The NZ Transport Agency says ramp signals are just one tool to optimise traffic flow and ensure the safe and smooth running of the entire Auckland motorway network.
Ramp signals similar to those already operating where State Highway 20 joins State Highway 1 will help to regulate traffic flow on both ramps leading in the Waterview Tunnel and the east-bound ramp out of the tunnel.
“Like all the other ramp signals on the motorway network, they will only operate when there’s a need to optimise traffic flow, that could in reality mean they are used very infrequently,” says Brett Gliddon the Transport Agency’s Auckland Highway Manager.
“We don’t expect this to lead to significant queues and headlines suggesting the ramp signals will create gridlock are misleading.”
The signals are also an important part of the extensive safety systems installed at Waterview and will help prevent traffic entering the tunnel if there’s an incident.
When the Waterview Tunnel opens in April this year, as part of the Western Ring Route it will provide a second route through Auckland, bypassing the city centre, creating greater reliability and resilience.
It will also provide more transport options including bus lanes and walking and cycling connections.
The Western Ring Route will provide a better balance of traffic flows across the entire road network, it is not designed to remove congestion altogether.
Recently the Auckland Transport Alignment Project identified the scale and pace of Auckland’s growth, which is ahead of any projections, and determined that three major responses are needed to keep Auckland moving over the next thirty years.
The Western Ring Route is one part of the infrastructure package, but technology and managing travel demand and behaviour will also play equally important roles.
This increasing demand has been anticipated and built into the operation and management of the Waterview Connection which includes the use of ramp signals.
Assertions by some commentators that the ventilation system within the Waterview Tunnel can’t operate properly if cars are stopped inside are incorrect.
The safety systems, which include ventilation, within the Waterview Tunnel are designed to operate in any conditions, including free flowing and congested traffic.
Best practice across the world for managing tunnels is to have the ability to limit the amount of time traffic spends queuing inside tunnels.
This is because, while a range of safety measures and equipment will ensure it operates safely if there is an incident, they can escalate more quickly in the tunnel, for example if a car overheats it can turn into a fire.
The ramp signals are not operated in isolation and are designed to be controlled by operators who are managing the entire road network. Ramp signals are one of many tools to manage the network, these include things like variable speed signs, variable message signs to inform customers and direct traffic, and the over height detection system. Travel information and social media are other important tools to encourage certain driving behaviour and patterns such as spreading travel times and the use of alternative routes.