Thread by @NetworkRailSE

1/ We are in the final days of a major project to rebuild the complex and busy Lewisham Junction, #London

This thread will look at the various stages of work over the past 8 days, and why the project is important for @Se_Railway passengers.

2/ In the early stages of any track or junction replacement, after disconnecting power and signalling, we rip out the old rail, sleepers, and ballast.

The vast majority of the old materials will be recycled.

3/ Special matting and new ballast are laid to form the new track bed.

We used more than 6,300 tonnes of new ballast for this job.

But, why is the track bed so important?

4/ The railway signalling, power supply, rails etc. are only as good as the track bed they sit on.

Wet beds, when the ballast falls away can cause track instability; leading to signalling, comms, and power supply faults.

This has been a big problem at #Lewisham - up to now!

5/ Once the track bed is laid it’s time to install the rails and sleepers.

Panels are prepared off-site, brought in via engineering trains and then lifted into place by this Kirow crane.

81 panels were lifted in at Lewisham, the heaviest weighing 28 tonnes!

6/ It's like a massive jigsaw puzzle!

And while the pieces are very big and very heavy, we need to be very precise.

We work to millimetres, as any discrepancies with the track alignment (gauging) could in a worst case scenario cause a train to derail.

7/ When the pieces of the puzzle are in it is time to connect them all up. Multiple teams of welders have been working on 200 welds in total.

Their work will ensure trains can travel smoothly over the junction, and people living close by will hear less noise.

8/ When the rails, signalling, power supply and other components are reconnected it is time to tamp.

Tamping is the railway equivalent of fluffing a pillow.

Again, it's about ensuring we have a stable and smooth track bed for the reasons given above.

9/ @Se_Railway passengers will be all too aware of how any incident at #Lewisham can lead to congestion and delays rippling across the entire network.

This work is another step towards making this section of railway more reliable.

Thanks for your patience while we worked🙏.

Thanks to Sam and his colleagues @ColasRailUK for sharing the pictures from site.