Intersections and roundabouts

Traffic signals run on a sophisticated system, called SCATS. This constantly assesses how many vehicles are travelling through the intersection in each direction. The system then adjusts the length of the green light to compensate. This ensures queuing and delays are minimised.

Many intersections are also linked to adjacent intersections along a major traffic route. The timing of the signals is then governed by creating the best traffic flow along the route.

You may regularly turn right at an intersection and ‘know’ that, for example, approximately six cars will get through on the green. However, at another time of day this will differ. And on a different day of the week this may also change, because traffic conditions have changed.

The system also gives priority to trams and buses at some intersections. While some motorists might not appreciate this, giving these mass-transit modes priority reduces congestion by encouraging people to use public transport. In some locations, pedestrians may also get a longer crossing time where many people cross, or slower pedestrians are present. This may also change the length of green time you receive at the intersection.

Ever approach an intersection where the red-turn arrow switches off and no green-turn arrow is displayed? Don’t worry – it’s not a glitch!

In this scenario, the red arrow indicates that it’s not safe to turn just yet. When it drops out, it’s letting you know that you might be able to start turning, but you need to watch the remaining traffic lights and be mindful of oncoming traffic before you go. If the remaining light is green, you may start to turn right, just as you would at an intersection without arrow lights.

At some intersections once the arrow drops out there are no other traffic lights. In this case, you can start to turn after giving way to other road users.

Some freeway entry ramps are controlled by lights to make merging safer and easier by spacing out vehicles, known as ramp metering. Some operate 24/7, while others only switch on during peak-traffic times. Here’s how they work:

• When the lights start to operate, the yellow light flashes for around one minute.
• The lights then turn red for drivers on the entry ramp to stop at the stop line.
• The lights then begin their green, yellow and red cycle.
• The red traffic light means drivers must stop and not proceed until the light turns to green, just like standard red traffic lights at intersections.
• Only one vehicle can enter the freeway from each lane, unless signs state otherwise.
• Some freeway ramp signals allow trucks or vehicles with two or more people (T2/T3) to bypass the lights for priority access onto the freeway.

First things first – don’t panic! When the lights are out, flashing yellow or just not working properly, simply approach the intersection with caution and courtesy, giving way to any vehicles approaching from the right. If you’re turning right, remember to give way to both oncoming traffic and traffic on your right.

When it’s safe to, you might also want to report the problem. You can do this by:

• locating the pale green or grey box at the side of the intersection and noting the intersection identification number, and
• calling VicRoads on 13 11 70 and quoting the identification number.

Drivers’ behaviour suggests they think of the yellow light as an extension of the green, rather than as a warning to stop at the imminent red. A better way to think of the yellow is that it is at the start of the red, not at the end of the green.

A yellow light is not a signal to travel faster through the intersection to beat the red light. You must not travel through a yellow traffic light if you're able to stop safely before the stop line. If you can’t safely stop before the stop line, you must stop before entering the intersection itself.

If you’ve already entered the intersection when the light turns yellow or red, you must exit the intersection as soon as you can safely do so.

Keep in mind, just because you’ve crossed the stop line, does not necessarily mean you have entered the intersection. At this point, our recommendation would be that you stop.

Check out our Youtube video on Traffic Lights for more.

The traffic and environment should be considered when deciding if it’s safe or not to stop. Learner drivers should exercise caution, learn to anticipate light changes and prepare to stop rather than prepare to race through.

RACV receives many calls regarding red light camera infringements. Much of the time, the driver has decided they can continue through the intersection on the yellow light, misjudging either the traffic speed, the length of time it takes to get to the stop line or the length of the yellow light.

The trigger for a red light camera is located just over the stop line and is activated 0.5 seconds after the yellow light changes to red. So in order to get a red light camera fine, you have not stopped during the yellow and have gone through the red half a second too late.

Do not block the intersection

If the traffic ahead has not cleared the intersection or there is not enough room for your vehicle to reach the other side without blocking the intersection, do not enter the intersection.

By blocking the intersection, drivers delay traffic including emergency vehicles as well as risk substantial penalties. Watch our video on blocking an intersection for further information.

It’s allowed, but only when line marking permits it and it’s safe to do so. Remember to indicate as you normally would and allow enough distance to avoid collision or obstruction to other vehicles.

We often receive feedback that the rules for exiting a roundabout in NSW, QLD and SA are different to Victoria. While some Victorian road rules are different, when exiting a roundabout, they’re similar – indicating is required.

Here are the key things to remember:

• Before entering, indicate as you normally would – left to turn left, right to turn right, no indicator if you’re going straight.
• When you exit the roundabout, indicate left if practicable.

If you’re leaving the roundabout more than halfway around, indicate right. Halfway around is defined as leaving on a road that is substantially straight head from the road you entered on.