Engineering plans for HS2 Old Oak Common station revealed
The sheer size and scale of the operation to build the Old Oak Common High Speed 2 (HS2) station has emerged in an exclusive interview with HS2 Ltd project director S4 Old Oak Common Matthew Botelle.
The HS2 station at Old Oak Common will be the last stop before the
£56bn high speed rail line terminates 6km to the east at Euston, in central
London. Passengers using HS2 phase 1 route between London and Birmingham will
be able to disembark at Old Oak Common and interchange with Crossrail’s
Elizabeth line and the Great Western Railway (GWR). The station will have a
capacity for around 100M passengers, rivalling Waterloo Station in Central
London.
Trains from the east will arrive at underground
platforms from the Euston tunnels section and head north via the Northolt
tunnels.
Each of the six new platforms for the high speed line will be 400m
long. To accommodate the switchings and crossings at either end of the
platforms, the station will include a huge underground box spanning the length
of the tracks. This will be a total of 903m long, 70m wide and 15m high in the
west to 22.5m high in the east.
“It’s one the biggest structural boxes in the world,” said
Botelle. “Certainly nothing will be built on this scale ever again in
Britain,” he added.
The sheer size and scale of the operation to build the Old Oak
Common High Speed 2 (HS2) station has emerged in an exclusive interview with
HS2 Ltd project director S4 Old Oak Common Matthew Botelle.
The HS2 station at Old Oak Common will be the last stop before the
£56bn high speed rail line terminates 6km to the east at Euston, in central
London. Passengers using HS2 phase 1 route between London and Birmingham will
be able to disembark at Old Oak Common and interchange with Crossrail’s
Elizabeth line and the Great Western Railway (GWR). The station will have a
capacity for around 100M passengers, rivalling Waterloo Station in Central
London.
Trains from the east will arrive at underground platforms from the
Euston tunnels section and head north via the Northolt tunnels.
Each of the six new platforms for the high speed line will be 400m
long. To accommodate the switchings and crossings at either end of the
platforms, the station will include a huge underground box spanning the length
of the tracks. This will be a total of 903m long, 70m wide and 15m high in the
west to 22.5m high in the east.
“It’s one the biggest structural boxes in the world,” said
Botelle. “Certainly nothing will be built on this scale ever again in
Britain,” he added.
From the HS2 platforms around 16m underground, passengers will
ascend to a 150m by 70m by 21m concourse in the surface level station. This
will then link through to the adjacent Elizabeth line and GWR station and
platforms.
Consultant WSP will design the £1.3bn station with
a decision on the contractor to build it due in the Autumn.
Although the structure of the underground box is relatively
simple, work will be complicated by the logistical challenges of the
constrained site, the sheer volume of material to be removed and the interface
between the three different lines, said Botelle.
Around 1M.m3 of material from the box and 2M.m3 of
material from the tunnels on either side will have to be removed from the site,
he said.
“It’s a logistics challenge,” he said “It’s essential we get the
excavated material out by rail and conveyers, so that’s why it’s essential the
strategy gets nailed down as soon as possible.”
To add to the challenge, the ground at the site is contaminated
resulting from 103 years of industrial use. As a result it will have to
undergo a major remediation programme.
There will also only be one entrance and exit to site via the
south west corner, through a GWR rail depot. This is currently being
decommissioned to make way for the new stations.
Botelle said first works will incude widening and adjusting the
alignment and the size of the access road so trucks and the demolition
equipment can get onto the site.
Plans are for the station box to be constructed with diaphragm
walls around its perimeter, and a large concrete and bentonite slurry plant
will be located on the site.
The sub-surface HS2 station will also be mechanically ventilated,
allowing a much taller adjacent site development to be built.
“If you build above a certain level on the surrounding plot of land, you get dead air over the box because of the prevailing wind direction,” Botelle explained. “If you mechanically ventilate the box, you’re not affected by cross winds and you can build higher buildings on the adjacent plots.”
To allow the new stations to be built, the decommissioning of the
GWR and adjacent Heathrow Express depot is being carried out in four phases. As
these are completed, more land will be released to HS2 for track, platform and
and station construction.
Phase one included the removal the tracks serving the depot from
the main Network Rail signalling system. The data transfer was completed at
Christmas last year and this stage has now been completed.
Phases two and three, are due for completion in summer this year
and next year. These include demolition of the Heathrow Express depot, allowing
the HS2 station and interface building to be built. In phase four, planned for
completion in 2020, the adjacent Heathrow Express depot will be demolished
making way for the Elizabeth Line and GWR tracks and platforms.
Phase four works is directly to the north of the existing GWR tracks,
so to save time and ease construction, six out of the eight platforms for the
Elizabeth line and GWR will be built off site and lifted into place during
possessions. The remaining two platforms which are directly adjacent to the
existing GWR tracks will then be constructed in a more complex, staged
sequence.
Despite the Elizabeth line opening at the end of this year, trains
will not stop Old Oak Common station until it opens in 2026. Botelle wants the
station to set standards for design with big, light, open spaces, excellent way
finding and prominent lifts and escalators, making it easier for passengers
with luggage to move around.
4 April 2018