The Go Bus Transport depot would need to shift from Princes St if the site was sold by the Dunedin City Council to enable Kainga Ora to develop housing.
Kainga Ora has yet to make a call on whether it should proceed and, in the meantime, Dunedin Tramways Union branch president Alan Savell highlighted advantages of the site as a bus depot.
"Foresight and wisdom over a century ago, upheld by the last 30 or more city councils, has placed the city’s bus depot at the heart of the city’s bus network," Mr Savell said.
It sat alongside nearly all of the city’s bus routes and that made it ideal for both driver and bus changeovers, he said.
"On frosty mornings when the city is covered in ice, miraculously the depot and its buses usually start the day frost-free.
"Clearly our ancestors knew what they were doing choosing this site."
The Go Bus Transport company has occupied the Princes St site in recent years, but a lease from the council expired in March 2017 and a periodic tenancy has been in place since.
Kainga Ora has been been looking into the Princes St site’s potential for housing since winter last year and a decision about the potential purchase is expected to be made soon.
It is understood the former PlaceMakers site in Portsmouth Dr in South Dunedin is a possible site for a relocated bus depot, after the trades business shifted to the former Carisbrook sports ground.
A possible shift of the depot could happen before up to $6.4million is spent by the council and Waka Kotahi NZ Transport Agency upgrading the Princes St corridor, in part to make it more suitable for buses.
It is expected a proposed design for the corridor will be consulted on in the first half of next year.
Mr Savell said if the depot was moved, there would be more downtime and buses would be empty for longer.
"Drivers will have to start their days even earlier, due to lengthened empty runs to start each route," he said.
"More drivers will be needed to cover the existing level of service due to these inefficiencies."
Bus companies have been battling to find enough drivers to run Dunedin services, amid driver illness and a national shortage of drivers.
Mr Savell said the Princes St depot buildings were not fit for purpose, as they were "old and riddled with asbestos".
They needed to be demolished, whichever option was pursued, he said.
The depot was big enough that it could accommodate all the buses of all contractors, he said.
Mr Savell said the union supported public housing — "many of our drivers live in social housing right now".
However, he said it mattered more where a bus depot was located than where exactly social housing was built.
