URS Corp., one of the country's largest design and engineering firms, said it will acquire Los Angeles-based engineering and construction company Dames & Moore Group for about $300 million in cash in a deal that will create a global engineering giant. URS said it will pay $16 a share for Dames & Moore, or a 30% premium to Dames & Moore's closing price of $12.31 on the New York Stock Exchange. The acquisition was announced after the close of U.S. markets. URS also will assume about $300 million in debt in the deal. Dames & Moore designs light-rail systems and manages construction at New York's Kennedy Airport. San Francisco-based URS does planning, design and environmental projects such as waste water treatment plants and landfills. URS shares rose $1.44 to close at $23.50 on the NYSE.