The $500,000 intersection
Traffic lights don't come cheap. WILL HARVIE stops in Redcliffs to count the cost.
Augusta St in Redcliffs was first mentioned in records in 1907. And in all the time since, traffic lights haven't been necessary for drivers wanting to turn onto Main Rd. But this year, Christchurch City Council and Foodstuffs together spent almost $500,000 installing traffic lights, "pedestrian presence detectors", traffic cameras, road paint, kerb enhancements and other works in downtown Redcliffs.
The new "signalised" intersection is something of a case study on the cost and complexity of infrastructure repairs post-quake and the political might of a large corporation. It's too late to ask whether this intersection needed traffic lights, but there are some yarns in that question too.
Foodstuffs, which operates the recently re-opened New World grocery store in Redcliffs, declined to discuss the intersection's cost and council was reluctant to break down actual costs for commercial reasons. But council fronted managers from the Christchurch Transport Operations Centre (Ctoc), who provided estimates on the three-way intersection.
So the eight red-yellow-green traffic lights, plus the pedestrian cross-don't cross lights, cost something like $25,000 to $28,000 total. Traffic lights with advance green signals — there are three of these in Redcliffs — don't cost a lot more than those with standard three lights.
The seven steel poles holding these items up cost less than $1000 each, but the one pole that's substantially thicker and taller — it holds up a mast arm thrust out over the road and two traffic cameras — cost about $10,000, including the mast arm and installation. A bigger pole requires a larger and stronger foundation, which costs.
Each pole is topped by a device ($600-$700 each) that controls the lights and communicates with the roadside traffic controller ($30,000) and back to Ctoc. The controller is the computer brain that takes data from various points around the intersection and algorithms them into, for example, permission for a pedestrian to cross the street.
The two cameras at the intersection cost several thousand each to buy, mount and wire. One is a police camera that, it is hoped, reduces crime by its presence and provides evidence of crime. The second is a NZ Transportation Agency camera taking still photos roughly once a minute. Photos from this type of camera are posted to Ctoc's website, tfc.govt.nz, although the Redcliffs shots are not available at the moment.
These help with "incident management and optimising traffic management", says Ctoc manager Ryan Cooney.
Data collectors include the pedestrian buttons — they work, despite what you hear, says Cooney — the yellow pressure pads on footpaths, and six "pedestrian presence detectors". These look like the eyeballs of Disney's animated character WALL-E and they detect when pedestrians are no longer in place to cross (perhaps because they've jaywalked). If this happens, the pedestrian crossing phase is dropped and vehicles directed to move.
Another dataset comes from detector loops cut about 50mm into the road and sealed with tar. They leave a distinctive box-shaped scars where the first car at a red light should rest. The loops detect heavy metal objects and signal this to the computer brain. In theory, one waiting car should trigger the computer to give it a green light. Some bicycles will trigger the loop, but carbon fibre and aluminium bikes not so much.
The loops, installed cost $1200 each, are fairly low-tech but do the job. New tech is available, including radar devices, but these can cost $10,000. Council has bought a radar device for use with the tram.
All of this stuff has to be tough enough to withstand salty air, high winds, out of control vehicles and vandals. Pedestrian crossing buttons are especially prone to abuse. And then everything has to be wired together though underground ducting and supplied with electricity.
All that has to avoid existing water pipes (fresh, rain and sewage) as well as internet and electrical cabling. Somebody had to prepare the plans, the suppliers and contractors all make a profit, the workers earn wages and there's GST.
All up, the Redcliffs intersection cost about $300,000.
And that doesn't include about $200,000 in roadworks that was needed to repair earthquake damage and add the Coastal Pathway to the road layout. These costs included new kerbs, new pavement and the like.
So $500,000 to get Augusta St and Main Rd up to spec. Actually it will probably come in slightly under budget, says Ross Herrett who works for council and Scirt.
So now for those yarns. There are two versions of how this intersection came to be signalised, council's and Foodstuffs-New World's. Council's is laid out in a remarkable December 2012 meeting minute, which alleges that New World told the Hagley-Ferrymead Community Board that it wouldn't rebuild the supermarket "until traffic signals are installed". The community board really wanted the supermarket back and asked council to "urgently" fund the intersection.
A 2012 background report prepared for council asserted that "99.5% of the year the intersection would not warrant signalisation". The only time traffic lights were needed was "mid-afternoon on a summer Sunday". The report goes onto state there was no budget for the intersection and that Foodstuffs should be asked to contribute.
It is broadly the case that developers fund new traffic lights that primarily benefit the development. "Private developers have funded the new intersections in sub-divisions etc," said a council spokeswoman via email.
Foodstuffs "did not threaten to not rebuild the supermarket", says Roger Davidson, general manager property and retail development at Foodstuffs South Island, via email. "We asked the Christchurch City Council to evaluate signalising the intersection (as we had done prior to the earthquakes) so that it maximised the use of the supermarket site for the whole community," he said.
In any event the matter went underground until July 1, 2013, when council released it's 2013-16 three-year plan . Item 7693 on page 305 budgets $150,000 of ratepayers money for the Augusta-Main intersection.
A deal had been struck. Foodstuffs and council would each pay half the cost of the $300,000 signalisation and the $200,000 worth of roadworks would come from Scirt and other sources.
"We believe that the controlled intersection makes travelling and walking in the area safer and has benefits for the whole community including our customers," says Davidson.
And two years later, lights started changing at Augusta and Main.
When to let another driver into traffic
The Christchurch Transport Operations Centre hates "green waste" — when a light is green but cars are not moving. One creator of green waste looks polite but actually worsens traffic, they say. That's when drivers facing a green light wave another driver on a sidestreet into the road ahead. Don't do that, says Ctoc. If your light is green, the driver on the side street can wait as you and others behind you advance. Let other drivers into traffic once the green light turns, Ctoc asks.
Read more by Will Harvie on the rebuild: