Presentation on theme: "Dennis L. Edwards Tunnel"— Presentation transcript:
1 Dennis L. Edwards Tunnel Constructability ReviewFebruary 5, 2010East Portal looking west circa 2001Nathan K. Potter, PEProject ManagerOregon Department of TransportationRandy G. Hinderer, PESenior Project ManagerLOCHNEREast Portal looking west circa 1940
3 Dennis L. Edwards Tunnel Originally called the Sunset Tunnel, construction was completed by the Works Progress Administration (WPA) in 1940.The tunnel was renamed after Dennis Edwards, a member of the District 2A staff who was killed during inspection activities in January 1999 when part of the tunnel collapsed. Closure and detour duration was approximately 5 weeks.Technical DataUS26 (Sunset) (Highway No. 047)Mile point: 40.9Bridge NoPosted Speed: 55 MPHAverage Daily Traffic (ADT): 6,700Average Daily Truck Traffic (ADTT): 12% (804)
31 Alternative 1: Lining Only Replaces the tunnel liningReplaces / rehabilitates the tunnel PCC floor and drainage systemInstalls new lighting systemExisting portals and stone masonry will remain untouched.
32 Alternative 2: Floor Lowering Clearance achieved by removing the existing lining consisting of steel and timber sets, removing the rubble and gravel behind the existing liner, and replacing the liner with rock bolted shotcrete directly to the exposed siltstone bedrock.Roadway elevation will be lowered throughout the tunnel approximately 2.5 feet to achieve vertical clearance, transitioning back to existing grade approximately 700 feet on both tunnel approach sections.Existing portals and stone masonry will remain intact, however underpinning the portal masonry and associated concrete wall structure with new footings will be necessary.
33 Alternative 3: Portal Raising Clearance achieved by removing the existing lining consisting of steel and timber sets, removing the rubble and gravel behind the existing liner, and replacing the liner with rock bolted shotcrete directly to the exposed siltstone bedrock.Existing portals will be raised approximately 2.5 feet to achieve vertical clearance.RequireS specialized work for the historic portal stone masonry, which will be removed and replaced on a new portal wall structure at a higher elevation.
34 Constructability Review Agenda GOAL: What is the highway closure duration? EquipmentDimensionsLocationWhat equipment will be required to raise the portals, excavate, etc., will it fit in the tunnelMethodsContingency plans for unknownsRoadway undercuttingWhat protection / shoring methods will be required for the portals?Lowering the tunnel floor and roadway:Historic Stone Portal Removal and ReconstructionSpecialty work required to maintain material integrity during removal and reconstructionTimber Lining DemolitionShotcrete Lining DemolitionMaterialsConcreteMasonry materialsHistoric Stone Portal UnderpinningStagingRaising PortalsRe-LiningIs it feasible to lower the tunnel floor, construct temporary ties into existing roadway, and stage approach roadway construction with single lane closures?Is there any methodology to keep the highway partially open?DurationsExisting lining removalRoadway loweringRising portals: reconstruction verses liftingFull closure versus partials