The deal will see the combined company employ 95,000 people across 150 countries.

Michael S. Burke, AECOM president and chief executive officer, said: “This combination creates an industry leader with the ability to deliver more capabilities from a broad global platform to reach more clients in more industry end markets.

“Clients, employees and stockholders of both companies will benefit from the opportunities created by these expanded capabilities, broad global reach in key growth markets and economies of scale.

“In one step, we will dramatically accelerate our strategy of creating an integrated delivery platform with superior capabilities to design, build, finance and operate infrastructure assets around the world.”

Martin M. Koffel, chairman and chief executive officer of URS, added: “This is a compelling strategic combination that we believe will benefit our clients, stockholders and employees.

“Our two businesses are complementary, and our cultures are highly compatible.  We anticipate that employees from the combined company will benefit as the organization integrates its leadership talent and capitalizes on its greater scale to invest in its people, improve their career opportunities and advance their capacity to compete globally.”

AECOM said it expects “annual cost synergies”  of £146m which it expects to achieve by the end of the 2016 financial year.

The transaction is expected to be completed in October 2014.