When is a bridge, not a bridge?

When is a bridge not a bridge? -When it is two. The left lane of this road is in fact part of an older viaduct,while the right part of the carriageway is an extension. Both parts of the bridge have a significant interest -historically. The girder structure to the right is in fact a cradle and it is the structure I eluded to in a previous blip.
Doctor's Bridge or Machine Bridge at Pontypridd is a three-arched stone viaduct over the River Taff, extensively remodelled with later accretions and carried one carriageway of a road, which formerly carried Dr. Richard Griffiths' Tramroad connecting collieries in the Rhondda Valley, via the Doctor's Canal , with the Glamorganshire Canal . A weighing machine for coal trams was installed nearby hence the local name given to the bridge.Although it never carried locomotives it did carry track that conveyed the coal drams.I believe it is listed as the oldest railway bridge/viaduct in the country.
As mentioned earlier it was remodeled and widened to take the road. This widening used a concrete structure attached to it's southern side. It is based on one of several reinforced concrete bridges in S Wales built on the system developed by the well known French engineer Francois Hennebique, who lived in S Wales for part of his life and was for a time the French consul for the area. I know that reinforced concrete bridges are an eyesore, but when the extension was built it was revolutionary! The steel structure found attached to the road surface was to strengthen the bridge so it could cope with modern traffic. It is ironic that it was the newer part of the bridge that could'nt cope. In the end the cradle was not enough to strengthen the roadway and another bridge was built right next to it. At this point the river is crossed by three bridges, or should that be four!
And for those out there, that are interested in the weather;-the wind was blowing from the south-west and the rain was coming straight down.