Edinburgh's Trams and HS2

The Telegraph reports that

Edinburgh's trams 'will be running by May'

We are also told that the original estimate of £375 million more than doubled at £776 million as did the planned time-scale of three years which became six. The original plans for the trams to run from Edinburgh Airport to Newhaven in the north of the city, were scaled back due to problems, and they will now only run to the City Centre.
So they've got less than originally proposed at twice the cost and twice the time-scale.

I would suggest that there are "lessons to be learnt" in respect of HS2. With far higher estimated costs and longer time-scales, I would argue that both are  likely to more than double before the line is finished, and that it will never get beyond Birmingham.