According to EDAW, whose London office is headed up by CABE commissioner Jason Prior, the merger combines EDAW's 'front-end planning expertise' with AECOM's management capabilities.
AECOM is 20 times the size of EDAW. It has 22,000 employees compared to EDAW's 1,200, and a turnover of US$2.5 billion (£1.4 billion) compared to the architect and planner's US$150 million (£87 million).
EDAW president Joe Brown said: 'This is an ideal marriage. EDAW's service offerings - particularly in urban regeneration - are a natural fit with AECOM's transportation, environmental and facilities strengths.'
AECOM president and chief executive officer John Dionisio said: 'The merger with EDAW will advance our strategic objective of broadening and diversifying our technical services, particularly in front-end planning and consulting.'