Tunnel eyes installed at Royal Oak Portal, September 2011 © Crossrail
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Excavation at Royal Oak Portal, May 2011 © Crossrail
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Tunnel eyes installed at Royal Oak Portal, September 2011 © Crossrail
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Installation of diaphragm wall rebar cage © Crossrail
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Custom built gantry crane, Royal Oak Portal © Crossrail
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The facts
Client:
Crossrail
Location: London
Services: Multidisciplinary
design for RIBA stage D, E & F for tunnel portals, including
structural, geotechnical, environmental and highway engineering,
architectural design and planning and consents
Sector: Transport
Contract Type: Framework
Start/Completion: 2009 -
ongoing
The project
Crossrail is the largest transport
scheme seen in London and the South East for 50 years, as well as
being the biggest construction project in Europe.
Designed to join the Great Western and Great
Eastern railway networks, the project comprises a 118km rail link
running from Maidenhead and Heathrow in the west out to Shenfield
and Abbey Wood in the east.
New stations, able to accommodate 200m trains,
will also be built at Paddington, Bond Street, Tottenham Court
Road, Farringdon, Liverpool Street, Whitechapel, Canary Wharf and
Woolwich. At the height of construction it is estimated that up to
14,000 people will be employed on the project through the supply
chain.
In 2008, a multidisciplinary Capita Symonds
team - including civils, architecture and M&E engineering – was
awarded a place on the Crossrail Design Framework to design the
project’s tunnels and portals.The company is designing the
following schemes:
Crossrail Royal Oak Portal
One of four portal contracts on the
Crossrail programme, the Royal Oak Portal lies to the west of
Paddington and provides a transition from the overground to the
underground sections of Crossrail. It is also a significant site as
Tunnel Boring Machines (TBM) on the Central West Tunnel sections
will be launched from this structure.
The site - which is constrained by its narrow
width and also by the clearances under the existing Lord Hill’s,
Ranelagh and Westbourne Bridges - is bounded by the Westbourne Park
Worksite (west), Paddington Goods Yard (east), A40 Westway / Harrow
Road (north) and the LU Hammersmith and City Line and Network Rail
Great Western mainlines (south).
The package of work was for the provision
of RIBA D, E, and F designs and all planning and environmental
consents for the portal. Specific design work includes:
- Tunnel portal structure;
- Propped, retained cut to the west of the
portal, including the barrel arch roof;
- Retained cut, taking the railway to
grade;
- Escape and intervention facilities at the
portal, including surface holding area;
- Plant rooms at the portal and associates
service routes;
- E&M services to provide the necessary
power, lighting, ventilation etc to support the operation of the
plant rooms and the escape and intervention facilities;
- Flood protection structures;
- Attenuation tank for surface water
discharge;
- Above ground structure for plant rooms and
escape;
- Access road and parking for emergency
vehicles;
- Relocation of Marcon Sewer;
- New foul and surface water connections;
- Provision of construction space to assemble
and operate TBMs for tunnel construction, including spoil removal
and segment delivery and storage.
The Royal Oak
Portal was the first of the five Crossrail portals to be completed
- ahead of schedule - in September 2011.
Crossrail North Woolwich and Plumstead Portals
The North Woolwich and
Plumstead portals are on the southeast section of the Crossrail
route which links central London with Abbey Wood. The portals
form the entrance of the Thames Tunnel section (2.6 km) which runs
under the River Thames from North Woolwich to
Plumstead.
The Plumstead Portal is the launch point for
TBMs - to create twin bore tunnels between Custom House and Abbey
Wood - which are recovered at North Woolwich. On completion of the
tunnel drives, the Plumstead portal will form the main entry point
from east London not only to the Thames Tunnel, but also to the
Central London drives for fit-out. The portal structures are
approximately 420m in length and consist of a retained cut; a cut
& cover section; mechanical and electrical plant rooms; and
emergency intervention and escape points.
East of Plumstead, Crossrail joins Network
Rail’s North Kent Line forming a four track railway to Abbey Wood.
The North Kent Line eastbound track will be diverted over the
portal roof to accommodate cross platform interchange at Abbey
Wood. Coordination of design and construction of Crossrail
sub-surface and Network Rail’s surface works will be key to the
success of this section of the project.
The package of work is for the provision of
RIBA D, E, and F designs and all planning and environmental
consents for the portals. Specific design work includes:
- Tunnel portal structure;
- Propped, retained cuts to the portal
ramps
- Retained cuts, taking the railway to
grade;
- Escape and intervention facilities at the
portals;
- Plant rooms at the portals and associates
service routes;
- Modularised plant containers in services
compound at North Woolwich
- Reinforced concrete building recessed into
existing railway embankment at Plumstead
- E&M services to provide the necessary
power, lighting, ventilation etc to support the operation of the
plant rooms and the escape and intervention facilities;
- Flood protection structures;
- Attenuation tanks for surface water
discharge;
- Free standing intervention and escape stairs
at North Woolwich, internal at Plumstead;
- Secure parking for maintenance vehicles;
- New foul and surface water connections to
sewers;
- Construction sequence planning to accommodate
TBM installation and recovery for tunnel construction, including
spoil removal and segment delivery and storage.