The boards of directors of both companies unanimously approved the deal, which calls for Washington Group stockholders to receive $43.80 in cash and .772 shares of URS stock for each Washington Group share.
"URS has a history of anticipating change in the industry, and this transaction is the next logical step in building for future growth," URS chief executive Martin Koffel said in a prepared statement.
The deal combines two of the nation's largest engineering and construction firms. URS has 29,500 employees in 20 countries, while Washington Group has 25,000 employees worldwide.
Washington Group is the parent company of Washington Savannah River Co., which operates the Savannah River Site in Aiken.