An extended and upgraded Frome Street bikeway would reap millions of dollars in public benefits for Adelaide, a new cost-benefit analysis has found.

The Adelaide City Council administration analysis shows that the city could earn up to $15.5 million over 30 years in economic and social benefits by making minor upgrades to the existing bikeway, and rolling out a high-end bikeway extension towards North Terrace and beyond.

The report contains several options for the bikeway but recommends minor changes to the existing infrastructure and that it be extended beyond North Terrace. The current bikeway runs from Carrington Street to Pirie Street.

Implementing these recommendations would cost ratepayers around $10 million. According to the analysis, every dollar spent would reap between $1.20 and $1.90 in benefits.

While the report recommends only minor changes to the existing bikeway at an estimated cost of $90,000, Lord Mayor Martin Haese told InDaily he supported returning the street to two driving lanes in each direction.

Haese’s preferred option for the existing bikeway would cost $5.6 million, and includes a suite of upgrades to the streetscape, in line with the principles of the Adelaide Design Manual.

It would feature:

• Four lanes of traffic during peak times.
• Two lanes of traffic and parking/loading during off-peak times.
• A kerb-side separated bike path in each direction, using a cement median to protect cyclists.
• “Moderate opportunity” to increase street trees and landscaping.
• A small increase in the width of the footpath area, providing “limited” opportunity for additional outdoor dining.
• High quality paving and street furniture.

Returning the number of driving lanes to four, however, contradicts the recommendations of a previous expert report, which found that doing so would have a negligible impact on traffic flow.

Haese said it was worth the higher cost to create a streetscape that could be supported by all stakeholders.

“Yes it will cost more money – yes it will – but I would argue, we do it once and we do it right,” Haese told InDaily this morning.

“This is the way and the means for ensuring that we do get widespread support (for the Bikeway).

“It also will bring much, much broader acceptance among all stakeholders.

However, he said: “I wouldn’t say it’s a political solution”.

“We have what I believe to be a profound opportunity here to lay down some public infrastructure between Carrington Street and North Terrace and … down to the River at some point in time,” said Haese.

“We need to move beyond arguably what has been fairly short term thinking (and) put down high-quality point-to-point public infrastructure along that stretch.

“I don’t want to see a quick fix.

“If we can get this over the line … this is really something that all of Adelaide can be proud of.”

Earlier this year, a majority of councillors indicated they would not support more than minor changes to the existing separated bikeway.

A previous version of this article stated an estimated public benefit of between $25 million and $45 million from the extension and upgrade of the bikeway. Council administration later clarified that the Net Present Value of the proposed changes – up to $15.5 million – which subtracts capital costs, is the correct figure.