Scope also included assessing the probable construction costs to repair and upgrade each tunnel to a 20-year life expectancy, as well as to accommodate “double-stack” rail cars.  Of the 34 short line railroad tunnels in Oregon, Shannon & Wilson evaluated 20 Central Oregon & Pacific Railroad (CORP) tunnels and four Portland & Western Railroad (P&W) tunnels using available data and visual reconnaissance.  

Our team found that about half of these tunnels needed significant rehabilitation to provide another 20 years of service; in addition, most of these tunnels required some degree of modification to accommodate double-stack rail cars. Twenty five percent of the total evaluated tunnel footage was supported with aging timber lining.  We also observed that all the tunnels could achieve double-stack clearance through a combination of track realignment, grinding of notches in the concrete portal barrels, removing obstructing timber or steel sets, and undercutting to lowering the tunnel bottom.  

As a direct response to the condition assessments, CORP (under new ownership) moved forward to improve clearance, lining, and drainage on several tunnels on the Siskiyou line. These clearance improvements and tunnel repairs allowed the railroad to reopen the line, significantly increasing capacity and improving service.