An 800m stretch of Berrigan Drive between the Kwinana Freeway and the Jandakot Road roundabout is set to be duplicated.
The design for the duplication means it would need to acquire land from three lots on Jandakot Road before a builder is locked in.
The road construction tender was expected to be awarded this month but will now be advertised in late March due to service relocation requirements.
The City has also taken a step towards constructing a second carriageway between Stock Road and Spearwood Avenue on Beeliar Drive in Beeliar.
It will spend $2.1 million hiring Tracc Civil to take care of stage one, which involves upgrades to the 1.5km stretch of road between Durnin Avenue and Spearwood Avenue.
The existing road will be duplicated so two lanes run in both directions.
The lanes will be divided by a median island and feature an on-road cycling lane on both sides.
Stage one also involves the reconstruction of the Beeliar Drive and Birchley Road intersection.
Construction should start within six months.