Meeting in the middle

Yesterday's Guardian had a striking picture of the last segment being hoisted into place between the two halves of a new bridge across the Firth of Forth, with the thus completed central span of this cable stay bridge earning a place in the Guinness Book of Records.

As far as one can tell from the picture, the left hand span did indeed meet the right hand span, from where I associate to an M5 bridge over the River Bredon, north of Tewkesbury, where something went wrong and one side was a few centimetres adrift from the other. Presumably problem solved with a bit of screed.

Perhaps things are a bit easier now, with much fancier theodolites available to the supervising engineers, no doubt linked to big databases by satellite.

Newspaper pictures do not scan very sharp, so I turned to google, who could not find the picture at all. Maybe it was only available to Platinum Subscribers to the Guardian - of which I am not one. But it did turn up the picture above which does get across the idea that one needs to meet in the middle. And the concrete segments or cells from which the (unknown) bridge in question is made, do look much the same as those in the Guardian's picture.