The Kincardine Bridge is a single carriageway swing bridge linking Stirlingshire with Fife and Clackmannanshire in central Scotland. When, opened in 1936, it was the lowest road crossing of the Forth, a fact which led to it becoming a Primary Destination. It has recently been joined by the Clackmannanshire Bridge a little upstream which helps share the ever growing load.
The 'entrance' to the bridge
Back in 1936 the Forth was still a busy shipping lane, so any bridge that was constructed had to be able to allow ships to pass. There are a range of ways that this could be achieved, but to cross the Forth the engineers (Gibb and partners of London) decided to construct a bridge with a swing section, although in this case the swing provided two clear shipping channels. It was constructed by the Cleveland Bridge Company of Middlesborough.
Stretching out from either bank are fairly ordinary concrete decks supported by paired legs. There are 7 spans on either side of the central swing section, which is supported by more substantial piers, with a large pontoon around the central pier to support the deck when it has swung open. The swing section is a substantial truss unit, cantilevered out either side of the central pier.
Obviously if the bridge is able to swing open, then there needs to be a control to stop the traffic. These days, level-crossing style gates or car park style barriers might be expected, but for the Kincardine Bridge the designers decided to go one better, and installed drop down beams in the entrance portals on the central section. They were, of course backed up with lights, but it still seems a little more substantial than is necessary!
The bridge last swung in 1988, with large shipping further up the forth having ceased. The bridge was permanently sealed shut the following year.
When first opened, the Kincardine Bridge seems to have taken the number of A977, which ran from Kinross into Falkirk. Later it was renumbered as the out-of-zone A876 between Falkirk and Kincardine. Then, when the M876 was opened, the western end of the A876 became the equally out-of-zone, and rather pathetic A88. Finally, with the opening of the Clackmannanshire Bridge the A876 was re-routed across the new bridge, and the Kincardine Bridge gained the A985 number which links it to the Forth Road Bridge.