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On the surface, traffic lights seem pretty basic: Red means stop, amber means slow down and green means go, but there's a little more to it behind the scenes.
The first set of automatic traffic lights in Australia was installed in October 1933 at the Kent and Market Street intersection in Sydney, New South Wales, after a trial of lights manually operated by police from 1928.
Activated by an electromagnetic sensor in the road, these automatic traffic lights removed the need for police to operate the lights.
"A number of men, evidently pleased to see that the traffic policeman was missing from his accustomed spot, drove gaily across the intersection in defiance of the red lights."
Fast-forward nearly a century, and there are tens of thousands of traffic lights across Australia, and nearly all of them are controlled by a complicated system the average person will never see nor consider.
We spoke with Chris Miller, a self-proclaimed "traffic nerd" from the Department of Transport Victoria, about how traffic lights actually work.
How do traffic lights work?
Chris Miller, Department of Transport Victoria: It seems pretty simple: you show up at the traffic lights, and they turn green, and away you go. But, it's quite a complex thing to design.
We all remember doing algebra in school and wondering what the hell you'd ever use it for. I can tell you signal engineers do. I've seen some of their calculations and algorithms, and it's enough to break your brain.
We manage over 4000 intersections in Victoria as the Department of Transport. Depending on their location and the time of day, they operate differently.
For example, if you're driving around at three in the morning and you get to an intersection, the light's red. You'll probably find that when you pull up, the light will fairly quickly go green as long as nothing is coming in the other direction. At those times, the light is triggered by a magnetic loop built into the road pavement.
As you approach the intersection, the magnets under the road detect that a large chunk of metal has just arrived. Then, that'll send the signal to the controller box beside the traffic signal to tell the controller that there's a demand here. If everything's safe, it will switch to green so that we can get this person on their way.
However, let's flip to the same intersection, but at 7:30 in the morning, you'll find that it will operate quite differently. We prioritise our signals to give a nice, easy flow to where most people are headed. We've got data from each intersection that counts the cars, knows what speed they're doing, and knows what time of day has the biggest demand.
In the morning, the majority of people are heading towards the city. The traffic signals will give priority to city-bound traffic and extend the green time for that direction of travel. Conversely, if you're coming in the opposite direction, your red light will last a longer time.
The traffic signals will give priority to city-bound traffic and extend the green time for that direction of travel.
It's all about numbers, and we want to keep as many cars moving as possible. So if you've got 2000 cars heading in one direction and 400 headed in the other, all those 400 are going to have to wait that little bit longer.
Intersections also don't work independently. They tend to be linked to other intersections along specified routes. Again, we look at the data, the travel patterns, and the demand.
We also try to prioritise public transport where we can because, at the end of the day, moving one tram with 150 people on it is more important than moving one car with one person in it.
Do traffic lights change for emergencies?
Chris Miller: We've got what we call the real-time signals operations team, and they sit in the Transport Operations Centre during peak periods. So, if we've got a collision or we've got some major road work, they'll prioritise the traffic lights so that we'll keep the area clear.
However, all of the surrounding roads and the detour routes people would need to use around them are optimised to minimise delays as much as is humanly possible.
Also, during the AFL season, we've got dedicated people watching the MCG ingress and egress, making sure that thousands of pedestrians can cross the road and enter Richmond Station to board their train.
At Christmas time, we even have them based at shopping centres, so they'll be in Chadstone Shopping Centre, making sure that people can get in and out of the car park safely at the busiest time of year. There's probably a lot more to it than people realise.
How often are traffic light timings updated?
Chris Miller: We have something called the network optimisation program that came out of a Smarter Roads project. Essentially, what that's done is that it allows dedicated signal engineers to revise every single intersection in Victoria. What they're doing is they're looking at the way the intersection operates.
A lot of the time, an intersection might have been there for years, and then a new housing estate will pop up nearby. So, the demands on that intersection may have changed since it was first put in. Those signal engineers will look at it and do their absolute best to reduce travel times.
But they might also look at it and say: 'Look, that right-hand turn lane is no longer long enough, and we've got people queuing in that right coming out of that right turn lane, which might be blocking through traffic'. They'll extend the right turn lane to make it longer so that the queuing traffic can get out of the way, and the through traffic can kind of get through.
Before the Smarter Roads program, an intersection was probably reviewed once every four or five years. Whereas, as I say, every single intersection across the state of Victoria is being analysed and optimised to get the most out of it over two years.
A lot of people may not notice it because it might only be a 10- or 15-second improvement in travel time. If you're achieving a 15-second reduction at seven intersections along your route, well, then you've actually got to where you need to go three or four minutes earlier.
If people see faults or think they have suggestions, we're always really keen to hear them. The community is our eyes and ears. The Transport Operations Centre is open 24/7. People just need to ring 13 11 71 in Victoria, give us a suggestion, and we'll put it on the list and have a look at it.
Zane Dobie comes from a background of motorcycle journalism, working for notable titles such as Australian Motorcycle News Magazine, Just Bikes and BikeReview. Despite his fresh age, Zane brings a lifetime of racing and hands-on experience. His passion now resides on four wheels as an avid car collector, restorer, drift car pilot and weekend go-kart racer.
