Condition Survey, Risk Assessment and Repair Designs for Five Tunnels on the John Wayne Pioneer Trail for the WSPRC Kittitas County, Washington
The Washington State Parks and Recreation Commission’s (WSPRC) John Wayne Pioneer Trail (JWPT) occupies the former Milwaukee Road railroad alignment which ran from Chicago to Seattle. The five tunnels that were constructed on the alignment in the early 1900’s have deteriorated leading WSPRC to award a contract to map defects and assess the risks they pose to the thousands of hikers, cyclists and equestrians that use the tunnels annually.
The assignment was divided into several tasks that included: Review of Historic Documentation; Historic Data Assimilation and Design Criteria; Design Repair Alternatives; Geotechnical Survey and Condition Assessments; and Tunnel Risk Assessments.
Evaluated by SubTerra
SubTerra’s Work Completed
Used to create 2D-Surface Mapping
As part of the project, SubTerra produced a comprehensive map and photo survey of Tunnels 46-49. Each tunnel was marked on10-foot stations and a map of the insidesurface of each segment was unwrappedonto a two-dimensional surface. Four crosssectionswere provided on each map wherethe depth of specific defects could be shown.Additionally, every square inch of the tunnels’lining was systematically photographed as acompliment to the maps and to establish a2008 baseline condition.For the Condition Assessment, SubTerraclosely inspected all areas of the tunnellinings, right up to the 23-foot-high tunnelcrown that was accessed with a rough terrainscissor lift. The lining was sounded with ahammer to identify delamination zones andassess the integrity of the 100-year-oldconcrete. Four cores were also drilled ineach tunnel from the lift as part of thecondition assessment.
Finally, a Risk Assessment matrix was created to quantify the risk to the public. Each of Tunnels 46-49, as well as portions of Tunnel 50, was divided into 40-foot sections that were evaluated based on the severity and extent of the defects for that section. Exponentially increasing values reflected the severity of the defects in individual scores. The total score for each section contributed to an overall ranking of low, moderate or high risk for the tunnel.
The next phase of our work will involve completing short-term and long-term repair designs and staged implementation of repairs consistent with available budget.
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