Transformation of east London, which began with the London 2012 Olympics, is continuing at pace with a station redevelopment scheme at Hackney Wick.
Project: Hackney Wick station redevelopment
Client: Network Rail (on behalf of London Legacy Development Corporation)
Project value: £25m
Design and build principal contractor: VolkerFitzpatrick
Lead designer: Mott MacDonald
Lead architect: Landolt + Brown
Located between the iconic sporting venues of Queen Elizabeth Olympic Park and the heaving summer festival location of Victoria Park is Hackney Wick London Overground station.
The immediate area is experiencing major housing and employment growth, so the station is undergoing a £25m overhaul to improve its accessibility and capacity while making it a more attractive feature of the local landscape.
The railway runs east-west on an embankment about 6 m above ground level and severs this part of Hackney Wick.
The existing elevated station is accessed via ramps from street level to both the north and south, with the current ticket office located on the north-side platform. It is accessed from the south-side platform via a footbridge (now demolished as part of the proposed works).
The project aims to modernise the station’s access and infrastructure, with new lifts and stairs to serve each side of the track.
The scheme also includes an upgraded public realm, a new station building and a ticket hall on the ground floor south of the track. The station building and ticket hall potentially form part of a future oversite development.
A north-south subway at street level will be introduced beneath the track, providing connectivity under the railway and effectively creating a new street. An architecturally striking glass screen will split the subway along its length to separate the publicly accessed pedestrian route from the portion that forms part of the station and can be accessed by ticket holders only.
“With the subway providing connectivity under the railway, the project is effectively creating a new street”
The surrounding area is seeing a shift from factories to residential and commercial workspaces, so it feels right that the outdated station gets to move with the times, too. It forms a key part of the masterplan to regenerate the area and provide a larger-capacity pedestrian connection between the north and south sides of Hackney Wick.
Mott MacDonald is working as part of a design-and-build team with principal contractor VolkerFitzpatrick and lead architect Landolt + Brown. Mott is carrying out the permanent multi-disciplinary engineering design – civils, structural, M&E, telecoms, permanent way, environmental and town planning.
Landolt + Brown has developed a highly place-specific design, the architecture influenced by the industrial character of the area and the River Lea 100 m east of the station, while integrating the proposed engineering structures.
Deciding how to build this subway has been one of the main engineering challenges of this project.
Initially, the aim was to build it using pipe-jacking technology so that the platforms, tracks and station infrastructure could remain in situ throughout the works. As the scheme evolved, however, a suitable blockade over the Easter 2017 weekend was identified and secured.
This will allow the entire embankment to be lowered to ground level, the subway driven into position and the embankment and railway reinstated on top so that trains can run immediately after the work is completed.
Mott MacDonald has worked in close partnership with VolkerFitzpatrick to develop this alternative scheme and to overcome the tight time constraints on the construction activities during the four-day blockade.
“The portal will be driven into position by self-propelled modular transport”
The blockade works will involve removing sections of track, platforms and soil down to a competent gravel layer before the subway can be installed. To optimise the amount of time required to backfill the embankment, VolkerFitzpatrick proposed the use of lightweight polystyrene blocks to replace a proportion of backfill. This will significantly reduce the amount of soil compaction required.
The subway’s internal dimensions are 12.7 m wide and 22.5 m long and it is a heavily reinforced concrete portal frame structure which is currently being prefabricated to the north of the site (pictured).
As the portal will be driven into position by self-propelled modular transport, the weight of the structure needed to be managed to ensure that it was within the hydraulic capabilities of the SPMT and also the allowable bearing pressures of the ground beneath its wheels.
At the end of the four-day Easter blockade, the railway will be operational and the station facilities will be running in a temporary state until permanent features are built either behind hoardings or during subsequent railway possessions.
Sarah McCarthy is a senior engineer in Mott MacDonald’s metros and civils (bridges) team