Morgan Sindall, Costain and Hochtief have secured a 15-year deal at the Sellafield nuclear clean-up site.
The trio will work on the site's essential services, including power, water, transport and security systems, as part of the new Infrastructure Delivery Partnership (IDP).
The firms will be responsible for detailed design, procurement, construction, commissioning and handover, supporting Sellafield's nuclear decommissioning and waste management work.
The new partnership replaces the previous Infrastructure Strategic Alliance and is part of Sellafield's long-term acquisition strategy.
The nine-year deal, with the option of a further six years, takes it to 2040.
Author's summary: Trio wins £2.9bn deal for Sellafield infrastructure.