In recent weeks, we have been replacing insulated block joints. The existing joints were at the end of their service life, the insulating plastic sheathes around the plates brittle and cracking. Furthermore, the rail ends showed substantial 'lipping', with the insulators between them badly deteriorated.
For the uninitiated, an Insulated Block Joint (IBJ) is a specialised fishplate which insulates the two rails it connects. This allows for the separation of track circuits, an essential system for the detection and so signalling of trains.
We started the first day at a set of IBJs north of Asher Lane LC. The nuts put up a good fight, but with some penetrating fluid and good grunt they did eventually admit defeat and came free. We then cleaned up the mating surfaces on the joints and cut away and rail lipping.
However, due to the unexpected warmth of the day, the rails had expanded, making the insulated end posts impossibly stuck. Considering this problem, we made the decision to remove the remaining joints that day and replace them the following week.
The remaining two pairs of joints came apart in much the same way as the first, except for the joints on the curve leading up to Asher Lane LC. As they are on a tight corner, the securing bolts were under a great deal of tension. Like many problems in life this problem was solved with gentle persuasion: A 6ft spanner extension!
When we returned the following week, armed with every tool we could possible need. We encountered the opposite problem: the previous nights frost had caused the rails to contract some millimetres. We conceded we would have to wait for the sun to warm the rails.
Sure enough, the rails began to snug up to each other. Then the new IBJs went in fairly hassle free, barring some bolt size irregularities. We soon settled into a rhythm, with each member of the team doing a specific task. This allowed us to work through the two remaining joint pairs in quick succession.
