Edmonton council approves extradosed bridge for LRT line

The city of Edmonton has approved the design of a bridge to carry a new LRT line over the North Saskatchewan River. The new bridge replaces the Cloverdale pedestrian bridge and is on the planned 27-kilometre Southeast to West LRT “Valley Line” whose first phase will run from the southeast of the city to downtown.

The selected bridge design is a three-span, single tower extradosed bridge, with an under-slung structure to carry pedestrians and cyclists.

An extradosed bridge was chosen from a set of eight possibilities, partly for technical and environmental reasons, but also after multiple consultations with the public. The three favourite options of the eight original possibilities were a three-span variable depth girder bridge, a three span single tower extradosed bridge, and a two-span single tower cable stayed bridge.

The public were divided into two camps: one group wanted a landmark bridge and favoured the cable stayed option, while in contrast, another group felt that the new bridge should be understated and not dominate the River Valley.

The selected extradosed design is seen as a balance between the dramatic impact of a “signature” cable stayed bridge but with more of the economical advantages of the “basic” span girder bridge. The extradosed bridge has a single set of pylons 20-25 metres high from which are strung cables that support the bridge deck.

A consortium of engineering companies known as connectED Transit Partnership (CTP) did the preliminary designs for the bridge and new LRT line . AECOM Canada leads the consortium and is in partnership with Hatch Mott MacDonald, Dialog, ISL and other companies. They are now charged with completing the preliminary engineering and specifications for awarding the project to a P3 contractor, who will ultimately be responsible for designing, constructing, operating and maintaining the new LRT line.

Meanwhile, about 2 kilometres northeast along the river another new bridge is taking shape. The new Walterdale Bridge at 105 Street will replace the 100-year old existing two-lane bridge with one carrying three lanes of traffic.