Using computer modelling of mixed scenarios, engineers found dedicated lanes significantly improved the overall safety and traffic flow in a hybrid network of pedestrians, cyclists, automated vehicles and legacy vehicles.
At the same time it could be difficult to persuade road users to give up space in an already congested road network, especially in cities such as Sydney and Melbourne.
But lead author Dr Shantanu Chakraborty from UNSW School of Civil and Environmental Engineering, said if the road and transport network is not prepared for these vehicles when they enter the market, it will significantly hinder the travel experience of all road users.
“Traffic congestion costs the economy billions of dollars every year in all the extra time spent commuting,” he said.
“The proposed model will help minimise interaction with legacy vehicles and reduce overall congestion on the road.”
“The mix of autonomous vehicles and legacy vehicles will cause issues on the road network unless there is proper modelling during this transition phase.
“If we get caught out and we’re not ready, we won’t reap the full benefits of the technology behind these autonomous vehicles.”
Dr Chakraborty concedes however that adding an exclusive lane for autonomous vehicles means removing a lane from legacy drivers.
So this “may cause a little disruption”.
“If you look at our existing network, we already have something similar with dedicated bus lanes – so we’re not reinventing the wheel here,” he said.
“Freeways are also the best network of car lanes to trial as they have dedicated entry and exit points where drivers can automatically switch on and off their automated features.”
On a more positive note, autonomous vehicles not only have the potential to provide cost-effective mobility options, but road users can also reap the benefits of reduced congestion.
Dr Chakraborty says road users can activate the autopilot features of their vehicles while they are in these exclusive lanes.
Automation means traffic flow would significantly improve in these lanes as drivers are not solely relying on their attention and reaction time to traffic conditions.
“Say you’re sitting in traffic and the traffic light turns green, the driver doesn’t instantaneously take off that second; there is usually a response time before you press on the pedal and the car moves,” he said.
“Then the driver behind you reacts and so forth and by this stage, there has been some time passed.
“However, with autonomous vehicles, the movement is more coordinated because the vehicles are fitted with sensors.
“When the signal turns green, all the vehicles move simultaneously which will improve traffic flow and reduce congestion.
Dr Chakraborty said variable signboards could be used to change lane designation based on the traffic conditions.
This means during peak hours, roads can be used more efficiently.
“Our modelling accounts for changing traffic conditions. For example, during non-peak hour times when we don’t need a lane for autonomous vehicles, we can have all lanes open for legacy vehicles,” he said.
“Due to the minimal infrastructure, our proposed model also has the potential to design ramp metering for freeway networks to help regulate the flow of traffic during peak hour.”
But how can we ensure drivers of legacy vehicles will not misuse the new lane system?
“Similar to existing high-occupancy lanes, for example, transit lanes or T2 or T3 lanes, we can apply a fine when drivers of legacy vehicles enter lanes dedicated for autonomous vehicles,” he said.
“Like any other road rules, we can only trust that drivers obey the signs and road rules.”