Across the road network there are some locations which we have received a high number of feedback and comments on why ramp signals are active when the motorway appears to be free flowing or that traffic movement on to the motorway is slow.
Ramp signals at Oteha Valley Road, Greville Road and Constellation Drive are grouped together to manage the motorway network in the city bound direction. There are two locations were flow breakdown normally occurs, Greville Road and Constellation Drive. Although Oteha Valley has no issue with merging, the on-ramp flow contributes to the merging and congestion issues further along the motorway. By having signals at the on-ramp at Oteha Valley we can promote more equity for traffic entering at later on-ramps. This is done by sharing (proportioning) the demand for traffic wanting to use the motorway across these three onramps. This then improves efficiency of the motorway and provides more consistency in travel times.
Grouped (co-ordinated) on-ramps share storage and delay. The increase in ramp signal red times is due to higher demands in this section of the motorway network from the surrounding suburbs and traffic coming from further north. Drivers are advised that we observe congestion between 6:00am and 10am and at weekends.
We generally do not operate these ramp signals in the weekends due to the very high numbers of vehicles using the on-ramp bypass lane from Greville Rd. Switching the ramp signal on at Greville Rd would unfortunately not help the motorway flow under these conditions. During weekdays when the numbers of T2 vehicles is low then the ramp signals have a better chance to manage the network.
Learn about the SH1 Northern Corridor project(external link)
Ramp signals at Tristram Ave, Northcote Rd and Esmonde Rd are grouped together to together to manage the motorway network bottleneck near Esmonde Rd.
Drivers are advised that we regularly observe congestion between 6:15am and 10:15am in the morning heading to the city. In the afternoon when the Harbour Bridge lane configuration is changed we observe congestion starting from 4pm.
At the end of the peak, Tristram Ave and Northcote Rd ramp queues may be cleared. However when there is still the last remnants of the peak congestion around Esmonde Rd the system will remain active meaning all three ramps will remain operating until the congestion finally clears and the remaining ramp queue is cleared on Esmonde Rd.
We have also activated the signal at Akoranga Drive - northbound in the mornings. This is to discourage traffic from using Northcote off-ramp and making U-turn movement toward Northcote on-ramp southbound. The U-turn movement is a queue jumping technique which adds to the congestion at the Northcote Road interchange, increasing congestion and wait times for those patiently waiting their turn from Northcote Rd.
Learn about the SH1 Northern Corridor project(external link)
Lake Road leading to the Esmonde Rd on-ramp, like some long roads used to access the motorway has its signal timings determined by the ramp metering system which optimises the motorway network. The ramp signal at Esmonde Road on-ramp has been given a higher system priority than other signals upstream from this location due to its location closer to a bottleneck on the network and the lack of alternative routes available to motorists, especially those from the Devonport area. The signal timings operate in such a manner as to replicate the historical on-ramp volumes that accessed the motorway over a peak period prior to the introduction of ramp signals.
The Wellington Street on-ramp metering is in place to ensure the safety of vehicles entering a multi merging motorway environment close to an enclosed structure (Victoria Park Tunnel). The lanes from both the motorway and the ramp are quite steep at this location. Psychologists have told us that the surrounding concrete walls, darkened (but illuminated) entry to the tunnel, can also create a visual distraction for the driver and cause drivers to break unexpectedly.
These signals also manage congestion on the motorway as far north as the Auckland harbour Bridge. This ramp signal is also part of grouped (co-ordinated) set of on-ramps that share storage, and delay vehicle entry onto the motorway with ramps that connect from the Port and North-Western Motorway connecting ramp. Long red times are evident during the PM peak period. This is because priority is given to traffic coming from the eastern side of the city and port area that use the link ramps. This is done to discourage travel through the CBD at this time of day. Motorists on the western side of the city have the alternative option of using the Fanshawe St on-ramp which does not operate in the PM peak due to the addition of the peak lane in Saint Marys Bay.
They ramp signals operate during the day to aid in the safe entry of vehicles into the Victoria Park tunnel.
