As Siemens’ construction partner, VolkerFitzpatrick is designing, constructing and commissioning the two depots over the next three years at Hornsey in north London and Three Bridges, near Crawley in West Sussex.

The deal is the biggest contract in the firm’s history and is understood to be worth around £150m.

This latest win comes on the back of two stabling yard projects secured for Crossrail at Acton and Ilford.

The Three Bridges depot, which is split into east and west-side facilities either side of the London to Brighton mainline, comprises a five road, 12-car, maintenance building. This depot is due for completion in 2015.

The Hornsey depot, which is expected to be completed in 2016, is being constructed within a live operational rail environment adjacent to the East Coast mainline and the existing Hornsey depot.

The project comprises the co-ordinated redevelopment of two separate areas of existing infrastructure, including the existing operational depot and the derelict sidings immediately to the north of the existing depot.

Richard Offord, managing director of VolkerFitzpatrick, said: “Our extensive experience in building state of the art rail maintenance depots, coupled with Siemens considerable experience in this area, makes for a dynamic and highly skilled integrated project team.

“The depots are being built with close regard to all stakeholders and communities, in a sustainable, safe and responsible manner. The sites are both registered with the Considerate Constructors Scheme.”