Exeter Canal Bridges
A379 Exeter Canal Bridges Strengthening and Refurbishment Scheme
|Andy Matthews, Project Manager||
The bridges are on one of the main routes into Exeter and carry 36,000 vehicles a day. The swing bridge is used by traffic travelling out of Exeter and the adjacent bascule bridge is used by traffic entering the city.
The swing bridge was constructed in the 1930s and is an early example of a steel plate riveted girder bridge. Most of the mechanical and electrical equipment is original and needs replacing, and the bridge itself needs essential work to ensure that it can be operated to allow boats to pass up and down the Canal. In addition, strengthening of the bridge is required so that it can continue to carry heavy vehicles.
The lifting bascule bridge was constructed in the 1970s and its 30 year old mechanical equipment also needs a complete overhaul.
Both bridges are located adjacent to a SSSI (The Exe Estuary) and a RAMSAR. As a result both bridges had to be fully enclosed for the repainting operations to ensure all of the old paint did not contaminate the surrounding area.
The A379 is one of the busiest roads into Exeter. Every effort has been made to minimise traffic disruption, with the works being planned to avoid the need for traffic restrictions through the site during the day from 7am to 7pm until January. It was felt particularly important to avoid restrictions during the busy Christmas shopping period.
In the New Year single lane contraflow traffic management had to be used to allow the major strengthening works to be carried out on the Swing Bridge. Details of the traffic management arrangements were publicised well in advance in form of Press releases, traffic reports on the local radio and the use of the fixed variable message signs. Liaison between the Highways Operation Control Centre at County Hall and site took place frequently to ensure minimal disruption took place on the highway network during the contract.
Access for boats along the Canal also had to be restricted during the works. Small recreational craft were able to pass under the bridges at the weekends. The bridges were opened just before Christmas to allow boats access to the Canal Basin. The Swing bridge was opened by hand, teams of 2 taking turns to wind the bridge around using the original opening mechanism.
Certain elements of work to the bridges were carried out during the night to further reduce disruption to the highway user. Consultations took place with Exeter City council and local residents were informed of the proposed works by letter drops.
Swing Bridge Works
The swing bridge has been carrying traffic for over 70 years and the concrete deck was in need of replacing. In order to strengthen the bridge a thicker slab was required, this was constructed out of light weight concrete in order that the overall weight of the bridge was not increased significantly, this was reinforced with Stainless steel. This is the first time a bridge in Devon has been built using both of these materials. Over 1000 rivets were also replaced as part of these works.
The original electrical opening mechanism has been completed replaced together with new control equipment in the refurbished control room.
The County Council also took the opportunity to improve passage over the swing bridge for pedestrians and cyclists by providing a new footway attached to the side of the bridge.
Bascule Bridge Works
The Bascule Bridge (French for SeeSaw) was built in the 70’s to reduce congestion on the A379. The main works to this bridge involved replacement and refurbishment of the hydraulic operating mechanism.
A new power pack has been built and installed in the plant room. The main lift cylinders were refurbished and new locking mechanisms have been installed.
The total value of the works was £2.5 M