However, opposition parties criticised a delivery plan being delayed until next year before of budget uncertainty.
Maps published in the final Strategic Transport Projects Review 2 (STPR2) also include “bus rapid transit” routes into Edinburgh and the possible conversion of rail lines in Glasgow to tram/light rail as part of the city’s Clyde Metro scheme.
The tram would go as far as Queen Margaret University in Musselburgh, while Newbridge on the west side of the city was part of the original tram line proposals 20 years ago.
They come on top of a proposed Granton to Dalkeith tram line via the city centre, which is due to be considered by Edinburgh councillors early next year.
The Edinburgh plans in STPR2 would form part of a “mass transit” system for the region, which is aimed at cutting journey times by reducing the need to change services.
It would focus on the most popular routes where buses are delayed by congestion caused by other vehicles to make them more attractive for drivers to switch from their cars.
Bus rapid transit routes shown include to Musselburgh and Cockenzie in the east, Penicuik in the south, a loop to Livingston taking in Heriot Watt University and Newbridge in the west and as far as Dunfermline to the north.
In Glasgow, which already has Britain’s largest urban rail system outside London, the STPR2 map shows potential new Clyde Metro routes into the the city centre from Glasgow Airport, East Kilbride, Newton Mearns and Newton, and six from the north of the city including Kirkintilloch. Some could use derelict rail tunnels.
Another would link Clydebank with Paisley via a new Clyde crossing at Renfrew and on to Barrhead, with a further line to Erskine. Some rail lines could be converted to metros, including the Cathcart Circle on the south side, and the Milngavie route.
Transport Scotland said the system would be a combination of segregated lines and those running on streets like trams, with priority given to unserved areas of the city.
City of Edinburgh transport convener Scott Arthur said: “The inclusion of the potential to extend the tram line to neighbouring authorities is welcome and signifies the Scottish Government’s willingness to support us to explore these opportunities. We have committed to the expansion of the mass rapid transit network, providing sustainable, high-capacity transport options.”
Glasgow City Council leader Susan Aitken said: “A Clyde Metro can help us address the climate emergency by delivering clean and net-zero carbon connectivity, whilst also providing the affordable, sustainable and integrated public transport system our citizens deserve."
But Scottish Conservatives transport spokesperson Graham Simpson said: “This long-awaited report is nothing more than a damp squib. Once again, they are letting down motorists and communities right across Scotland by kicking much-needed road upgrades and transport improvements into the long grass.”
Scottish Labour counterpart Colin Smyth said: “The cost of commuting is through the roof and transport emissions remain one of the biggest threats to our climate targets, but the SNP-Green government has kicked all the big questions down the line yet again by failing to publish a delivery plan.”