There’s an interesting article in today’s NZ Herald that looks at the traffic effects of when there was a power cut last Monday, with a specific focus on why having the lights turned off might have actually made traffic better. Here’s the article:

Flow-on effect of no lights

By Heather McCracken
4:00 AM Sunday Jan 31, 2010

The same intersection at 4.50pm last Monday, during the power cut (L) and at 4.50pm on Tuesday, when the traffic lights were working (R). Photos / Supplied by Studio TDES

It should have been a commuter’s worst nightmare: a rush-hour power cut blacking out traffic lights across Auckland.

But reports of a free-flowing commute during Monday’s massive evening outage have prompted questions over whether so many signals are needed at all.

Sarah Lilburn filmed traffic flow outside her apartment on Union St in central Auckland at 4.50pm.

Her footage shows traffic flowing freely through the busy intersection with Wellington St and on to the Northern Motorway.

A comparison video taken at the same time the next day showed vehicles edging through the junction and long queues of traffic waiting to enter the motorway.

Lilburn thought the unusual circumstances on Monday made drivers more courteous and patient.

“Normally there is a lot of beeping during rush hour but there was none during that time,” she said.

“You could see some people hesitating longer than they needed to, but the people behind them didn’t beep because they seemed to understand.”

Radio Live host James Coleman said there were no delays during his drive to work during the evening peak hour.

“Traffic flowed beautifully, it was absolutely amazing.”

He said drivers appeared to be more careful and alert when navigating uncontrolled intersections, and thought traffic lights sent them into “autopilot” mode.

“I think people approach intersections with a little bit more care knowing there’s an unpredictability about people’s behaviour.”

Coleman called for a traffic light-free day to be trialled in Auckland but acknowledged issues around pedestrian and cycle safety.

There were no crashes or major incidents reported during the outage, which cut power to 50,000 homes from just before 5pm.

Auckland city road policing inspector Gavin Macdonald said delays at some major intersections were eased by officers directing traffic.

“I think drivers realised if they didn’t behave themselves, they would probably get gridlocked or prosecuted,” he said.

Most traffic lights are installed, monitored and maintained by local authorities.

Last year cyclist Matt Hancock complained about encountering 14 sets of lights during his 5.5km commute from Ellerslie to Newmarket – averaging one every 390m.

The Herald on Sunday counted the lights on other major routes, and found commuters from Panmure and New Lynn struck traffic lights every 550m on average.

Auckland City Council network performance manager Karen Hay said drivers generally behaved more cautiously during a blackout, but would eventually take more risks if those circumstances became regular.

Traffic signals were a last-resort for vehicle control and were only used after a review of traffic demand, crash rates, and pedestrian and cycle safety, she said.

Alternatives included roundabouts, which allowed more free-flowing traffic, but sometimes led to long delays on side roads.

Hay said traffic light phasing – how quickly the sequence is completed and how sets interact with each other – were set by a software programme and adjusted by road sensors according to demand.

An advantage of signals over roundabouts was that lights could be overridden from two control rooms, a regional traffic management unit and an Auckland City Council unit.

AA motoring affairs general manager Mike Noon said there had been cases where removing lights had improved traffic flow and safety.

“But what happens is you have situations were you just can’t get into the traffic, and you get big delays,” he said.

“Are we going to get away from having traffic lights? No. We need them.”

In terms of the particular Wellington Street case, the reduced congestion was probably due to the ramp metering lights being off, but it’s an interesting question to ask overall – whether traffic lights make things better or worse. Often in a situation when everyone’s traveling slowly and carefully, it seems like the road-space is used more efficiently when you don’t have lights – as people let others in, there’s a sort of “your-turn, my-turn” arrangement that appears, and so forth. I do agree that it’s the unusualness of situations when the lights go out that makes you more cautious and courteous, and perhaps that would wear off over time. However, I do think that unless the signalling of traffic lights is very well managed, there is certainly the chance they do more harm than good from a traffic-throughput perspectives (ever sat at a red light forever when nobody’s coming…. exactly!)

Perhaps what’s more interesting is looking at it from a safety perspective. I am completely unsurprised that having traffic lights go out didn’t lead to chaos on the roads from a safety perspective. The most important factor determining how safe an intersection is, is how cautious everyone is being. In that respect, while traffic lights improve safety from a “it’s definitely your turn or it’s definitely not your turn” perspective, I think they achieve the opposite in terms of caution – as when you’re driving your only focus is on getting through before the light goes orange and you effectively have your “blinkers on” to everything else. A contrast is at a roundabout where you do have to think, you do have to be careful and you do have to go slowly. Unsurprisingly the accidents that happen at roundabouts are usually minor, while those that happen at traffic-light intersections are often major.

