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Thursday, April 25, 2024

Let There Be Lights – Prime Mover Magazine

Pacemaker lights have been installed by Transurban in the upgraded Burnley Tunnel.

If you’ve come out of the Burnley Tunnel recently and felt like you’ve been subjected to a light show, rest assured, your mind is not playing tricks on you. Transurban is.

Anyone in a car or truck is likely to have noticed the pulsing lights inside the tunnel that follow vehicles as they ascend the steep incline.

That incline is important. At a gradient measured at 5.4 percent it is proving an obstacle for flowing traffic which is, despite the speed limit of 80 km/h, falling on average to 65 km/h at the point of departure.

It’s something of a crucial factor when traffic ideally, by then, should be flowing into the Monash Freeway.

Instead, a bottleneck occurs, as drivers collectively resurface from a depth of 65 meters below the Yarra River, are failing to maintain their entry speed.

Despite being a three-lane asset, the Burnley Tunnel, which was built in 1999, has had congestion problems for years primarily because of this 1-kilometer-long incline.

The problem with infrastructure, according to Phil Naulis, Transurban General Manager Operations, is complexity. As the Burnley sits in a particular part of Melbourne where two lanes feed in from the right hand lane there are limitations as to what can be achieved.

“Whenever you force vehicles to shift and change lanes you cause a congestion problem,” says Phil. “We’re not going to add an extra lane.”

Trucks make up 12 percent of Burnley traffic. Calls for all trucks to be banned from the right hand lane, proposed by some talkback radio shows, simply won’t work as a measure to alleviate congestion.

Pushing all the heavy vehicles out of the right hand lane would, according to Phil, only create more congestion at the merger site and further downstream from the entry point on the right.

“There’s additional complexity that comes with that,” he says.

Changes to the environment, in short, have been predicated on overcoming a slope, which is highly problematic, given it historically reduces the capacity of the tunnel.

The challenge for Transurban was to find extra capacity that it could invest in knowing that infrastructure, once built, can rarely be modified. As a consequence, it went in search of other examples around the world living with this particular problem.

At a conference in Bordeaux, they soon found it. A team from Tokyo had a fungible stumbling block with an identical gradient and a not dissimilar outcome. Drivers were slowing down resulting in congestion.

The Japanese presented the traffic statistics both before and after they implemented their pacemaker light system, a pulsing light now familiar to road users in the Burnley Tunnel that goes down the road at a set speed.

It was for Transurban, what the old timers call a major development. But with the onset of COVID lockdowns preventing the Melbourne team going to Japan to learn more, they were forced to localize their evaluation. Fortunately, Transurban has a large customer base, enabling it to draw upon a large volunteer group.

These volunteers were, when the time came, covered in heart monitors and eye trackers. As they drove into the tunnel Transurban recorded their experience.

Following this, Transurban created the tunnel as they wanted it to be and as it is now in virtual reality and drove through it, as part of a trial, again in VR.

What they were looking for was correlation of the data out of Japan.

The Japanese data confirmed it by showing Transurban the benefit of having a flickering fast moving light in the tunnel. Why is that you might ask? Studies have shown that humans are preconditioned for fast moving peripheral movement.

“If someone is coming up on your periphery we are preconditioned to catch up or get away from it,” says Phil. “We almost can’t help ourselves.”

Lighting design in tunnels, however, is highly regulated. For one, single points of flicker in a tunnel are considered taboo.

A huge amount of work was therefore necessary in design alterations.

Transurban’s safety and human factors teams were engaged to help overcome this problem.

Upgrade works included deep cleaning and repainting of the tunnel walls, repairing barriers and installing colorful, more energy-efficient LEDs — 8000 LED segments to be exact.

“One of the things we found from our studies was the tunnel is too dark regardless,” says Phil. “Yes, they met the design standards in 1995 but those are not the operating standards in 2023.”

Phil Naulis speaking at the VTA State Conference.

Part of the lighting process involved changing the walls to white with a particular reflectivity.

White throw on walls has been modified, in fact, to make it feel even whiter. Entry portal treatments were treated to make the interior much brighter on approach.

“We’re using technology and science to overcome bulk driver behavior,” says Phil. “We’re trying to influence the entire traffic stream, not one driver.”

The pacemaker itself will run to a maximum speed of 80 kilometers per hour and a maximum differential speed of 15 km/h. There are six sets of sensors all the way through the tunnel.

The sensors detect the average speed of each of those points. The pacemaker is then set to run relative to that detected speed to a maximum differential of 15 km/h.

“It will run 15 km/h faster than the slowest speed we’re going to have in there and it will regularly accelerate all the way to the end of the tunnel,” explains Phil. “What we’re trying to overcome is that exit speed of 65 km/h.”

The green pacemaker lighting encourages drivers to maintain a consistent speed through the Burnley Tunnel, particularly on the uphill segment before the exit where traffic most often lags.

Drivers won’t need to do anything differently as the green band of moving light provides driver peripheral vision a marker to keep pace.

The pacemaker lighting operates 24 hours a day, seven days a week and will move at a speed safe and appropriate to traffic conditions, while never exceeding 80 km/h.

In the event of an incident in the tunnel, the lighting will switch off. It will resume only after the road is safely cleared and all three traffic lanes are operating.

Internally at Transurban the pacemaker lights are the outcome of a project known as One. The numerical reference in the project title is about shifting the dial one percent.

“This is about incremental gains using technology to improve capacity,” says Phil. “So, we’re looking at a way of addressing the behavior characteristics of drivers to create a one percent shift in traffic.”

At the time the Burnley and Domain tunnels were built, Melbourne was the recipient of world class technology. In 1999, when the tunnels were first opened to the public they were considered cutting edge given they were the first multilane free flow assets in the world according to Phil.

“What we are doing now is turning Burnley back to its heritage of world class assets,” he says. “We are changing the way drivers interact with the Burnley tunnel.”

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