Various alternatives to the Harbour Tunnel were put forward including tunnels with different alignments, bridges across the Harbour at different points; a bored rail tunnel between North Sydney and Wynyard; a ninth lane on the Harbour Bridge; four new road lanes as a second deck on the Harbour Bridge and new bus lanes on the Harbour Bridge.

It was also argued that the provision of more public transport facilities would relieve congestion on the Bridge. A light rail system was proposed from the Northern beach suburbs to the city via North Sydney since much of the traffic crossing the Bridge originates in those Northern suburbs.

Opponents to the Tunnel argued that alternatives were not given adequate consideration once the Tunnel was proposed by Transfield-Kumagai and taken up by the Department of Main Roads and the Minister for Public Works.