BAD things happen and the human impulse is to ask why.

But in modern Britain, and no doubt beyond, there is then a depressingly familiar train of events. The Edinburgh trams project is a particular case in point.

The bad things that happen follow grimly familiar tracks - projects were too costly, too late, too poor in their intended outcomes. And then come Public Inquiries, which themselves prove to be too costly, too late, to poor in their outcomes.

As a result, sometimes we even get the great joy of a second inquiry into the failures of the first one, such as the Saville Inquiry into Bloody Sunday, which itself was a follow up to the initial report, some insist whitewash, by Lord Widgery in the aftermath of the 1972 deaths in Derry.

Lord Saville then managed to conduct his own inquiry over a period of no fewer than 12 years, a £200 million absurdity which was entirely overtaken by history given that by the time of publication Sinn Fein's Martin McGuinness, who had been in the Bogside that day, and DUP leader Dr Ian Paisley, had become Deputy First Minister and First Minister of Northern Ireland, nicknamed the "chuckle brothers".

The Chilcot Inquiry into the Iraq War, started in 2009, ceased taking its evidence in 2011 but, it appears, may never actually publish anything, at least until all those involved in the original bad decision give their permission.

And then, closer to home we had the Fraser Inquiry into the design and building of the new Scottish Parliament, swifter in both its evidence gathering and conclusions but, dare we say it, telling us little more than most political journalists could have told you if asked - never start a project that's not designed yet. The military do this all the time, which is why we end up with aircraft carriers with no aircraft.

The Edinburgh trams project was a tragedy for the city. With no underground network, such as the Glasgow Subway, and the old suburban rail network turned over to walkers and cyclists, trams were seen as the mass transit solution to getting people into town from Leith at one end and the airport at the other.

Instead, it ran three years late and more than £200m over budget for a severely truncated line. We don't need anyone to tell us this happened. We need to know why it happened, so we can avoid similar public procurement disasters in future.

Lord Hardie is now presiding over another of these inquiries which seems likely to grow legs and arms. There is not doubt that individuals were inconvenienced and small businesses were ruined as this project failed to make its way down Leith Walk. His conclusions will no doubt fuel litigation by fellow layers.

But we should be concentrating on who made which contract decisions with whom and when, and whether these contracts were flawed. That is urgent business if the city is to get on with improving its infrastructure.

Instead, his lordship is now opening his already bloated inquiry up to personal grouse when we need public clarity. We would urge him to focus on public procurement, with swift recommendations paramount.