The NZ Transport Agency says it will raise variable speed limits near the Waterview Tunnel to a maximum of 100km/h.
Variable speed limits mean the speed limit changes depending on the traffic flow, and are used to manage traffic congestion.
The limits will be extended on sections of State Highways 16 and 20.
"We want to ensure that people's journeys on the motorway are as safe and easy as we can make them. Variable speeds are increasingly being used to match speed limits with the conditions and provide the right balance between safety and keeping traffic flowing smoothly," says Brett Gliddon, the Transport Agency's system design manager.
"The motorway system around the tunnel and through the central motorway junction is complex with higher traffic volumes and a significant amount of lane changing and the speed limits need to reflect these conditions while also ensuring we keep motorists safe."
Speed limits inside the tunnel will remain at 80km/h due to the higher risks of an enclosed tunnel environment.
More physical infrastructure will need to be installed on the motorway system, as well as a legal process completed before the variable speed limits can be put in place.