A new-look Manchester St opened in July as the main route for public transport through the city.
Seven bus routes run down the street, including three core lines, which run every 15 minutes at peak hours.
Viastrada transport consultant Axel Wilke said the plans for Manchester St did not "go far enough for achieving bus priority," and suggested adding further driving restrictions to solve the congestion problem.
Wilke proposed banning right-turns from Bealey Ave, or restricting car usage on the Avon River bridge, to direct motorists away from Manchester St.
Mann said Manchester St was not a "fast way to get across town" and suggested motorists use adjacent one-way streets instead.
Christchurch Transport Operations Centre Senior Traffic Advisor Steven Mann said motorists continuing to use Manchester St as a "mass-transit through-way" despite its new design as a "bus-priority route".