At an approximate contract value of $570,000, Oldcastle Precast - Central Pre-Mix Prestress manufactured and delivered the prestressed concrete Super Girders: (5) five Super Girders at 157’-8” long; (5) five Super Girders at 154’-8” long and (5) five Super Girders at 170’-2” long. Each Super Girder was 6’-10 5/8” deep x 4’-1” wide. The Super Girders were manufactured at Oldcastle Precast's Central Pre-Mix Prestress facility simultaneously as bridge work was completed. The installation of the Super Girders took only 15 days which contributed to the project being completed ahead of schedule.
Precast Prestressed Concrete Selected as the Preferred Structure Type
Previous successful experiences with prestressed concrete Super Girders led to their selection as the best solution for this bridge. At the forefront for selection of structure type was constructing a durable, aesthetically pleasing bridge which would be economical to build and require minimal investment in maintenance over a design life of 75 years. The new bridge is 491 feet in length and 45 feet wide which provides for (2) - 12 foot lanes, (2) - 4 foot shoulders and a 10 foot wide barrier protected shared use path. A framing configuration of three spans, made possible by use of precast Super Girders designed for live load continuity, was selected as the preferred structure type. This relatively new generation of prestressed Super Girders provided a perfect fit for the objectives of this project. The crossing could be accomplished with three spans without the false-work required for a cast in place or spliced girder solution. The new bridge design also incorporates some architectural elements that reflect the original design from 1939.
Oldcastle Precast - Central Pre-Mix Prestress Engineering Challenge
During the public process it was learned that an exposed rock formation on the river bottom beneath the bridge was the site of a nationally recognized hydraulic feature used by kayakers in the river. This new information led to a redesign which shifted the pier nearest the site approximately10 feet into span two and resulted in the lengthening of span three to just over 170 feet. State DOT design standards made this an engineering challenge as they required 100 % of both the HL-93 load and the pedestrian pathway load to be applied concurrently. The robustness and efficiency of the Super Girder shape combined with the availability of high strength concrete made meeting this challenge possible. The flexibility afforded by prestressed concrete allowed the design team to be responsive to the needs of the public in a way not routinely thought of in bridge construction and has resulted in a project which diverse user groups embrace and are supportive of.
The general contractor for the project was Harcon Incorporated of Spokane, WA. Construction began at the end of May 2010 and completed November 2011. The design was done by the Spokane County Engineering Department with assistance from Sargent Engineering of Olympia, WA.
About Oldcastle Precast, Inc.:
Oldcastle Precast, Inc. is the leading manufacturer of precast and polymer concrete products in the U.S. Providing engineered product solutions nationwide to a number of market sectors including:
Building Structures – Communications – Government/Military
Power & Energy - Security - Transportation – Water
Construction Services – Engineering Support – LEED/Green Consulting