Glan Hafren Bridge – Canal and River Trust

Constructing Excellence

When the Montgomeryshire Canal was extended to Newtown in the early 1800s, Glan Hafren Bridge was built to carry the entrance driveway to Glan Hafren Hall over the new waterway. Under the Act of Parliament for the construction of the canal, property owners could “construct for themselves bridges of a more elaborate nature than would normally be erected…”. Hence, Glan Hafren Bridge is a statement structure of architectural merit, now Grade II listed. The main beams are formed from the Victorian engineers favoured new material: cast iron.
Over 200 years, the bridge has inevitably deteriorated to some extent. But, the most significant risk to its fabric is the huge increase in the weight of typical vehicles: originally horse and carts, now potentially vehicles with 11 tonne axles! When assessed by engineers, the theoretical load capacity was practically zero. As owners of the bridge, the Canal & River Trust were obliged to intervene with a strengthening scheme.
Key challenges faced in the design and construction were:
1. Respecting a unique heritage structure.
2. Maintaining access to the properties including a business and farm land for which the bridge is sole access.
3. Maintaining traffic flows on the A483 trunk road which the bridge is sited directly alongside.
4. Preventing any adverse environmental impact: the canal under the bridge is part of both a SSSI and Special Area of Conservation, due to the presence of European Protected Species “Luronium Natans” (commonly known as Floating Water Plantain).