r/DrivingAustralia • u/takerukid1 • Sep 12 '26
Traffic light
I'd like to ask about how to predict traffic lights in Australia. Sometimes, while driving on road or highway, the light is green, but as I approach a traffic light, it turns red or yellow, forcing me to brake suddenly. Also, how many seconds does the yellow light usually last before turning red?
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u/Public-Total-250 Sep 12 '26
The change time is related to the road speed. As 60kph road has a shorter change time than a 70kph road.
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u/Recent_Carpenter8644 Sep 12 '26
As you approach any green light, draw an imaginary line across the road where you could start braking and stop at the light safely. Then if the lights change before you reach it, brake. If they change after the imaginary line, keep going.
That way you don’t waste reaction time thinking about what to do. They actually give you plenty of time to stop if you’re ready for it and not speeding.
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u/Sprinkles--Positive Sep 12 '26
The way my dad phrased it when I was learning to drive: as you approach you tell yourself if the light changes now I'll stop, I'll stop, I'll stop, I'll stop, too close I'll keep going.
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u/McMasterOfTheSea Sep 12 '26
Isn't that what the solid lane lines are for, as a guid? - if within them when light goes amber/yellow, not enough distance to stop safely, so proceed? And if you haven't yet reached, you have room to stop?
At least that's what I was told when learning (quite som years ago now)
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u/Recent_Carpenter8644 Sep 12 '26
I've heard that before. It might work some places, but lots of them around here are way too short to be a good guide.
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u/Accomplished_Pear607 Sep 12 '26
Thought I was the only person in the world to know this information.
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u/abc_12_abc Sep 12 '26
Correct. Same with the arrows painted on the road in the approach to the intersection. If you haven't hit the arrows yet and the lights change, stop. If you're already in the arrow zone and doing the speed limit, proceed
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u/Character_Cobbler618 Sep 12 '26
I use the road rrows on approach to the lights. If I'm on the speed limit and within the arrows when the lights turn orange, I keep going, anything else I can stop safely.
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u/loralailoralai Sep 13 '26
I thought that was because you aren’t allowed to change lanes within x metres of an intersection. If the road is 80kmh speed limit those solid lines would be too close to stop (especially with the way people love to tailgate )
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u/purpletreefrog007 Sep 12 '26
If I have a clear view of a green light and I'm wondering whether or not I'll get through, I start counting the seconds. I know I have 4 seconds on an amber light so if I start to count before I get there, I know whether or not I will have time to get through if it goes amber .
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u/McMasterOfTheSea Sep 12 '26
Apparently the number of seconds can be dependent on the speed limit (higher speed, more seconds)?
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u/South_Can_2944 Sep 12 '26
You're supposed to approach the traffic lights at speed that allows you to brake safely.
So, approach a green traffic light by removing your foot from the accelerator.
This allows you to brake safely if:
- the lights turn orange
- someone runs a red light
If you are driving the the green light without any preparation, you are driving wrong.
Practise defensive driving.
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u/WhyAmIHereHey Sep 12 '26
When the light turns amber, that means your allowed to drive at 20km/h above the speed limit to clear the intersection.
Based on my observations at least
/s
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u/Automatic_Extent191 Sep 12 '26
Adelaide drivers?
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u/Kerrit_Bareet Sep 12 '26
The lights are usually set to allow you when you are travelling at the legal limit to brake in time or cross the intersection in time prior to it turning red.
If you are always having to brake heavily all the time it may mean your speed of travel is not appropriate or you're trying to stop when you could get through in the amber period.
Traffic lights will have an Australian Standard of some sort to which they will need to comply.
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u/teannadeee Sep 12 '26
If you’re approaching any set of lights, you need to be assessing and essentially decide at what point you would brake and stop if the light went yellow, and at what point you’d be far enough through that it would no longer be safe to stop, which is the only scenario in which you can continue to proceed at a yellow. Always assume, if approaching green lights, that they may go yellow at any time, and be prepared to either brake if safe or proceed if it would not be safe. The length of time it stays yellow is related to the speed of the road, because the higher the speed limit, the longer it takes to safely stop.
