A 234′ Big R Pedestrian Bridge is maintaining a low profile these days under the new TRIMET Light Rail Bridge in Milwaukie, Oregon. Our sleek, Modified Bowstring Truss design recently side-slipped into place, all in one piece from a specially-made, temporary work platform over the Willamette River. Talk about an exact fit!
In fact, with it’s long-lasting Fiber Reinforced Polymer (FRP) composite decking and Weathering Steel finish, it will undoubtedly still be hanging in there for many decades to come — as it will also be maintaining a low profile on the maintenance roster.
Using lightweight FRP decking panels was key
Due to the side-slip installation method and the load requirements of the LRT bridge, using lightweight FRP composite decking panels was key in keeping the weight down, while offering a full suite of compelling advantages:
- Light weight: As little as 25% of the weight of concrete and 50% of wood.
- Corrosion resistant: Important in cold climates and coastal areas.
- High strength: Composite decking provides high strength with very high safety factors.
- Quick installation time: No formwork, curing times and possible weather delays.
- Lower life cycle costs: Long-lasting, zero-maintenance material adds up to significant savings over the 75-100 year life of the bridge.
Temporary work platform
Lightweight FRP Decking
The benefits of Naturally Weathering Steel
Weathering Steel contains elements that allow it to form a protective coating or patina when properly exposed to the atmosphere. This offers several benefits:
- Reduced toxic emissions: No oil-based coating is used, which reduces emissions of volatile organic compounds.
- No contaminated blast debris in habitats: Because the steel is not painted, no periodic maintenance blasting is required.
- Cost savings of 10% or more initially and even more over the life of the structure: No painting and steel’s durability mean reduced costs.
- Long life and high performance: Weathering Steel has been used on bridges for many decades and performs well in most environments.
Big R Bridge is proud to have been selected to participate in this portion of the large-scale TRIMET Light Rail Design/Build expansion project, known as the PMLR Transit project – West Segment.