Thierry graduated from the Ecole Nationale des Ponts et Chaussées in Paris and subsequently held various positions in the engineering and construction sectors. In 1994 he joined Egis Projects, a leading international project developer and operator and subsidiary of the French Caisse des Dépôts whose activities encompass the design, financing, construction and operation of facilities.

At Egis, Thierry was involved in the managing and financing of infrastructure projects all over the world prior to being appointed chief executive of Egis in 2001. He joined AECOM as a director in late 2004 to concentrate on developing and managing the Meridiam Project which was set up in 2005.