Bridges: When it Comes to the Crunch
How safe are bridges? Public confidence in bridge engineers sagged with the failure of four of the latest steel box girder constructions in 1970. No fewer than 60 British bridges had to be strengthened.
The history of bridge design is littered with wrecks caused by the failure of designs which went beyond the knowledge of their time.
Bridges are designed to engineering formulae which have been derived from previous work. The problem is that the biggest bridges have no comparable predecessors and the old rules don'always work. The only way out is to do research on models. But, as in the case of box girders, the research too often gets done after the collapses.
Narrator WILLIAM FRANKLYN
Editor BRUCE NORMAN
Producer MICHAEL ANDREWS ‡