New contracts and extensions for Thames Water, the Hinkley Point C nuclear power station and additional contracts for Crossrail in London meant the order book was worth £3bn (2012: £2.4bn) at end December, of which 90% was repeat work. More than £750mln of the work is for 2014.
Costain added it also had preferred bidder position on contracts worth over £400mln with tendering activity also high.
The last two months of 2013 had also been busy, it said, and full-year results will be in line with company expectations.
The group realised £9.1mln profit from the sale of its minority shareholdings in three joint venture companies to Severn Trent just before the year end and has taken just bought Serco’s 27% interest in their motorway technology joint venture for £2.4 mln.
Andrew Wyllie, chief executive, said: "We are delighted to finish the year with a very strong order book.
“Our continued success is the direct result of our focus on delivering innovative engineering solutions for blue chip customers who are investing in meeting national needs."