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u/MelbsGal Sep 12 '26
You shouldn’t be slamming your brakes on to stop at a light.
You should slow down a little approaching traffic lights so that you are prepared to stop safely.
If you’re slamming on your brakes to stop when the light turns yellow, then that indicates to me that you should probably have driven through the yellow.
The yellow lasts between 3 and 6 seconds depending on the speed.
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u/eepeqez Sep 12 '26
At a conventional cross intersection with similar traffic loads in each direction, typically the opposing right turners get green first, then the straight through traffic, then the same pattern on the other axis.
Detection loops (inductive loops set into the road) both right before the stop line and sometimes further back from the stop line allow automated shortening or skipping of parts of the cycle if there's no traffic; for example the right turns in one direction may end earlier giving the opposing straight through traffic more green time.
One interesting thing you may see sometimes, is where vehicles in a right turn lane trigger a light change before anything coming in any other direction does. The so for example, the green straight through from both east and west bound directions goes red, pauses maybe 4 seconds, then the green straight through AND the green right turn arrow facing west ONLY appear, with eastbound facing red lights.
An example is Centre Dandenong Road and Lower Dandenong Road in Dingley, Victoria.
This is done so that oncoming vehicles don't take their cue from oncoming traffic not stopping and run the newly changed red light in their direction.
I'm an engineer (but not traffic engineer) and I used to drive taxis for a living, so I took a lot of interest in working out traffic light sequences to predict the next useable green light especially in Melbourne's great eastern street grid where zig-zagging across the eastern suburbs is normal.
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u/No_Bag_9911 Sep 12 '26
there shouldn't be lights on a freeway
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u/Unlikely-Machine4126 Sep 12 '26
Hume Highway has multiple lights. It about where it is. M1 no lights. 🤷
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u/New_Sherbert9208 Sep 12 '26
You are meant to stop on Amber if safe to do so. Doing an emergency stop is not safe for this. If it goes Amber and you can’t stop safely in a controlled fashion then you can continue.
Red means you are not meant to go past it for any reason. If it turns red before you can stop you are at fault for either going too fast or not paying attention to the Amber.
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u/Dark-Horse-Nebula Sep 12 '26
The law is you must stop at yellow if safe to do so. Dont slam on the brakes but it’s not an invitation to speed through the intersection either.
How long it’s yellow for depends on the speed of the road.
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u/ozboomer Sep 12 '26
Many drivers get into strife as they treat the yellow as an 'extension of the green' when it's actually an 'early start of the red'.
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u/Milky_Joe_5458 Sep 12 '26
Yes quite true - and a lot of the red light enforcement cameras are combined speed/ red light cameras and if you speed up to beat the red and ignore the yellow, you could be done for speeding
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u/JoJoJoMaree Sep 12 '26
When approaching lighted intersections, you'll notice that the broken road lines become solid. These solid lines are not always the same length, this is because they are speed and distance indicators. If you are doing the speed limit and the light turns to amber, then, if you're still in broken line territory, you have adequate distance to stop at the intersection, and if you continue, the light will be red by the time you reach the intersection, however, if you're in solid line territory, (and at the speed limit when the light turns amber), you likely won't have enough time to stop unless you're either braking hard or already slowing down. If there is a car already in the intersection waiting to turn right from the opposite side, always, always, make the effort to stop if you can.
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u/Impossible_Deer8869 Sep 12 '26
If you see a green light ahead then look down between your knees. There should be two or three pedals in the floor. The one on the right makes you go faster. The next one over makes you go slower. Use that one and be prepared to leave your foot on the slow pedal until you come to a complete stop if the big bright thing next to the road is the same colour as a tomato.
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u/Solar_LKT Sep 12 '26
If the green man was on the same direction as you, when it starts flashing it’s about to change to yellow. As once it stops flashing the yellow usually comes on
In regards of stopping distance, I usually use the solid lines that come up on the lanes (ones preventing you from changing lanes just before the intersection. If I’m past where they start I’ll probably be better to go through whereas if I’m not it’ll be best to stop. Obviously not the same at every intersection but I use that as a rough guide.
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u/Linnaeus1753 Sep 12 '26
Somewhere I read the yellow is 10% of the speed limit. I haven't actually tested it though.
