Commuters along Adelaide's longest tram route are facing the prospect of having to rely on alternative means of transport for up to nine months, as overpass construction work is carried out.
Two tram level crossings along the Adelaide to Glenelg line will be removed and replaced by an overpass above Cross and Marion roads, at a cost of $400 million jointly funded by the SA and federal governments.
A new tram stop will also be built between the roads, and will include lifts and stairs.
SA Transport Minister Tom Koutsantonis said the current boom gates impeded traffic for up to 20 minutes each hour during peak times, when as many as 30 trams passed through.
"We promised we'd remove one of the worst intersections in South Australia — the tramline over Marion and Cross [roads] interferes with about 50,000 cars a day," he said.
The government today released further details about that plan and its impact on passengers, revealing that the line would be closed for six-to-nine months to allow for construction.
Work will begin in May next year, and substitute buses will run during the line closure.
"[This] is a major piece of work, but of course that will mean we'll have to have the tram out of action," Mr Koutsantonis said.
"We've set our aim at six-to-nine months for a tram closure; obviously, the works will take a lot longer than that."
Transport Department chief executive John Whelan said the exact timing of the project and other details, including where the trams would be kept when the Glengowrie depot becomes inaccessible, were still being worked out.
He said trams through the CBD, to the Royal Adelaide Hospital and Adelaide Entertainment Centre, were not likely to be impacted — but that several properties would be compulsorily acquired.
"It's not all doom and gloom, the whole line won't closed," he told ABC Radio Adelaide.
"We are very confident we will be able to run trams from around the parklands, through the city through to the Entertainment Centre.
"There's only about three properties [being acquired] for the actual construction of the tram overpass. Being able to close that tramline temporarily has enabled us to minimise land acquisition."
Mr Whelan said trees would be removed, but the project would result in a net gain of trees, with more planted than cut down.