IF Edinburgh's trams project and Glasgow's ill-fated rail link development tell us anything, it is that politics, public money and infrastructure are a combustible mix.

It seems nothing is as likely to descend into squabbles, shambles and scandal like a transport project, or as liable to polarise public opinion.

Even as the capital's trams development nears its conclusion - they should be up and running next summer - there is still a keenly-felt scepticism among many Scots about whether the time, cost and inconvenience was really worth it for a track that will carry passengers from Edinburgh city centre to the airport - a route already covered pretty efficiently and cheaply by an existing bus service.

As for the Glasgow Airport Rail Link, its only legacy seems to be a continuing enmity between the Labour councils that lost out and the Scottish Government that scrapped it.

A fresh war of words erupted this week when it emerged - more than four years after the rail project was axed - that while it had cost taxpayers almost £2 million to buy the land in 2008, it was sold off between 2011 and 2013 for less than £360,000. A further £8.5m was paid out in compensation to businesses forced to relocate, and as at September 19 the Scottish Government had spent close to £30m on the cancelled rail link.

So it should really come as no surprise that the UK's High-Speed Rail Scheme, HS2 - what is claimed to be the most ambitious transport project in a generation - is quickly descending into a bitter tussle between rival political parties, environmentalists, train enthusiasts, the business world, and homeowners caught in its path.

Whether it is ever completed or not, journalists will probably still be picking over the fallout of incompetence, mismanagement and squandered funds 30 years from now. Because where there are transport projects, ballooning costs and waste almost inevitably follow. The question is simply whether, in the end, it is worth it.

So far, the estimated cost of completing phase one of HS2 - linking London to Birmingham by 2025 - has gone from £16 billion to £21bn plus. By the time the extension to Manchester and Leeds by 2033 is added in it is officially estimated to cost £42.6bn, but critics have put the price tag closer to £50bn and rising.

All this will cut the duration of a train ride from Glasgow to London by a not entirely exciting 53 minutes, to three hours 37 minutes. So, after £50bn and 20 years of investment, it will still take three times as long to travel between the two cities by train as by air.

Of course, the Scottish Government is arguing that the line should be extended north of the Border and haswon the backing of the Institute Of Civil Engineers, which on Monday said the "economic case" for HS2 was strongest when Scotland was included. Worryingly, a failure to do so would also leave Scots "disproportionately further from key UK markets" and at risk of losing out on inward investment, the institute said.

In effect, then, Scots taxpayers could be helping build a high-speed rail link that could leave us 53 minutes closer to London, but economically worse off.