You’re not queue-jumping, you’re helping traffic flow

It’s a familiar design at traffic lights – vehicles splitting into two lanes at the intersection, then merging back into one on the other side.

What’s also familiar is all the traffic sticking to just one of the available lanes.

In a recent debate on a Nelson-Tasman community Facebook group, one local went so far as to accuse people using the northbound right-hand lane at the Queen St lights in Richmond of ‘jumping the queue’.

It’s a similar sight at the Tāhunanui lights, where the northbound left-hand lane is often empty.

But, when asked about the design of the intersections, traffic experts say that leaving the extra lane empty is only adding to traffic woes and delays.

NZ Transport Agency Waka Kotahi system manager Nelson/Tasman Rob Service said the intersections were designed to get as many cars through the lights as possible.

“Two lanes merging into one at intersection exits are designed to maximise traffic throughput, reduce queue lengths, and make travel easier and more efficient.

“Using both lanes up to the merge point – ‘merge like a zip’ – allows more vehicles to pass through the intersection and helps prevent traffic congestion from backing up into previous intersections.”

Drivers should be using all available lane space, he said.

“This helps optimise traffic flow. Queuing in one lane creates longer vehicle queues and increases travel delays.”

Dr Urie Bezuidenhout is a Professional Teaching Fellow at the University of Auckland, specialising in driver psychology, road safety, and transport engineering.

Adding more lanes at intersections was designed to get as many cars through the lights as possible, he said.

“Otherwise, if you just have a single lane on the approach, you have a very long queue and it’s inefficient in trying to get as many vehicles as possible through the green cycle.”

Making green lights longer wouldn’t help, as it could mean too many vehicles were trying to get through, and causing a blockage at the merging point on the other side.

But, for an intersection to operate optimally it relied on people utilising both lanes, and then merging properly on the other side, he said.

When cars didn’t merge properly it forced other drivers to brake or come to a stop, which would send “shock waves” back through the traffic.

Trying to avoid the merging point on the other side led many people to stick to a single lane, but then meant the intersection was being “underutilised”, he said.

“Because no one’s using, or very few people are using, the other lane, the vehicles are queuing all the way back in the single lane … the green’s gonna run out on them.”

If people drove co-operatively and let each other merge in the zip formation it shouldn’t cause delays, he said.

Drivers in bigger cities like Auckland were better at merging and letting each other in, because they were used to sitting in heavy traffic.

“No matter where you are, you’re just queued, so you may as well just let somebody else in.”

Understanding how the system worked – and driving co-operatively – helped traffic move smoothly, Bezuidenhout said.

Drivers were often better at letting cars into slow traffic from side streets, because they were able to make eye contact.

But, when cars were in merging lanes they were singularly focused forward, he said.

“And with no eye contact, there’s no co-operation.”

He encouraged drivers to act co-operatively by using all the available lanes – and then merging properly on the other side.

“If everybody utilises the spare capacity better, then everybody gets through faster and easier with less frustration.”

By Warren Gamble, Nelson Mail