Every fourth vehicle coming into Melbourne during peak hour in 2020 will be a bicycle under a plan that has been branded “ambitious but achievable” by cycling groups.

The City of Melbourne bicycle plan, released on Thursday, aims to increase the number of cyclists in the city each morning from 12,000 to 20,000 in four years by promoting the network of bike paths, improving connections to bike paths along major cycling routes, and physically separating bike lanes from motor vehicle traffic.

It also aims to increase the number of public bike parking spaces from 800 to 2,000 and eliminate the number of fatalities and serious injuries from bike crashes by moving cyclists away from parked cars and redesigning intersections, including introducing new traffic signals for cyclists that would allow them to take off first.

The lord mayor of Melbourne, Robert Doyle, said the number of cyclists in the city had almost doubled since 2008, an increase he attributed partly to improved cycling infrastructure.

The plan includes investigating a possible second east-west connection for cyclists to run south of the city, complementing the Latrobe Street bike lanes on the northern edge of the CBD, and suggests planning work begin on separated bike lanes in St Kilda Road as an “immediate priority”.

Both those projects would have to be done in conjunction with VicRoads and the state government, Doyle said.

St Kilda Road already has one of the highest densities of cyclists in the city; bicycles made up 30% of vehicles during peak hour in 2015, according to the report. In the city as a whole, bicycles made up 17% of peak hour traffic in 2015, up from 11% in 2012.

The road with the most bikes on any given morning was Royal Parade, coming in from the northern suburbs, where bicycles made up 35% of vehicles. But the busiest cycling route was the Yarra Trail, a mixed-use path that enters the city from the east.

The chief executive of the Bicycle Network, Craig Richards, said Melbourne’s plan to make bicycles 25% of morning traffic was “ambitious but achievable”, provided the city could encourage more women to ride.

According to figures from Bicycle Network surveys, the percentage of morning cyclists on Swanston Street increased from 26% in 2011 to 39% in 2014, and Richards said the key to growing that figure was improving bike paths.

A fear of injury was cited in the bicycle plan as the main reason people didn’t ride, although crash statistics show the number of accidents had remained steady at an average of 240 a year, while the chance of any individual cyclist being involved in a crash had reduced by almost half.

“The decision to invest in separated lanes in Albert Street, and to make separated lanes in St Kilda Road a high priority, will result in many more women riding bikes into the city,” Richards said.

However he said any new paths should be designed on the assumption that the number of cyclists would continue to grow at an increasing rate. Already, he said, paths such as the Yarra Trail were so overcrowded that some commuters preferred to ride on the road.

“Governments of all kinds should be looking into the future and building the bike infrastructure now that we are going to need in the future,” Richards said.

Boyd Fraser, a spokesman for volunteer cycling advocates Beach Road Cyclist, said the cycling plan, while praiseworthy, didn’t address some of the major concerns of cyclists, including legislative change to introduce a minimum passing distance and demerit points for drivers who open their car door on a cyclist.

“The solution is not just in upping the number of bike paths that we have and improving some existing ones, it’s more complex than that,” he said.

“And if you are going to introduce improved infrastructure, you don’t want it being put down in a haphazard manner.”

Fraser said that even with the improvements outlined in the plan, Melbourne was a “long, long way off” matching cycle-friendly cities in Europe, and still had pockets of “anti-cyclist sentiment”.

One of Melbourne’s most popular cycling routes, Yarra Boulevard in Kew, is regularly peppered with metal tacks that can cause puncture-related pile-ups.