The highway currently begins at a grade separated intersection with SH 74 on the northern approach to the Lyttelton road tunnel. It travels east to west through suburban Christchurch via Port Hills Road, Opawa Road and Brougham Street. This section of road used to be part of SH 73 and the speed limit is mostly . At the western end of Brougham Street at the Collins Street/Simeon Street lights, the Christchurch Southern Motorway commences. The speed limit here is . Midway up the motorway is the Curletts Road interchange, a major interchange where two state highways commence: SH 75 to Akaroa via Banks Peninsula and SH 73 to the West Coast via Arthur's Pass.