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?