Road safety is in many respects counter-intuitive, as the general thinking is that the easier the road is made for the driver, the safer it will be. While this might be the case out in the country, in the city I reckon the opposite is probably true. The safest roads are likely to be those that are a bit too narrow for comfort, have a funny 5-way intersection without it being clear who always has the right of way, that has on-street parking on both sides that makes the road seem narrower than it is, and so forth. This is because all these things slow people down. Getting rid of more traffic lights would probably achieve the same safety benefits, as drivers would have to think more and be more careful.

In wider terms, perhaps the huge focus of road-rules on defining clearly who has the right of way and who doesn’t – simply hasn’t worked and is in fact counter-productive as it stops us from being wary of the unexpected. After all, how many people have died on the world’s roads over the past 100 odd years of motoring – millions? How can we say that the current system has worked?

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  1. As mentioned when there is nothing to tell you what you have to do you actual have to start thinking for yourself so safety comes from that. Its better to have 100 small crashes where no one is injured than 1 major accident that kills someone. One of the reasons this particular intersection was free might be due to Hobson St. A colleague reported it took over 40 minutes just to get from the bottom of town to the motorway to head west and then another 40 minutes to get to Te Atatu

  2. I do think it’s hard to put the difference down to just the lights being out. Volume is definitely a lot lower during the cut to my eye. A lot of people I know of knocked off early that day for example.

  3. I think it is obvious that the NZ and US way of managing traffic and intersections is much more focused on traffic lights – I find in Europe there is much less use of them, and much more use of shared spaces. I would say the main aspecrs of shared spaces are pretty much used as per default on the majority of streets in Switzerland.

  4. People will play it safe for one or two days, once it starts becoming normal thats when people will start taking more risks. However we do have to many traffic light on our roads, however we need to keep them in the city as a deterrence to drive.

  5. There are about 12 sets of traffic lights in Queen Street. No wonder it takes longer by bus than walking. At least the non-crossroads lights should go (i.e. all intersections with one road joining) and all ped crossings too.

  6. “There are about 12 sets of traffic lights in Queen Street. No wonder it takes longer by bus than walking. At least the non-crossroads lights should go (i.e. all intersections with one road joining) and all ped crossings too.”

    Yeah, screw the peds, what are they walking there anyway? Can’t they see it’s A ROAD!!!

    Seriously, I’m not a big fan of traffic lights at all. But until we get away from the four-five-six-lanes-without-any-interruptions-or-pedestrian-islands “motorways” that go through out downtowns (Nelson Street, Hobson Street, parts of Queen Street), how are peds going to be catered for?

  7. How many lights would that get rid of anyway? Shortland St and Wyndham St only I think…. and those lights are useful for pedestrians.
    If we want to make Queen St faster for buses, then bus lanes seem like the obvious solution.

  8. By turning Queen St into pedestrian mall with two lanes in the centre for buses, you would cut out half the intersections, i.e. anything but the main cross routes of Wellesley, Victoria and Customs St.

    These remaining three intersections would then only need two phases at the lights as you would have no need for any turning traffic, i.e:
    Phase 1: Buses and pedestrains moving north south.
    Phase 2: General traffic and pedestrians moving east west.

    Depending upon bus traffic levels you might also be able to remove the mid block pedestrain crossings, as pedestrians might be able to easily cross the two lane bus road informally.

    That would not only speed up the buses, but also the rest of the traffic in the CBD.

  9. We complain about the traffic and blame other drivers, but could it be traffic controls that are the problem? You bet it could. Traffic lights are an almost entirely unnecessary evil. They flout basic safety principles by taking our eyes off the road. They encourage inappropriate speeds. They support a vast control and enforcement industry. And they are based on a fatal flaw: priority. Why do we “need” lights? To interrupt the priority streams of traffic so others can cross. Remove priority (as during this signal failure) and you remove the “need” for lights and the need for speed, enabling everyone to do what is natural, fair and intrinsically safe: approach carefully, and filter more or less in turn. A lights-off trial we’ve been running in Portishead has proved the point. Since the lights were switched off on 14 September last year, journey times have fallen by over 50%, with no accidents, incidents or near misses. Pedestrians, including schoolchildren and pensioners, report a greater readiness among drivers to give way. Sociable self-regulation is proving infinitely more efficient, sustainable and convivial than the miserable system of control imposed by misguided traffic engineers and policymakers. A final point: de-regulation needs to be accompanied by a culture change and streetscape re-design to express a social context. More on this at FiT Roads and Free to Choose Free to Move.

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