||Remnants of masonry guard walls east of the Mosier Twin Tunnels. These walls were restored and adjacent sections recreated as part of ODOT's effort to rehabilitate the Hood River to Mosier section of the HCRH for pedestrian and bicycle use. (Photo by Jeanette B. Kloos, 1987)
In 1981 the National Park Service's Heritage Conservation and Research Service undertook a comprehensive study of the Historic Columbia River Highway (HCRH). Public agencies, private foundations, and others sponsored the project. A field team of architects, landscape architects, and historians investigated the entire route, including both drivable and abandoned segments to determine the extent of deterioration on the roadway, masonry, and related designed landscape features along the Highway. The reconnaissance project resulted in a comprehensive Historic American Engineering Record inventory of the road and established a benchmark for existing conditions.
The team issued several reports on the HCRH, including a Guide for Maintenance, and Options for Conservation and Reuse. They noted that the HCRH and associated features ranged from good to poor condition. In a few locations, the roadway had sunken several feet because hillsides experienced settling until they reached their slopes of repose. Layers of asphalt built-up from years of road resurfacing projects only accelerated subsidences. Overlays of asphalt also raised road surfaces in other areas to the point where concrete gutters were a foot or more below the edge of pavement, creating dangerous conditions for errant vehicles. In other instances, overlays had raised bridge deck pavements to curb levels, adversely affecting drainage and adding unnecessary dead loads to the structures.
Nearly every section of stonework has experienced deterioration. In some areas mortar was loose, had turned to powder, or was missing. Throughout the Highway, guard walls had missing stones or end posts, or were simply out of alignment. Likewise, exposed steel reinforcing in railing caps had rusted and damaged the concrete.
|Deteriorated railing spindles and cap on the Toothrock Viaduct. ODOT recast the spindles as part of the Tanner Creek to Eagle Creek project on the HCRH Trail. (Photo courtesy Robert Hadlow, Ph.D.)|
In some areas, concrete caps had slipped off of guard walls because of decayed reinforcing or because of crumbling masonry. On bridges, exposed reinforcing steel caused spalling on concrete railing balusters and decorative arched railing panels. In several locations, vehicles had also taken their toll on masonry walls, concrete railings, and guard rocks. Fortunately, only two bridges on the entire route have overhead bracing members and damage from tall vehicles has been limited to these structures.
Prior to the HCRH's construction, much of the timber throughout the Columbia River Gorge had been logged, followed by low-level vegetation and new tree growth. In the six decades since the road opened, trees have grown to obscure many of the view and vista vantage points that Samuel Lancaster and others sought out to include on the Highway's alignment.
The Oregon State Highway Department began abandoning segments of the Highway in the late 1930s upon completion of the new water-level route from Bonneville Dam to Cascade Locks. This work also segmented the original alignment, making it unusable even as a pedestrian trail. By the 1950s, much of the original alignment from Cascade Locks to Hood River had been sacrificed for the new water-level route. The HCRH from Hood River to Mosier, including the Mosier Twin Tunnels, was also abandoned. The Tunnels, located in a rockfall zone, were filled with rubble and allowed to "melt" into the rugged landscape. Throughout abandoned segments, walls fell over and perennial weeds grew through the pavement.