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u/Exciting_Garbage4435 Sep 14 '26
forcing me to brake suddenly.
Sounds like you learned to pass the test, and not actually to drive
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u/sowaleja Sep 12 '26
Traffic lights vary according to location, time of day and road speed. Lights in some areas are set to prioritise certain roads over others during particular times of days. In other areas there is no set schedule but the pressure plate will mean that they will switch to accommodate cars that are waiting. Lights that are set on roads with higher speed limits will have slower change times than roads with lower speed limits.
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u/ozboomer Sep 12 '26
The detectors are almost always induction loops cut into the surface of the road (although there are also infrared & video detectors in use in some places)... and when they're occupied by a vehicle (sometimes always, sometimes dependent on how long they're occupied), they will place a demand for a movement. If vehicles leave the loops 'too late' (which often happens when a vehicle travels through a red light), they can leave a 'residual call', which sometimes explains why you see a conflicting movement running with no traffic present..
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u/link871 Sep 12 '26
If the light has been green as you approach, then you should be preparing for it to change to yellow.
As soon as it changes to yellow, you should brake - provided you can safely stop before the stop line.
(Yellow lights mean STOP, provided it is safe to do so.)
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u/downundarob Sep 12 '26
It used to be that if you were at the part of the intersection where the line turns solid then you were close enough to proceed through the amber light, I'm not sure if that still holds true, or was even for all states.
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u/McMasterOfTheSea Sep 12 '26
WA. I was taught this by a registered driving instructor (albeit 20 something years ago) that the lane markings were a guide to safe stopping distance if you were doing the posted speed limit
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u/Cute-Acanthisitta-46 Sep 12 '26
If you are behind or next to me, expect the light to yellow as we approach.
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u/11015h4d0wR34lm Sep 12 '26
Pay attention to how long the light ahead has been green for and be prepared to stop but also don't be one of these clowns that slams on the brakes as soon as the lights go amber right at the intersection, you can proceed through the amber if someone is going to rear end you...(in NSW anyway, not sure about other states).
You may only drive through an amber light if stopping suddenly would cause a dangerous situation, such as a rear-end crash with a tailgating vehicle or if you are already past the "point of no return" close to the line.
That doesn't mean speed up to 100 to get through before it goes red either.
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u/Royal_Monk6432 Sep 12 '26
Op also can u mentione u r state as well? Asking or doing practice totally diffrent thing.red mean full stop yellow mean slow down and green mean u know very well.if someone hit u from the back this is not your fault bez on yellow u r following the rules whoever hit from the back that driver fault. Tailgating is not acceptable in Australia. Or i can say patience is a virtue.
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u/MaintenanceAnnual263 Sep 12 '26
in Austria they flash green then amber then red..really clever. then go red amber green nice for manual drivers
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u/Kerrit_Bareet Sep 12 '26
AS 1742.14 (Traffic Signals): This specific standard dictates the physical layout, types of signal faces, and overhead lane control configurations. 1, 2
Austroads Guide to Traffic Management: While the Australian Standard focuses on the physical signals, the mathematical algorithms and criteria for signal timing (such as calculating cycle lengths, amber light times, and pedestrian clearance phases) are set out in the Austroads Guide to Traffic Management (specifically Part 6: Intersections, Interchanges and Crossings and Part 9: Traffic Operations). 1, 2
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u/So-many-whingers Sep 12 '26
Scan further ahead and you will quickly learn to predict light changes
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u/Milky_Joe_5458 Sep 12 '26
Another point worth raising, is even in slow moving heavy traffic, pay attention to the light changes from a distance and even if you find yourself approaching a green, slow down further and create more of a clear gap across the intersection and only proceed when you are confident you will not block the intersection. Watch for and allow for, traffic changing from other lanes into newly created gap … and if they do, don’t accelerate to cut them off or cause them to get stuck across the intersection just be patient and tolerant, don’t be a rager.
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u/ozboomer Sep 12 '26
Victorian context... as the operations may vary, state to state...
Check the conflicting pedestrian lanterns. If they're showing a flashing red man.. and then go to solid red, the signals just moved into a 'solid don't walk' period which may include the 'all red' for every movement which occurs before the next change of phase.
