More than £700m of revenues have been secured for 2014, and approximately £2.1bn of work is set to start in 2015 and beyond.
In addition, Costain has a strong preferred bidder position of more than £400m.
In a trading update, the board said that tendering activity across target markets remained high.
More than 90% of the order book is a target cost, cost reimbursable form of contract, Costain said.
Examples of work won this year to date include:
- An AMP6 programme for Thames Water
- Several contracts for Crossrail including for the railway systems
- A contract with EDF for the water cooling systems for the Hinkley Point C new nuclear power station.