If you read all the hysteria, we are on the cusp of a massive transport disruption that will entirely transform our current system through gadgets like driverless cars, transport-as-a-service, connected vehicles, taxi bots, various fancy apps and goodness knows what else. Sitting behind all of this will be incredible data processing capability that’s currently almost beyond our imagination – with each driverless car generating thousands of gigabytes of data a day.
This is an exciting future in some respects, if we get it right. But it’s also a future that seems an incredibly long way away whenever I’m unnecessarily waiting at a red light and nothing’s coming the other way – whether I’m walking, on my bike, catching the bus or driving.
Auckland’s traffic lights are controlled by a system called “SCATS”, Sydney Coordinated Adaptive Traffic System. It sounds kind of fancy when you read about it:
The Sydney Coordinated Adaptive Traffic System, abbreviated SCATS, is an intelligent transportation system that manages the dynamic (on-line, real-time) timing of signal phases at traffic signals, meaning that it tries to find the best phasing (i.e. cycle times, phase splits and offsets) for a traffic situation (for individual intersections as well as for the whole network). SCATS is based on the automatic plan selection from a library in response to the data derived from loop detectors or other road traffic sensors.
SCATS uses sensors at each traffic signal to detect vehicle presence in each lane and pedestrians waiting to cross at the local site. The vehicle sensors are generally inductive loops installed within the road pavement. The pedestrian sensors are usually push buttons. Various other types of sensors can be used for vehicle presence detection, provided that a similar and consistent output is achieved. Information collected from the vehicle sensors allows SCATS to calculate and adapt the timing of traffic signals in the network.
In reality though, the system doesn’t work – especially for pedestrians, public transport and at off-peak times. It’s frustrating and I think it hugely undermines the faith people have in Auckland Transport – after all it’s natural to get grumpy when “the system” is unnecessarily keeping you waiting. It’s also very dangerous, as pedestrians frequently and understandably simply run out of patience and just cross the road.
Digging into the detail of why our “dumb” traffic lights are so damn annoying is challenging, but seems to come back to a few key changes that we need to make around shortening signal cycle lengths and shifting to truly “smart” technology.
Shortening Cycle Lengths
An intersection’s “cycle length” is how long it takes all phases of the traffic light to complete. In Auckland most cycle times are 120 seconds or more, whereas industry best practice is 60-90 seconds. Shorter cycle lengths are great for urban areas, walkability and also reduce the frustration and danger of a long and potentially unnecessary wait at a red light:
Though often invisible to the public, traffic signal cycle lengths have a significant impact on the quality of the urban realm and consequently, the opportunities for bicyclists, pedestrians, and transit vehicles to operate safely along a corridor.
Long signal cycles, compounded over multiple intersections, can make crossing a street or walking even a short distance prohibitive and frustrating. This discourages walking altogether, and makes streets into barriers that separate destinations, rather than arteries that stitch them together.
As a pedestrian, and if you know the light sequence for an intersection, there’s often nothing more frustrating than just missing your phase in the sequence. As a driver, cyclist or PT user, while shorter cycle times might mean you’re more likely to not make it through in a single phase and more likely to hit a red light, it also means much shorter waits and a much lower likelihood of unnecessarily waiting.
Moving to shorter cycle lengths is a great example of understanding that human psychology is different to the numbers a computer spits out and – even though it might mean slightly less throughput along a major corridor – the shorter waits and reduction in unnecessary waiting means that the public are almost certainly going to be happier.
Using “Smart” technology
The engineering and maths of traffic lights seem pretty complicated and I’m sure a lot of people spend a lot of time meticulously analysing how to sequence different sets of lights together so that a car can plough through 3 seconds faster. But in this day, when adaptive artificial intelligence and machine learning is becoming a reality, it seems positively archaic to take such a “hands on” approach – especially one that seems to so quickly fall apart if something unusual happens, or doesn’t work for you at all if you’re a pedestrian, or leaves you waiting at a red light with nothing coming if you’re travelling off-peak.
Surely, if we are going to be anywhere near ready for our much hyped transport technology revolution, then we can at least have properly adaptive traffic lights that use smart cameras to know exactly how many vehicles and people and buses and bikes are at the each intersection, know how long they’ve been waiting, know what’s happening at nearby intersections and can run thousands of scenarios in half a second before picking the one that’s most efficient and best gives effect to whatever strategic goal we have asked it to perform. This probably means a complete overhaul of the current SCATS system, but I’d be enormously surprised if there aren’t a whole heap of much smarter software solutions out there which can do this task.
Overall, we should not accept the dumb traffic light system we have in place today. Contrary to many letters to newspaper editors, improving traffic lights will not solve all our transport challenges. However, I’m confident that shifting to shorter cycle times and smarter technology with a relentless focus on finding a better way to optimise across all road users, will make a big difference. Perhaps most importantly for Auckland Transport, a major focus here is a good way of building trust with the public and getting rid of those enormously frustrating and downright dangerous situations of unnecessary delay.