Crossrail Surface Works: Stockley Flyover (Interim)

Crossrail Surface Works: Stockley Flyover

CEEQUAL Excellent (86%) – Interim Client & Design Award
Version 4, June 2013 | London, England, UK

Client: Network Rail / Crossrail Ltd
Design: Jacobs
Construction: Carillion

Assessors: Lee Heffernan (Network Rail), Mason Baker (Jacobs)

Project summary

Stockley Flyover is a £90 million Crossrail project that is being delivered by Network Rail. The objective is to construct a new flyover to facilitate Crossrail and Heathrow Express services between London and Heathrow Airport, whilst allowing trains to Reading and beyond to pass through the junction unhindered.

The works are part of the Crossrail project and are therefore consented under the Crossrail Act and governed by the Construction Code including the Environmental Minimum Requirements.

Network Rail is responsible for the design, development and delivery of the parts of Crossrail that are on the existing rail network. This covers 70km of track and 27 stations, from Maidenhead in the west to Abbey Wood and Shenfield in the east. Both Network Rail and Crossrail Ltd were keen to implement CEEQUAL from the very start of the project. At Stockley Flyover the Designer Jacobs and Principal Contractor, Carillion, have fully committed to implementing CEEQUAL, helping to achieve such a high Interim Assessment score.

The Crossrail Act and Environmental Minimum Requirements already raise the bar in terms of environmental performance. CEEQUAL was the ideal driver to improve performance further, as well as provide a way of capturing and publicising our green credentials.


One of the key challenges at Stockley Flyover is the abundance of wildlife on site, particularly where the existing Heathrow Airport embankment was to be widened. As encouraged by the CEEQUAL process, the design sought to minimise the ecological impact. However, some loss of habitat, designated as a site of borough importance for nature, was unavoidable.


A major aspect of the early works was to fully assess and then translocate wildlife to suitable receptor sites. This involved the following:

  • An environmental site walkover
  • Detailed environmental surveys including phase one habitat surveys
  • Detailed species surveys and relocation plans
  • Tree protection surveys & plans
  • Compensation and restoration plans.

The translocation programme resulted in 46 slow worms, 593 smooth newts and 599 fish being moved to suitable nearby receptor sites. The catch of the day was a European Eel, a critically endangered species that was 5lbs in weight and over a metre long! Finally 30 wild orchids were relocated to a similar habitat in north London at the Maple Lodge Nature Reserve courtesy of the Maple Lodge Conservation Society. Follow up ecological surveys will take place at the translocation sites to monitor the success of the programme.

No net loss

The project is going beyond protecting wildlife from harm through translocation by implementing a biodiversity target of ‘No Net Loss’. This target was agreed by the Directors and indicates the high level of support and importance environmental management and biodiversity carries on the programme. The programme is working with Natural England to implement the Defra biodiversity offsetting methodology to ensure that it quantifies, tracks and reports biodiversity accurately.

For Stockley Flyover the ‘No Net Loss’ target means the creation of an entirely new compensatory pond at a nearby site know as The Piggeries, on Network Rail land. The pond will be groundwater fed and include a range of depths, slopes and associated planting, to maximise its biodiversity potential.

How did CEEQUAL influence your project?

The CEEQUAL tool allowed us to see where we have done well during the design stage and early works, such as our management of landscape, biodiversity and community relations issues. One of the benefits to the project of recently completing the CEEQUAL Interim Assessment is that it has helped us to focus our efforts during the main works on areas where we can improve our environmental performance, and hence CEEQUAL score, such as around our management of energy and carbon.

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