The forward orders have grown by £200m in the past four months thanks to deals like a £250m contract from Network Rail to deliver Crossrail infrastructure and stations between Stratford and Shenfield.
Costain shareholders will hear at the company’s annual general meeting today that the company continues to perform in line with the board's expectations.
Other deals secured since the start of the year include places on Network Rail’s £2bn seven-year National Electrification Programme and National Grid’s electricity and gas transmission frameworks.
Some £900m of the forward orders are for 2014.
“Costain is well positioned in a developing market of a limited number of providers who can deliver the innovative integrated consulting, project delivery and operations and maintenance services increasingly demanded by major customers<” the company said. “With increased financial resources, a record order book and a strong pipeline of opportunities, the board remains confident of meeting its expectations in 2014.”