Costain and May Gurney have announced merger plans.
The companies will have combined revenues of £1.6 billion and challenge rivals including Balfour Beatty and Carillion.
Major infrastructure contractor Costain, which is working on London's Crossrail underground rail tunnel, is based in Maidenhead, which will be the group's headquarters.
The group plans to retain May Gurney's headquarters in Trowse, Norwich, as a shared services base.
May Gurney has around 800 of its workforce in Norfolk.
More top news
MK Dons got one over their bitter rivals as they ran out 2-0 winners at AFC Wimbledon.
Cloud will thicken overnight with light and patchy rain for a time.
Northamptonshire Police is shaking things up in a bid to get more officers back on the frontline.