Thornton Tomasetti, a New York-based engineering firm with offices in Portland, is merging with Weidlinger Associates.

The combined companies will have 1,200 employees and locations in 34 cities. Terms of the deal were not disclosed.

In 2012, Thornton Tomasetti acquired Fore Solutions, a Portland sustainable-building consultancy founded by Gunnar Hubbard, who became head of Tomasetti’s Building Sustainability practice. Fore Solutions designed some landmark LEED-certified buildings in Maine, including the Hannaford store in Augusta and the Borsage family education center at Coastal Maine Botanical Gardens in Boothbay, both of which received platinum certification.

Thornton Tomasetti has also worked the Village Centre housing project in Brewer and Avesta Housing’s Pearl Place I and II in Portland.

Weidlinger Associates, which is based in New York City, was the structural engineer for the Wishcamper Center at the University of Southern Maine; structural consultant for the Portland International Jetport’s car rental facility; and did studies of the terminal buildings and parking areas at Bangor International Airport and of the cable systems for the Waldo-Hancock Bridge.

The new firm will operate under the Thornton Tomasetti name.