The proposed project on Elochoman Valley Road would dovetail with a separate funding request to the Lower Columbia Fish Recovery Board for replacement of an undersized culvert at Clear Creek with a bridge. The planned bridge would utilize recycled concrete girders provided by the Port of Seattle.
The primary objective of this RAP project is to enhance safety. The ideal time for this work is in conjunction with design and construction of a new bridge. Once the alignment of the bridge is set, it will constrain both future vertical and horizontal alignment improvement options.
Elochoman Valley Road is a T3 truck route serving a large area of mainly private timberland holdings. The road dips down at the location of the existing culvert, introducing an un-necessary depth to the sag vertical curve and the associated issues with stopping distance at night. At the same location as the sag of the vertical, there is a series of short curves, some have radii as low as 230 feet, providing for a design speed below 30 miles per hour if they had an 8% super-elevation. Since the posted speed on this road is 50 mph, some improvements in these curve radii would be very desirable. Horizontal sight distance is very poor and can be improved through a combination of increasing the horizontal radius and excavating the cut bank on the side of the curve.
Additional width for a shoulder would also enhance safety through this segment. Where the existing alignment and grade is to be maintained by the project, weak areas of the base would be excavated out and strengthened. Resurfacing would provide for long pavement life, however a friction course is also recommended to help improve winter driving conditions.
The proposed project will enhance safety and will reduce maintenance expenditures on the improved segment.