A new station is nearing completion at Paddington, west London, serving the Elizabeth Line (formerly known as Crossrail). Ramboll engineers have played an integral part in the delivery of the new station and the surrounding area
Meeting London’s 21st Century transport needs
The Elizabeth line will change the way people travel across London. It will carry an estimated 200m passengers a year, connecting Reading and Heathrow in the west with Shenfield in Essex and Abbey Wood to the south east of London, over 100km of new track and 21km twin bore tunnels under the central London section. When completed the new line will boost central London’s rail capacity by 10 per cent, bringing an additional 1.5m people within 45 minutes’ commute of central London. The Crossrail project has been the largest infrastructure project in Europe and Paddington station will be one of the jewels on the line.
Although appended to Isambard Kingdom Brunel’s 1838 terminus at Paddington, the new station will sit beneath the southern fringe original station, beneath Eastbourne Terrace and Departures Road. It will be one of 10 new stations, with a further 27 station upgrades required. The two new Crossrail platforms measure 260 metres long (more than double the length of the average tube station platform) and lie 23m below the surface. The Crossrail project is scheduled to finish in Autumn 2019.
A unique station in a historic context
The emerging project is hugely complex with a plethora of historic buildings and underground infrastructure. Brunel’s Paddington station is a Grade 1 listed building requiring sensitivity on all works around to the original structure, along with careful management of stakeholder’s requirements and design interfaces. MacMillan House and the Hilton Hotel which run along Departures Road are also Grade 1 listed, while the historic Osbourne Tunnel (once a postal route) passes under the Western end of Departures Road, adjacent to Network Rail plant rooms. Managing these historic complexities required sensitivity and, working closely with WSP and Weston Williamson architects as part of the Costain-Skanska Design & Build (CSJV) team, we married the new station with the surrounding area.
The Crossrail station box was constructed using the top-down technique, where the station was dug out from the surface (as opposed to tunnel boring). While this allows a much larger subterranean station than would have been possible using traditional techniques, it created additional challenges in such a constrained and highly developed urban location.
Eastbourne Terrace and Departures Road were formerly used as a minor bus terminal and taxi rank. Ramboll incorporated a two-phased design of the urban and public realm areas, which enabled the partial reopening of Eastbourne Terrace after two years. This approach required careful management of relationships with Westminster City Council (WCC), facilitating key discussions with Network Rail (NR), Transport for London (TfL) and local stakeholders.
The station entrance, canopy and facades
The main entrance to the station is illuminated and protected by a vast glass canopy, 120m long by 23m wide, incorporating the Spencer Finch art installation, ‘Cloud Index’. With the installation creating a picture of the sky that changes according to the light, the position of the sun and the time of day, the canopy will allow natural light to flood the station down to the open platform level. The size of the canopy, exacting client specifications and the sensitive interface with the Grade 1 listed station, all required careful detailing, construction sequencing and coordination with architecture, electrical services and drainage. Ramboll developed the structural detailed design brief with CSJV and Crossrail and took a leading role in the RIBA Stage E detailed design process, helping to achieve the client vision of a crisp structural form.
The Crossrail station incorporates high quality cladding finishes throughout, using multiple materials including aluminium, bronze, stone, glass, brick-slip and glass fibre reinforced concrete (GFRC). Ramboll facades team developed design intents for the various cladding support systems to meet the challenging site-specific loading and interface requirements and enable the appointed cladding specialist sub-contractors to understand the constraints and complete the detailed designs.
Managing flood risk
Ramboll has responsibility for assessing all below-ground surface water drainage for the station and we have undertaken a Flood Risk Appraisal for the site; designing and implementing solutions to mitigate risk. The site has been designed with positive drainage systems, which provide storm water attenuation to accommodate a 1:100 year storm (plus 30% allowance for the future effects of climate change). A key feature is the attenuation tanks which are high capacity drainage channels and oversized sub-surface storage units installed beneath trafficked areas. This has been integrated around both existing MacMillan House structures and new foundations while keeping all networks gravity driven.
Urban and public realm design
Public safety was critical to the design of both the station and the surrounding public and urban space. We have responsibility for detailed design of the highways and drainage of a 500m long urban and public realm scheme for Westminster City Council and Network Rail, thought to be the largest scheme currently under development for WCC. The scheme covers the length of Eastbourne Terrace and the adjoining Grade 1 listed buildings, and required support towards planning approvals from Historic England and other stakeholders such as Thames Water, Network Rail and Westminster City Council.
Our 3D shared modelling capability was critical to incorporating the design elements within a constrained and complex area, scattered with existing sub-structures, hydraulic and static bollards, benches and other urban realm furniture. These features wind around the main station box public entrance and the two large vent shaft head houses at either end of the site. Progressing the client’s scheme design through to final urban realm design, we accommodated stakeholders’ requirements and incorporated updates to the design as final details of buried historic structures were uncovered.
The first Elizabeth Line trains are expected to run through Paddington station in Autumn 2019. Passengers will experience a bright open station with a vast glass canopy allowing natural mood light to flood in. The surrounding area will benefit from a new expanse of public realm space allowing safe, easy access to and from the station. It will be the result of extensive collaboration between Crossrail, NR, WCC, TfL, Costain-Skanska, WSP, Weston Williamson Architects, numerous specialist sub-contractors and Ramboll’s experienced multi-disciplinary engineering team.