\r\nThe project is included in the Glasgow and Clyde Valley City Deal, which will devolve \u00a31bn in British Scottish government funding to the city and surrounding region for investment in transport and regeneration. The City Deal will also enable local authorities to borrow up to \u00a3130m for capital investment.\r\nTram-trains would use existing heavy rail infrastructure between Glasgow Central and Paisley Gilmour Street before joining a new light rail alignment, which would terminate outside the airport terminal building. The estimated cost of the project is \u00a3144.3m including rolling stock, inflation, contingencies, and land acquisition. Construction could start in 2021, which would enable the line to open in 2021.\r\nThe city council says studies have shown that a tram-train link would be the best performing option, although a \u00a3102m personal rapid transit link between the airport and Paisley is still being considered as an alternative. The two proposals are included in a strategic business case developed jointly by Glasgow City Council and Renfrewshire County Council, which will be put to local councils for approval next month.\r\nPlans for a heavy rail link to Glasgow Airport were scrapped in September 2009 amid concerns over public spending. The latest study puts the cost of a heavy rail connection at \u00a3317m, considerably more than the cost of the abandoned scheme.