The Oregon State Parks and Recreation Commission has endorsed a plan to build a 570-foot tunnel and trail through Mitchell Point that resembles the tunnel that existed on the Historic Columbia River Highway before it was destroyed in 1966.  The Historic Columbia River Highway Advisory Committee had recommended the plan last month.  Oregon Department of Transportation officials say the plan is to balance open-air experiences and views with the appeal of a tunnel that nods to the past.  Adequate light within the tunnel and protection for potential falling rocks remain top challenges for engineers.  Design work for the Mitchell Point Crossing will continue through 2019 and includes acquiring a Columbia River Gorge National Scenic Area permit.  The tunnel plans currently include one arched window, and the design consultant will explore adding more windows to the tunnel, further mirroring the historic 1915 tunnel with its five arched windows.  The crossing will connect to western segments of the Historic Highway State Trail and east to Hood River and The Dalles.