Murphy is now on site with the job due to be finished by January 2011.
The civils specialist beat-off competition from six other framework contractors including Balfour Beatty, Carillion, Laing O’Rourke and Kier.
The scheme at Swanlea School will include utility diversions, the construction of a new substation and utility building, demolition of some existing structures and provision of a new access road to make way for the new Crossrail route.