Frustration erupts at notorious Aussie intersection over 'one second' green lights

Yahoo

07-04-2025

Confusion has erupted after footage surfaced of a traffic light at a notoriously congested Australian intersection switching from red to green — and back to red — in just a second or two.
It's no secret to anyone living in Sydney's metro area that the Rozelle Interchange, in the city's Inner West, is known for its heavy traffic. Despite the spot having recently received a major upgrade, it can still be tricky to navigate, particularly during busy periods.
In the video, dashcam footage shows a driver waiting at a set of lights in the right lane, hoping to merge into traffic flowing onto the Anzac Bridge from the western entrance. Just one to two cars make it past the lights as they quickly flicker from red to green, and red again, with the video ending before the driver is able to get across.
Hundreds of people responded to the footage, many sharing their surprise at the speed of the change. Speaking to Yahoo News Australia, Professor of Urban Mobility at Swinburne University, Hussein Dia, explained the concept is actually one employed in many parts of the country to limit congestion, particularly on motorways known for their bottleneck-like conditions.
Referred to as "ramp metering", the system is a "key component of managed motorway operations", Dia said. It uses "coordination principles to reduce congestion and potential for conflicts, as the traffic from the on-ramp joins the main motorway lanes", he explained.
"You can see the traffic merges near the horizon in the video."
The idea is that heavy traffic entering from on-ramps can cause congestion at merge points on the main motorway. Ramp signals work by monitoring traffic flow and timing vehicle releases from the on-ramps to ensure a smoother, more efficient merge.
"Usually, one vehicle is released per short cycle," Dia said. "They are implemented in many cities around the world to help ease congestion and improve safety. The ones running in Victoria have very sophisticated coordination algorithms."
In fact, Melbourne's coordinated ramp metering system — part of the broader Managed Motorways strategy — uses real-time data from sensors embedded in the road to dynamically adjust the rate at which vehicles are released.
This helps to prevent bottlenecks, maintain smoother traffic flow, and reduce stop-start driving, which in turn can cut travel times and improve fuel efficiency. Studies have shown that when implemented well, ramp metering can significantly improve freeway performance, with Victoria considered a national leader in this space due to its use of integrated technology and system-wide coordination.
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Online, motorists shared their thoughts on the system.
"It's ramp metering. It limits the amount of traffic that can merge to prevent the main arterial route from clogging up and slowing down," one person said. Do they work? Absolutely. Does it suck having to sit in stop-start traffic for a while? Also absolutely."
"I am kinda surprised that OP hasn't experienced these before, mustn't head out west often, at least not in peak times. They do work, sometimes. The issue I have with them is they still don't help those who shouldn't be driving on motorways to merge," said another.
"They do work if people use them properly. I drive all day around Sydney and there's always the idiots that just ignore them and sail on through," commented a third.
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