The time needed to commute across Canberra during the morning peak at the height of coronavirus restrictions fell dramatically, with travel time on the Barton Highway dropping by 14 minutes in March.
Data collected by Roads ACT showed traffic volumes on the city's arterial roads dropped about 40 per cent as the government told people to avoid non-essential travel and employers encouraged staff to work from home.
The number of cars has again started to increase as restrictions have eased and more people return to work and school but the ACT government hopes a larger long-term surge in car use can be avoided.
Transport Minister Chris Steel said the government would continue to encourage walking and cycling, as well as a staged return to mass public transport use.
"Transport Canberra is preparing a public transport recovery plan that will work on how we build confidence in public transport, beyond hygiene measures, as we come out of the pandemic," Mr Steel said.
If commuters continue to drive to maintain social distance rather than take public transport, road congestion could quickly return to levels higher than before the pandemic.
The Roads ACT assistant director of traffic signals, Chris Bunnik, said the decline in road use during the pandemic had been unprecedented and showed only a relatively small number of cars during the peak needed to be taken out of the network to significantly reduce travel times.
"Who would have thought travel in a peak period could reduce so much," Mr Bunnik said.
"Basically, we're looking at off peak type volumes through peak periods. Once you get away from teetering close to that capacity level, it's amazing to see the travel times you can achieve," Mr Bunnik said.
"A lane might take 1800 to 2000 vehicles an hour roughly. Once you get one more car than that capacity, that's one car in a queue. But if you double that, you've got two cars, you've got two car queues."
Mr Bunnik said small reductions in the overall number of cars could make a large difference to the overall commute times.
By removing 10 per cent of cars from the peak, the remaining cars could see their travel time drop by 50 per cent or more. "That's where you see the real volatility in your daily commute. It only takes a very small fluctuation in vehicles on the road to actually have a significant impact on congestion," he said.
Mr Bunnik said the data would be help model demand growth on the ACT road network.
Travel time in the morning peak period on the Barton Highway fell from about 20 minutes on March 4 to six minutes on April 1, while Parkes Way saw a reduction in travel time from 15 minutes to six minutes.
Afternoon peak travel times on the Barton Highway fell from eight minutes to five minutes in the same period, while Parkes Way saw travel time fall from 11 minutes to six minutes between March 4 and April 29.
Between March 18 and March 25, traffic volumes measured at key intersections - which are identified to give an overall picture of the city's road network - recorded a 39 per cent drop.
The number of cars on the roads has increased slightly in March, but the road network is still running at 70 per cent of its usual volume, the Roads ACT analysis found.
Mr Bunnik said the ACT's traffic signals had adapted well to the decreased amount of traffic but some manual tweaks had been made.
He said the introduction of automatic switching for crossings, meaning pedestrians would not need to touch the button to signal their intention to cross a road, would be reviewed on a case-by-case basis as the pandemic eased.
"Some of these movements we can get away with it at the moment because generally the traffic volume is down so the impacts are a lot less. It's something that we need to review as traffic builds up once again. We certainly see pedestrian amenity as a very high priority. It's really about keeping that balance between pedestrians and vehicular traffic," he said.
After Canberrans were encouraged told avoid peak hour public transport in mid-March, patronage fell by 20 per cent.
A national survey conducted by the Institute of Transport and Logistics Studies at the University of Sydney found 84 per cent of people considered travel by car the most comfortable option.
The institute's Associate Professor Matthew Beck said this suggested public transport hygiene concerns could lead to more private cars on the road as workers returned to their offices.
Data collated by Google showed movement across ACT retail spaces fell by 40 per cent in March.
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