Newsletter #54 - 20 November 2017
This past week, the focus has been on briefing the four locally-based Members of Parliament about planning for the potential growth and transport demands in the Warkworth area. On the Hill Street front, there is again nothing new to report.
NOTE: This week's issue has many graphics that can be enlarged by clicking on them. Then, they can also be downloaded by right clicking and then saving on your device.
STRUCTURE
In the absence of action, we’ve been driving around Auckland and looking at how other growth areas are coping. The story is disturbing. The Auckland planning department are allowing intensive suburbs at a faster rate than Auckland Transport can reconfigure intersections to cope with changing traffic patterns.
For example, Riverhead (http://bit.ly/2iy7OcB) is a maze of unconnected new subdivisions on a grid of old unformed paper roads. See for yourself:
Even if there is a structure plan or a network of paper roads, Auckland Council allows developers to do what they want. This is endemic with the number of non-notified resource consents issued for non-complying activities. You wonder, what’s the point of communities framing ‘sustainable’ plans when council planners unilaterally ignore them? It seems that the council is determined to lower our expectations of them.
Warkworth has a similar history and there are no signs of Auckland Council acting any differently. Even the most recent subdivisions have paper roads that do not logically connect with neighbouring properties. Look at all the unformed or closed paper roads in this map:
The lack of an interconnected road network puts strain on the few roads that do connect. Hence, the amount of traffic that needs to use the Hill Street intersection.
But even the proposed order of the construction of the ‘ringroad’ around Warkworth lacks logic. In fact, it is in the reverse order of need. The largest growth in traffic has been on Sandspit Road. The Sandspit Link is ‘last off the rank’, after the Matakana Link. The Western Collector may be built first when Hudson Road already provides a link to the west. According to the business case for the Matakana Link, it would be optimal is the Matakana Link and Sandspit Link were completed at the same time.
Whereas the Warkworth area relies heavily on the Hill Street intersection as a hub, Riverhead has a network of arterials to connect with the State Highway network. There are a combination of roundabouts and t-shaped intersections. Locals rely on Google Traffic to find the intersection with the least congestion. It is interesting to see what works and what doesn’t.
CONFLICTED
The short-term upgrades to the Hill Street intersection puts us in a conflicting position. Based on the NZTA’s public statements and previous designs, we know they prefer traffic lights to roundabouts. Auckland Transport has conjured up a combination of traffic lights and barriers. Auckland Council has built a roundabout in Kowhai Park. Should we support a traffic light-based short-term solution if it risks being the long-term solution?
NZTA has given Auckland Transport $2million for the investigation and design of a major upgrade. Traffic sensor equipment (those beige boxes at the side of the road) have appeared on all branches of the intersection some distance from the intersection. Could this equipment be simply counting traffic or form part of a linked traffic light system?
We haven’t received any straight answers but would appreciate if the equipment was part of the traffic monitoring. We hope that Auckland Transport has good data.
Anyway, transport engineer Roger Williams has been keeping in regular contact with Auckland Transport. As an alternative to the barrier, he has offered several alternatives. Here is the latest, seen in the Mahurangi Matters (http://bit.ly/2jBZKLa):
SEQUENCING
At approximately the same time as the Northern Gateway Tollway started construction under the last Labour Government in 2008, a project commenced for a major upgrade of Hill Street, culminating in this design in 2010:
Effectively, all the branches to the intersection were linked by traffic lights and there would be no queuing between Elizabeth Street and State Highway 1.
With the latest proposed short-term fixes, Roger’s alternative design is a somewhat scaled-down version of the 2008 major upgrade. Here is a possible diagram of the phasing:
Phase 1p is activated by the pedestrian crossing between Kowhai Park and the traffic island. There would also be no queuing between Elizabeth Street and the State Highway. Without widening Sandspit Road between Elizabeth Street and Matakana Road, the left-turning lane into Elizabeth Street and the left-turning lane onto the State Highway would need to combine.
The trade-off of bringing Elizabeth Street into the light phasing could be an additional 20 seconds to the cycle. In other words, all the other traffic could wait a further 20 seconds. On the other hand, the certainty of a clear path for Sandspit Road traffic would provide a steadier flow of more vehicles through each green light phase.
We’ve counted the length of green light phases and how many vehicles can clear the intersection during a phase. The 8 to 10 second green light phase of Hill Street can clear 5-8 vehicles, the 20-second right turn into Sandspit Road can clear 15-18 vehicles, and the occasional 30 to 40 second green light phase can clear 30-42 vehicles.
The least efficient is out of Sandspit Road where as few as 10 left-turning vehicles can clear a 20-second green light phase. We reckon that a 20-second green light phase for Elizabeth Street can clear queues back to Falls Street. We also reckon that a 10-second green light phase for Sandspit Road at Elizabeth Street can clear queues back to the Matakana Road intersection.
Why 10 seconds? Well, linking Elizabeth Street with the lights only deals with the first hurdle of the Hill Street intersection. The second great hurdle is the confluence of Matakana Road with Sandspit Road.
Currently, the courtesy of queuing Matakana Road traffic allows Sandspit Road traffic through at peak times. Any improvement to the flow of traffic between Elizabeth Street and the State Highway could result in more difficulty for Sandspit Road traffic to merge with Matakana Road traffic.
You will notice that we’ve put a question mark on our diagram. If there was a traffic light simply stopping Matakana Road traffic to let Sandspit Road traffic through, what about traffic turning right into Sandspit Road? How would they know that Matakana Road traffic is facing a green or red light? In other words, any controls on that intersection would require being linked into the whole intersection’s sequencing – like the 2008 major upgrade.
Essential to any effective signal sequencing are sensors. If all branches of the intersection are to be linked by traffic lights, sensors need to be at the intersection as well as a distance from the intersection where queuing is tolerable. On our diagram, the queue sensors are at a distance from the intersection where a queue that length will clear a 20-second green light phase.
We aren’t happy with Auckland Transport’s refusal to look at the width of Sandspit Road between Matakana Road and Elizabeth Street. Only one lane on Sandspit Road at Elizabeth Street serving two different green light signals is just nuts. The increased amount of Sandspit Road traffic turning right at the traffic lights onto the State Highway will only get worse with the opening of the motorway and new shopping centre near that junction. Auckland Transport won’t even consider our suggestion of reconfiguring the lanes out of Sandspit Road at Matakana Road, which are shown below:
The proposed short-term changes is that they were in response to the Elizabeth Street trial, which several Sandspit Road users supported. The irony is that they will result in increased frustration for Sandspit Road users to access Elizabeth Street.
NEVER GIVE UP
We were forwarded this reminder from 2000 that Hill Street has been a bone of contention for some time. It is also a reminder that now is more important than ever to fix New Zealand’s worst intersection.
THANK YOU
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