Murray said he felt he needed a change of direction after leaving Railtrack, but added that working for it was "the most amazing experience".
The move to Osborne is an example of a gamekeeper turning poacher. While at Railtrack, Murray acquired a reputation among contractors as an extremely tough negotiator. He was also instrumental in drafting Sir John Egan's Rethinking Construction report of 1998.
Murray joins at a promising time for the company – the firm last week posted a record pre-tax profit of £4m for the past year. Turnover stood at £182m, boosted by the firm's work in the public sector.
He said: "What attracted me was the company itself. It's a really sound company with a very strong sense of direction. Becoming chairman gives me the opportunity to get involved in the business."
Since leaving Railtrack, Murray has started his own consultancy, which offers procurement advice to clients and corporate strategy advice to contractors.
He has also joined the board of Manchester Airport and Ascot racecourse, which is redeveloping its facilities.
Murray started his career in construction at consultant Arup before joining airports operator BAA, where he became head of technical services.