City councillors will get their first chance to examine the confidential final business case today (8) at a “special data room” at City Chambers - before the full council decides whether or not to approve the extension on 14 March.

If the extension is approved by councillors, the works should be completed by 2022 and operational in the first quarter of 2023. In the first year of operation, the council predicts 16 million passengers will use the line.

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Controversial plans to take trams to Newhaven will carry a £207m price tag.

Although the details of the final business case are not being revealed to the public until it is considered by the transport and environment committee on February 28, the council says it can be built within a budget of £196m. But councillors will be asked to approve an overall budget of £207.3m to include a recommended six per cent level of “optimism bias” to take account of an increased risk buffer for any problems encountered. An initial assessment of the extension was predicted to cost a total of £165m.

The delayed original tram line was opened in 2014 and cost £776m for a shortened route - more than double the original budget. The estimated final costs of the inquiry into the crisis is expected to rise above £10m.

Council leader Cllr Adam McVey said: “Edinburgh has a fantastic public transport network but we need to extend the tram to build on our first-class, fully-integrated transport system.

“The final business case before us now is the result of a huge amount of work by the project team to produce a strong business case for taking trams to Newhaven which – crucially – does not divert funding from other council services.”

He added: “Having developed the case further and gone through the tender process, we now have much greater certainty of the total project cost – following industry guidance, learning the lessons from the previous project and taking a thorough, diligent and prudent approach to risk management. We will work to make sure the timelines and costs in the final business case are met.

“All councillors will be taking the opportunity to examine in detail the final business case and associated documents in detail so that we can collectively make as informed a decision as possible come 14 March. If the council moves ahead with this project, we’ll be working hard to make sure we deliver this project on time, on budget.”

The project will be funded through borrowing paid back by future tram fare revenues, along with a special £20m dividend from Lothian Buses.

As well as the council taking more risk into account following the problems with the first phase of the tram project, market pressures partly led by the downfall of Carillion have added to the projected construction costs.

Taking into account lessons learnt in the first phase of the tram project, construction is planned using a “one-dig” approach - closing each work site only once and opening them again only once all works are complete.

Depute council leader, Cllr Cammy Day, said: “A tram to Newhaven would not only provide a direct link for the people of Newhaven and Leith to the city centre and out to the airport, but would connect residents and visitors to major employment and travel hubs along the route.

“Through tireless public consultation to hone the designs, respond to concerns, explore solutions and develop measures to ensure a lasting positive legacy for the whole area, we’ve managed to arrive at a final set of plans that – if given the final go-ahead – will deliver real benefits for the people of Leith, north Edinburgh, and the city as a whole.”