A Look at the Crossrail Tunnelling Portal at Royal Oak
Sandwiched between the Westway and the Hammersmith & City Line is Crossrail’s Royal Oak Portal – the point from which central section tunnelling will start in the west and the point at which trains will enter or leave the tunnelled section.
Construction of the Portal has now largely been completed, with tunnelling due to commence next year. At only 21m wide, its an incredibly narrow worksite and, as the photo below demonstrates, one that borders pretty much directly onto the live railway at various points.
For those familiar with this particular stretch of the Hammersmith & City, the site took over (amongst other things) the site formerly occupied by the old black cab park (complete with café and petrol pumps). All of that, and more, has long since disappeared beneath the site approach.
Advancing towards the Portal itself presents a rare opportunity to see Royal Oak from its northern side.
Hampden Street footbridge sits at the start of the 285m long ramp down to the Tunnel Eyes. This was raised during an Easter blockage to facilitate the works beneath it, and the evidence of that can be seen on the second photo below. It will, however, still need to be lifted twice once the TBMs are assembled, in order to allow them to pass beneath.
The area cleared for TBM assembly is also where the new turnback sidings will ultimately be located. This can be seen in the photo below. First Group’s buses will need to be moved off the rear of the site to Atlas Road until after construction is complete. These will ultimately return to new facilities on top of the sidings at the end of the project.
Interestingly – especially in the context of Kensington & Chelsea’s push for a Crossrail station at Royal Oak – talking to the contractors on site revealed that the siding platforms that featured on the original plans will now not be built. Unfortunately they were unable to confirm when this decision was made.
The Portal itself has elements of the Death Star trench about it when viewed from the surface. Approximately 100m of Sheet Pile Wall gives way to another 190m of D-Wall as the retained cutting gets deeper. Temporary props are still in place at the Tunnel Eye end, marking the point at which the evacuation stairway will eventually be sited.
Heading into the Portal itself, a base slab on which the trackbed will eventually be placed gently slopes down to the Tunnel Eyes. A number of Permanent Props are in place towards the end, strangely reminiscient of the Connaught Tunnel (although more utilitarian in design).
The Tunnel Eyes themselves have a diameter of 7.24m and sit in front of the tunnel head. It’s these the TBMs will use to drive off from when they begin tunnelling. Looking inside, they actually gently angle outwards, reflecting the fact that the twin tunnels will bow out slightly beneath Paddington.
Overall, its an interesting and compact site, but one that will shortly be a hive of activity. Once the TBMs arrive and tunnelling begins, we will endeavour to engineer a return – something that would likely produce a very different set of photos.