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.

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.