The company said it was confident that Labour's commitment to PPP would send its full year figures towards a pre-tax profit of £53m.
Chief executive Brian Staples said: "There has been a marked upturn in the flow of public sector bids since the election and we expect that situation to accelerate."
There’s been an upturn in public sector bids, and we expect that to accelerate
Brian Staples, chief executive
The jump in profit came on the back of a rise in turnover of 33% to £397.6m. Much of the increase was a result of growth in the company's forward order book, which stands at a record £3.5bn.
Staples said more than £1.6bn of new work had been secured in the first half of the year. He added that the restructuring of the group to encompass Tubelines, the London Underground consortium, had resulted in its appointment as the preferred bidder for the Jubilee, Northern and Piccadilly lines.