Adelaide City Council could save millions in future construction costs — and congestion would be reduced — by allowing people to park their motorbikes and scooters on footpaths, a traffic engineer says.

The council would save $125 million in the foregone cost of building 5000 new car parks if that number of motorbike and scooter riders were able to choose the footpath instead, according to an analysis by traffic engineer James Edwards for consultancy firm InfraPlan.

Edwards said it would cost around $25,000 to build each new car park space into the future, and – assuming continued growth in the number of cars  on Adelaide roads and therefore a need for more car parks – the council would save millions by not having to build them.

Adelaide City Council administration is currently investigating the merits of allowing the vehicles to park on city footpaths.

“The demand for motorcycle parking is outstripping the supply,” said Edwards.

“The currently available on-street motorcycle parking is full every weekday and full early (and) we would prevent spend by providing alternatives.

“To those that have to use a car, there are more car parks available.”

Edwards’ paper spruiks the benefits of motorcycles and scooters taking up less space on the road — more people in these vehicles rather than in cars would reduce congestion, he argues — costing less money and emitting less greenhouse gasses.

“By allowing motorcycles to park on the street, there are all these other flow-on effects,” said Edwards.

“You’re dealing with a more space-efficient vehicle.

“Given that the vast majority of cars coming into the city are single occupant, if we can convert a number of people from driving a car to riding a motorcycle then there is some space saving on the road, and therefore congestion can be relieved.

“For businesses that are running business vehicles, there are tax concessions available for the purchase of business vehicles, and rather than that concession covering half the cost of a small hatchback, it could potentially cover the full cost of a scooter.”

The state government would have to change road rules to allow on-footpath parking.

A spokesperson for Adelaide City Council said the administration was aware of the discussion paper and “we will look into it further”.

There are currently 455 free motorcycle/scooter parks in the city, and 54 paid motorcycle/scooter spaces undercover in U-Park buildings.

Regarding building new car parks, the spokesperson said: “Council continues to work towards providing people with more transport choices such as public transport, cycling, car sharing etc, as well as managing our current parking supply more efficiently using smart technology”.

Melbourne is the only capital city in Australia that allows motorcycles and scooters to park on footpaths.

“Their experience has been positive,” said Edwards.

“It hasn’t attracted unsavoury elements to the city.”

In that city, motorbikes and scooters can park on footpaths, subject to restrictions: they cannot be parked on private property or opposite disabled parking spaces, nor can they park near street cafés, post boxes, rubbish bins, man holes, taxi ranks, designated no-parking zones or public transport stops.

Despite the benefits though, Edwards acknowledged there may be safety risks if large numbers of people swap their car for a scooter or motorcycle.

He said there may have to be increased licencing and training requirements, and possibly a driver awareness campaign, to deal with a possible jump in scooter and motorcycle numbers if footpath parking were made legal.

However RAA city manager for road safety Charles Mountain said he was not concerned about an increase in scooters and motorcycles on the road.

“It’s something that we support being looked at,” he said.

“Where you’ve got wider footpaths and it wouldn’t impede the normal pedestrian walkway, then yes it could happen (but) if you’ve got situations where you’ve got a lot of outdoor dining and busy pedestrian activities then it may not be appropriate.

“It tends to work reasonably well in Victoria.

“They’ve got quite a good code of conduct available which lays out … what can and can’t be done.

“There would need to be a guideline or code of conduct (in South Australia).”

Lord Mayor Martin Haese proposed allowing motorcycles to park on footpaths during his election campaign in October, provided that any safety concerns were thoroughly considered and pedestrians, public transport, deliveries and other movement would not be obstructed.

Over 200 of the free motorbike/scooter parks in Adelaide’s CBD have been added since council administration began reviewing all on-street parking areas in 2008 to identify opportunities for additional motorcycle parks where available space is too small for a car.