A set of new tunnels being dug between the Bakerloo line platforms at Paddington have been successfully completed despite the challenging conditions they presented.
Excavating the new tunnels (c) Dr. Anmol / Bedi Consulting
The new tunnels are needed as they will be used to provide a connection to a new tube station entrance that is being included in the Paddington Cube, a new office block being built next to the mainline station. When it opens, there will be more escalators down to the Bakerloo line, and for the first time, direct lift access. The new entrance may also end up as a shortcut for people on that side of Paddington station to the Elizabeth line thanks to the deep tunnel linking the two lines.
Over the past year, behind hoardings on the Bakerloo line platforms, a new corridor linking the north and southbound platforms has been dug just underneath the existing escalator, and a side passage running between the platforms has been dug to link up with the new station entrance.
New tunnels in orange (c) Scott Brownrigg
All the tunnels were dug using hand-held mechanical diggers, and the soil was stabilised using sprayed concrete linings (SCL), and will later be fitted out for passenger use. According to Bedi Consulting, which was responsible for tunnel engineering consultancy, the project was challenging because of how close the new tunnel was to the bottom of the escalator shaft, and is thought to be the closest underpass of an SCL tunnel to an operational escalator for TfL to date.
They were also allowed soil movements of less than 2mm per metre of tunnel to prevent the escalator above from jamming if its mechanical workings were to slip.
Bedi Consulting said that “for such a small project, it’s been an immense challenge”, especially as the initial plans were to close of the escalator for several months during the closest tunnelling, but they were able to avoid that happening. On top of that, they also came across unexpected piles in the tunnel face when excavating, which needed to be designed around.
The tunnelling was carried out by Tunnelcraft.
When the new entrance opens, there will be a large entrance hall with two sets of escalators down to the ticket hall area, then the new set of double-escalators down to an intermediate floor just above the rail tunnels, then a short staircase down to the platforms. A lift from the new entrance will give step-free access from street to platform.
The design of the new station layout was carried out by Scott Brownrigg.
Cutting away the London Clay around the outside of the Bakerloo line tunnel rings (c) Dr. Anmol / Bedi Consulting
Joint with old Bakerloo line tunnel (c) Dr. Anmol / Bedi Consulting
Spraycrete lining the tunnels (c) Dr. Anmol / Bedi Consulting
I assume stopping the escalators would have meant closing access to the Bakerloo line completely? There’s barely capacity at peak times with them operating and it’s a long slog up
Probably close the platforms for a few months – as was done when the Elizabeth line tunnel was being dug.
Any timeline as to when it will open?
The rest of Paddington is looking really impressive so it’s good the access to the Bakerloo platforms is being improved as well.
Just curious as to how a 2mm allowance for soil movement is measured. Given a grain of soil isn’t much smaller. No doubt there must be a clever method!?
“They were also allowed soil movements of less than 2mm per metre of tunnel to prevent the escalator above from jamming”
Is there an “only” missing there?
Any reason why street level to Bakerloo line trains aren’t step free?
Currently it’s just Street to Platforms.
Any plans to remedy this?
Im presuming they’ll refurbish the Bakerloo line platforms too, or at least I hope they will. Its a stark contrast transitioning from the Elizabeth to Bakerloo lines.
It certainly is and rightly so. The age difference between the two is of course the main reason but a simple wash and brush~up of the Bakerloo line station would go a long way to rectify things.
This would magnify the effort put into design back then enabling it to outshine the new.
The minimalist world in which we have been living for æons now is beautiful in its simplicity and I’m not arguing for a return to the excessive gewgaws. But cost, ease of maintenance and no doubt Health and Safety rules have reigned supreme for so long that I think that we’ve forgotten to show the joy and pride in these grand projects.