastic structure of railway track thus disturbed in alignment, gauge and surface level of rails.

2)The track structure is also subjected to other deterioring effects like rain water, action of sun & winds. The wear & tear of rails, and of rolling stock is then bound to take place due to their adverse effects.

3)The track structure has to bear too many other effects due to curvature, speed & load, particularly on curves, crossing, bridge approaches and at level crossings.
  It is therefore essential to maintain the track in good condition so that trains may run over it safely, comfortably and efficiently at specified speeds. If track is not properly maintained, firstly, this would result in faster wear and tear, rough riding & discomfort to the passengers & then may result in extreme cases of derailments of trains with possible loss of life & property.

The maintenance of railway track can be carried out either manually or by use of mechanical appliances or by combination of both.
In India conventional maintenance is carried out by means of manual labour and hand tools. In America & other developed countries,    mechanical appliances are largely used.
The maintenance of track can be divided into two parts :-

1)Daily maintenance:- Daily maintenance is carried out by the full time staff maintained throughout the year. The use of maintenance gangs, all along the railway track is made. The railway track is divided in suitable sections to 5 to 6 km length. One gang is attached 
to each section for maintaining that section in good condition.

2)Periodic Maintenance:- Periodic maintenance is carried out after an interval of 2 to 3 years. During periodic maintenance , the gauge, level, alignment, points & crossing etc are thoroughly checked, the defects are detected, the causes are determined & finally remdial measures taken.. The track is made perfect condition by removing all its major & minor defects.
The maintenance of track includes the following items of maintenance in good condition.
 (1) Surface of rails.            
 (2)  Track Alignment.
 (3) Gauge.                           
(4)  Proper Drainage.
 (5) Track Components.     
 (6)  Bridges & its Approaches.
 (7) Rolling Stock.            
 (8)   Points & Crossing
 (9) Level Crossings            
(10) Tunnels.
1) Maintenance of surface of rails:- The top surface of two rails should be maintained properly on straight lengths. The top surface should be kept in same plane or level, whether the track is on rising gradient or falling gradient or on a level stretch.
On curves- The outer rail should be kept at prescribed height above the inner rail. i.e proper superelevation should be maintained. Maintenance of surface of rails involves the following operations:-

(A)Packing.
 (B) Surfacing the track.
(C) Boxing & Dressing the track.
(D) Levelling of the track.
(E) Lifting of the track.
 (F) Surface defects & remides.
(G) Spot packing & Track lifting.

2) Maintenance of track alignment:- If the track goes out of alignment. i.e, shifts sideways on the on the straights or at curves due to any one of the following causes, it may result in bad riding & derailments. Maintenance can be done by following operations:-
A) Realignment of straight tracks:- The correction of alignment of straight track is done by 2 methods.
   (i) Bye use of crow bars.
  (ii) By use of track liners.

(B) Realignment of curved tracks:-  Minor adjustments in alignment can be done by means of crow bars or liners as fox straight tracks.
Major adjustments are done by:-
* Checked by human eye.
*Theodolite.
*String line method.

3) Maintenance of gauge:-  Uniformity of the gauge throughout should be properly maintained as it is more important than to provide a proper gauge. With a non-uniform gauge, the riding qualities of the track are adversely affected.
It is maintained by tightening the track fittings & proper maintenance of correct joints, creep anchors etc. instruments used are                            
a) Gauge rod and
 b) Rail brace.

4) Maintenance of proper drainage:- Drainage is most important to ensure smooth riding & longer life of track. The proper drainage of track can be maintained by following methods:-
 (a) Cleaning of ballast
 (b) Cleaning of cess
(c) Surface drainage
(d) Underground drainage.




5) Maintenance of track components:- This includes the maintenance and renewal of rails, track fittings and sleepers.
 In track fittings like Fish plates- The graphiting of fish plates is done for the following purpose:
*To protect the fish-plates against corrosion.
*To allow free expansion and contraction of rails.
*To increase the life of fish plates and bolts.

6) Maintenance of Bridge and its Approaches:- The maintenance of bridge & its approaches over which track passes is of great importance. If accident take place at such spots, it results in huge loss of lives and national property. Maintenance is done by
a) Maintenance of foundation
  b) Maintenance of sub-structure & protection works
c) Maintenance of super structure
d) Maintenance of track on bridge and its approaches.

7) Maintenance of Rolling stock:- The rolling stock, which consists of locomotive ,coaches & wagons, should be maintained in good working condition. For maintaining rolling stock following measures are done:
* Lubrication of all the reciprocating parts & bearings with suitable lubricant should be done.
* All axles after 3 lacs km should be replaced by new once.
* The locomotive boilers should be renewed after every 15 years.

8) Maintenance of points and crossing:- The switches or points are regarded to be the weaker points of the track & most of the derailments occur at points & crossing locations only. so it is maintained by:
* The gauge should be perfect at all places except at the toe where the gauge should be a little slack.
* The ballast should be repacked and screened periodically.
* Adequate drainage must be maintained at all points.

9) Maintenance of level crossing:-In level crossing the road is kept in rail level & grooves are left in road surface along the inner edge of rail for wheel flange. Such an arrangement, packing is not possible without disturbing the surface. To maintain level crossings certain measures are taken:
* The rails and fittings be tarred once a year by opening out the level crossings.
* On level crossing road traffic is low use water bound macadam in the area of crossing, if road traffic is high use bituminous pavement, so track is least disturbed.

10) Maintenance of tunnel:- For maintaining the tunnel certain measures should be taken:
*Portals at the ends should be checked. Any defect in signs of slip above top, crushing or cracking of masonry, percolation of catch water drains into tunnel, bulging etc, should be detected & rectified.
*Al ventilation shafts should be clear of any obstruction and vegetation.
* The level & alignment of track & its approaches are to be checked and rectified.
* The level pillars & reference marks should be checked periodically.

SUMMARY:-
The huge money spent in construction of railway track is a waste, if the track is not maintained properly for comfortable, safe, fast & economic movement of trains over it. Maintaining of track, bridges, points & crossings, tunnels, level crossings etc involves a huge amount of work, employing millions of workers. It should be done efficiently for safety of passengers & goods. The use of mechanical appliances should be encouraged, wherever possible in maintenance operation. 

1 comment: