The firm rose through the rankings after its joint venture with Laing O’Rourke secured the £402m phase 2 of the East-West Rail project, according to information specialist Glenigan.
The design and build job will be delivered as a four-way alliance with Network Rail and Atkins, upgrading 58 miles of track, building a new station at Winslow, two new platforms at Bletchley, 18 overbridges, 22 footbridges or subways and changes to 97 railway crossings.
Among the other high fliers for the month, Bouygues also powered up the table after securing a £107m waste project in Belfast for the Full Circle Power consortium.
In Wales, Morgan Sindall took a £100m project to build an urban village in Cardiff for Tirion, while in the East Midlands, Winvic bagged a £76m job for Mountpark Logistics to build a distribution unit in Coalville.
Judged on the rolling 12-month haul of new work, Kier extended its lead over second placed Bouygues, now closely shadowed by Laing O’Rourke.
On civils work alone Balfour Beatty is keeping ahead of its nearest rival Costain after winning a big deal in Warwickshire.