Constructing the arches
Passers-by at the Strood end of the Old Bridge will see there has been good progress on the workshop walls.
As well as the first major sections of wall now being complete, we have also completed construction of the first arch.
The principles of building an arch are the same whether for a bridge or as part of any other structure. The photographs of the construction of this arch will therefore look familiar to readers of Learning about Bridges, the Trust’s free education book.
The first picture shows the formwork in place.
Next the voussoirs are added.
Finally, we have the completed arch. In the photograph it is still supported by the formwork, but once the mortar hardens, the formwork can be removed. This arch will be strong enough to support the weight of the cast iron bridge parapet above it.
To find out more about the role of the voussoirs, and how an arch bridge is always in compression, feel free to take a look at lesson plans seven and eight on our education website.