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Our People

Grant McCullagh

Director, Thornton Tomasetti & Managing Director, TTWiiN


Grant McCullagh is a Thornton Tomasetti Director and the Managing Director of TTWiiN. Grant has served on a number of public and private company boards, including Weidlinger Associates, which merged with Thornton Tomasetti in 2015. Grant combines an A/E technical and operations background with a deep understanding of corporate finance. He has considerable management experience, having served as a senior executive for a Fortune 500 firm, global engineering and construction companies and entrepreneurial startups as well as an operating partner at several global private equity firms active in the engineering and construction industries. He has worked across numerous industry sectors including complex facilities, transportation, water, environmental and government services.


MBA, Finance, University of Chicago

M.S., Architecture, University of Pennsylvania

B.A., Architecture, University of Illinois at Urbana-Champaign

Best-in-class market expertise, diversification and critical mass help drive companies to real success. Grant believes our firm has all of the attributes for achieving solid growth and innovation.