[2] Immediately after graduation, Holland began his career in New York City working as an assistant engineer on the construction of the Joralemon Street Tunnel.

[7] Holland was the first chief engineer on the Hudson River Vehicular Tunnel project, earning an annual salary of $10,000.

[6] Holland designed four ventilation shafts that would bring 3,500,000 cubic feet (99,000 m3) of fresh air into the tunnel every minute.

[6] Construction on the tunnel began April 1, 1922, when Holland ceremoniously drove a pick into the ground at Canal and West streets in Manhattan.

[9] The stress and long hours working on the tunnel project caused him to have a nervous breakdown, and he went to a sanatorium in Battle Creek, Michigan, in order to recover.