Rail Level and Setting Distance

Structure Erection Drawings (SEDs) show setting distance or implantation of the OHE masts i.e., distance of the nearest part of mast from the centre line of the nearest track as well as the height of the contact wire from rail level at each location. These are with reference to alignment and level of the track at the time of erection of OHE. Before electrification work is taken up, it should be ensured that the track alignment and level are finalized. This is particularly so in the case of yards under remodelling.

Any change in alignment due to slewing of tracks will affect the setting distance and consequently the stagger of the contact wire. At locations where the setting is critical i.e., close to the minimum permissible value, slewing of track may result in infringement of the moving dimensions with consequent danger of accidents. Change in rail level due to variation in ballast cushion or packing up or packing down of the track will also result in change in contact wire height. Though provision exists in the cantilever assembly for adjustments of the stagger and height, such adjustments are not to be made unless absolutely necessary. It is best to maintain the position of OHE and tracks as in the SEDs.

Alteration to track

"Before any alteration to alignment or level of electrified track is commenced, due notice shall be given to those responsible for the overhead equipment so that the overhead equipment may be adjusted to conform to the new conditions"

It follows, therefore, that any alterations of the alignment of the track on electrified sections shall only be made with the prior knowledge and concurrence of the Sr. DEE (TrD), so that he may arrange to correct the SEDs to the extent required. No alterations to the track affecting OHE parameters may be carried out without obtaining specific approval from Sr. DEE/TrD. Whenever any permanent changes are effected, the SEDs should be revised and a note made of the circumstances and the authority under which the revision has been made.

To facilitate periodical checking, rail level and setting distance should be painted at the base of each OHE mast face soon after commissioning, preferably in black letters. A horizontal line would indicate the rail level. The setting should be marked in correct to the second decimal place. Repainting of the these markings will ordinarily be required once in two years. Where pollution due to brake shoe dust etc. is severe, repainting may be required more often.

During yearly maintenance of OHE, rail level and setting distance should be checked and compared with the original figures. Any variations above 30mm in setting distance and 20mm in rail level should be advised to the PWI for correction. No change in setting distance and rail level should be allowed if such change results in infringement of moving dimensions.

It is essential to have a joint annual check of rail level and setting distance by the Chargeman /OHE and APW1.

In addition to the markings on the masts, a register should be maintained by CTFO (OHE) to record the annual measurements of implantation at critical locations over his jurisdiction. A similar register should be maintained by each Chargeman for his own section (see proforma 03-8 in Section-V).

OHE review