New for Old

This is a third bit of local history, to go with my last two days' blips.
For several hundred years there was a stone bridge here, joining the districts of Llandaff and Llandaff North in the west of Cardiff..
The River Taff, which looks so peaceful in this shot, became a raging torrent at Christmas 1979 after 6 inches of rain fell on South Wales in 48 hours.
Around midnight on Boxing Day my wife, children and I stood beside a policeman as close to the river as it was safe to get. We could hear the stones of the bridge cracking as water smashed into it, and watched as gas engineers frantically used a pneumatic drill to locate a gas main buried in the bridge roadway.
The next day, large parts of Cardiff were flooded. The old bridge still stood but was condemned as unsafe, so that long road diversions became the order of the day.
Then the army stepped in. They constructed a self-supporting steel decking about a foot above the roadway of the stone bridge, which took all the weight of traffic so that road diversions were no longer necessary. Ramps at each end took care of the extra foot in height.
This worked very well for a couple of years whilst a new bridge, with its approach roads, was built.
After the new bridge opened, the army removed their construction and the old stone bridge was demolished.
In this shot, the remains of the old bridge on both banks of the Taff can be seen on the left, with the steel parapet of the new bridge on the right.