Methods for Correction of Creep
There are two methods used for the correction of creep. These are
- Pulling back Method
- Use of Creep Anchors / Anti Creepers
1. Pulling Back Method
In pulling back method the effects of creep are observed during ordinary maintenance of track. Then the rails are pulled back equal to the amount of creep, either by manpower or by the use of jacks. For this purpose, the sleeper fittings are made loose, the fish bolts at one end of the rail are removed while at the other end they are made loose. The liner of required size is interested in the gap and the rails are pushed or pulled as required.
Pushing is done by inserting short length of rod through bolt hole and then pushing the rail forward by means of a crow bar. Pulling is done by inserting hook through the bolt hole and then hauling the bolt hole by means of a rope attained to it.
Following points should be kept in mind in correction of creep
- The track below sleepers should be properly packed after pulling and pushing operations.
- The small pieces of rails should always be kept ready during progress of work to allow passage of trains at low restricted speeds.
- The number of labours required depend upon the nature of creep, number of sleepers affected due to creep.
- All the fish bolts should be removed, cleaned and oiled and then refixed and tightened up after the rails are brought to their proper positions by pushing or pulling.
- The anchors, if to be installed, should be fixed after this process.
2. Use of Creep Anchors OR Anti Creepers
In this method, specially constructed device known as creep anchors or anti creepers are used. It consists of cast iron pieces used to grip the rails. Creep anchors are provided behind the sleepers for every third or fourth sleepers.
This arrangement prevents the movement of rails because the sleepers which are embedded in the ballast will also have to move if the creep has to take place. This method of reducing creep is quite efficient and economical as it reduces the cost to the extent of about 75% to that of pulling back method.
Various types and makes of patented creep anchors have been constructed and are in use and most of them are found considerably effective.
The following points should be kept in mind in case of creep anchors
- The creep anchors should be strong enough to resist the stresses produced due to creep.
- The number of creep anchors per rail length should be determined by intensity of creep.
- The creep anchors should be provided at a place where creep originates and not alone where the results of creep anchors are most apparent.
- It should be remembered that the creep anchors should not be provided over railway bridges as far as possible. It is better to provide sufficient number of creep anchors to arrest the creep before it reaches a bridge.