 Haupt resigned his commission on September 30, 1835, to accept a job under Henry R Campbell as Assistant Engineer engaged in the surveys of the Allentown road and of the Norristown & Valley Railroad, which opened in 1835 and 15 years later merged into the Chester Valley railroad.At 19, he was appointed Assistant Engineer in the state service and located the line from Gettysburg to the Potomac across the South Mountain which is now a part of the Western Maryland.In 1839, Haupt designed and patented a novel bridge construction technique known as the Haupt Truss.