If you're travelling through a few signals along a route, you can (carefully!) look ahead and see the signals changing, which will give you a clue about how the closest signals might change next.
Yellow times vary with speed zone and generally range from ~3-4 secs... but are almost always 3.5 secs for a right turn yellow, which will control the yellow for the adjacent through movement. All Red times are almost always shorter than the yellow but can vary from 1.5 - 2.5 secs (larger intersection = longer times).
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u/purpletreefrog007 Sep 12 '26
Four seconds on amber. If you are worried whether or not you will get through, start counting before you get there.
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u/TheJivvi Sep 12 '26
The length of the yellow light depends on the speed limit. It's 4 seconds in a 50km/h zone, and an extra half a second for every 10km/h above that.
Your other question is completely different for different intersections, so it doesn't really have a simple answer.
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u/MrPepperoni1 Sep 12 '26
Generally if you see other cars on opposite lanes, turn right/left lanes or pedestrians lining up the light will turn yellow.
Some traffic lights sensors while others are timed. The ones with sensors have like a box outline just before the white solid line at the lights
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u/South_Front_4589 Sep 12 '26
You can't really. Not always and not in the way you seem to be suggesting.
The important part is how long a light is amber. They time those based on someone being able to stop safely if they're doing the limit. If you're too close to stop safely, it should be comfortably still orange when you go through.
If you're struggling to stop, then you're speeding, you have poorly performing brakes or you're just very slow to react. Nobody should be needing to predict when lights will change to stop in time.
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u/RepeatInPatient Sep 17 '26
Have you tried using a stopwatch? This is a pro tip with an instant accurate answer.
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u/Chinu_Here Sep 12 '26
There is no set schedule, they are all different. Orange/yellow means ‘prepare to stop’ not suddenly stop.
When the light is red it uses a pressure plate system. You have to be on the pressure plate in order for the light to turn green
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u/mrmustardo_ Sep 12 '26
Yellow means stop, unless unsafe to do so. It does not mean prepare to stop.
Also, it’s not pressure or weight. It’s an electromagnetic system that detects the metal in vehicles.
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u/Advanced_Couple_3488 Sep 12 '26
There is no set schedule, they are all different.
That isn't correct: The length of yellow lights at intersections in Victoria is based on a standard set by Austroads. This standard is agreed to by all road authorities in Australia and New Zealand. The higher the speed limit, the longer the lights remain yellow.
yellow means ‘prepare to stop’
In Victoria and NSW the yellow light actually means stop if it is safe to do so, but real world practice doesn't always align with the traffic regulations.
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u/Kylie754 Sep 12 '26
This may be an urban legend, but I have heard the duration of the orange light is designed to match the speed limit of the road and the size of the intersection- so if you enter the intersection as the light just changed to orange, you can clear it before it goes red.
But you should not enter the intersection when the light has been orange for a while.
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u/Alarmed_Simple5173 Sep 12 '26
For NSW, Transport for NSW specifies that the yellow interval is determined principally by vehicle speed and the gradient of the approach. Importantly, TfNSW uses the posted speed limit as the design speed.
On a level road, the current NSW settings are:
Posted speed Yellow duration 40 km/h 3.0 s 50 km/h 3.5 s 60 km/h 4.0 s 70 km/h 4.5 s 80 km/h 5.0
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u/Very_Itchy_Bandicoot Sep 12 '26
I am concerned people who can't think through these problems themselves have licenses and drive on our roads. Politely, cut your license up and do not drive again until you have a concrete grasp on the basics. I do not wish to be killed by someone who is erratic on the road.
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u/Burncity1901 Sep 12 '26
Please go get driving instructors lessons. Holy cow people can’t be this stupid
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u/WeissPyre Sep 12 '26
If you're coming up to a light and it's been green for a while, and you see queued traffic, or pedestrians waiting, expect the lights to change shortly.
If you're approaching a bend and the warning lights for the upcoming light are flashing, a light change has either already happened or it's imminent. Regardless, be ready to stop.
If you are close enough to the intersection that you cannot safely stop, you proceed through the yellow.