It’s January, and while lots of people have heard about the City Loop closure, less well-publicised are the shutdowns on the Hurstbridge, Alamein, Cranbourne/Pakenham and Frankston lines… plus more lines in the evenings.
Anyway, here’s something related – an expansion of a comment answer I left on a recent post.
The question was about how skyrail can be built while trains continue to run underneath. I thought I’d share a few photos from during the Dandenong line construction around Carnegie-Murrumbeena.
They had a bit of space to play with – not enough to do four tracks without land acquisition, but enough to build the two elevated tracks with gaps for water and sunlight to reach the grass and plantings in the public space below the new line.
It also meant they could keep trains running during much of the construction.
Early on they replaced the overhead stanchions with a special design:
The lower height at the sides allowed the new track structure to be put in place. The old station platforms had to be narrowed, but were mostly able to keep operating.
The new elevated island platform was built above the old tracks, at a higher level than the new tracks.
For much of the distance between stations, the new tracks and their support structures were built on either side of the old ones.
Once the new structure was completely in place, trains could run on it, while the old track and overhead structures were removed, and landscaping took place.
It was a bit different in the Noble Park section. The rail corridor there was wider, allowing them to build the new tracks next to the old ones rather than above them.
At Clayton as well, the new structure was built alongside the old rail line and station.
Overall the main part of skyrail construction probably took longer to build than the rail under (trenches) elsewhere on the network. But rail under requires a lot more preparatory work to move underground services first, so the big 6+ week rail shutdown is often accompanied by lots of smaller shutdowns.
In contrast, during most of the skyrail construction, trains were able to keep running. The main periods of no trains running was during construction of the ramps to carry trains to and from the elevated sections, which necessitated removal of the old track.
As I said in the earlier post, each method has pros and cons, and what works in one location might not work in another.
It’s not perfect – and much of the Cranbourne/Pakenham line is about to close again for several weeks for other upgrades, principally the rationalisation at Caulfield junction, and signalling work.
But there’s clearly a benefit from keeping trains running as much as possible during construction, and skyrail can help with that.