Although the majority of people arriving at Paddington’s deep underground Elizabeth line station will take the escalators up and out, a small number will take a set of escalators that go down even deeper underground.
The original Crossrail Act in 2008 authorised the construction of a shallow tunnel under Paddington mainline station to link the Elizabeth and Bakerloo lines, but in 2014, this was radically changed to a deep level tunnel, requiring a special authority to deviate from the approved plans.
The main reason for going deep was that subsequent surveys found a risk that subsidence would affect the Grade 1 listed Brunel Train Shed and there would be too much disruption of Network Rail operations and passenger flows on the concourse, and critically due to the residual risk of the collapse of the tunnel face and consequential risk to construction workers and the travelling public.
Essentially, passengers waiting for trains at Paddington station could have found themselves falling into the shallow tunnel being dug underneath them.
So, in 2014, the plans were changed to a deep tunnel.
The £40 million contract was eventually awarded to Costain Skanska Joint Venture (CSJV), who were already building the Elizabeth line station at Paddington. However, to avoid interfering with the new station build, they were able to make use of the empty Royal Mail building close to the Bakerloo line platforms for their base of operations and tunnel across to the Elizabeth line from that side of the station.
What’s been built is a long tunnel, with two sets of escalators, a lift and stairs at either end. As the tunnel is quite long, there are a couple of recessed niches along the route with seating in them should they be needed.
At the Elizabeth line end, the lift and escalators are next to each other, although to fit both in at the Bakerloo line end required the lift to be down a second side tunnel that then brings it up in the main concourse between the two tube platforms. The escalator shaft was squeezed in between the two tube line platforms a bit further down the platform.
It’s estimated that around 11.5 million people a year will use the new tunnel, so it’s going to be quite useful.
It also means that, via a convoluted route, the Bakerloo line platforms are now step-free, as they can use the lifts at the Elizabeth line end to get up to street level. There is however an unrelated project under construction at the moment that will see a lift shaft go direct from the Bakerloo line platforms to street level.