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and the lowest volume on any of the roads intersecting was at least 500 vehicles in the same hour.

Bridges

All bridges shall be of steel, reinforced concrete, or masonry construction, and designed for H20-S16 design loading. Bridges include all structures of a length between abutments greater than 20 feet.

Clear height shall be at least 14 feet over the entire width of traffic lanes and at least 12½ feet over the effective shoulder width.

The four-lane undivided pavement on this bypass of U S Route 101 in California was an attempt to cope with mounting traffic volume, The present 20,000 vehicles a day are far beyond the road’s practical capacity, and lack of access control prevents free-flowing movement. About 1,350 miles of the interstate system now surfaced with three or more lanes undivided should be rebuilt as multilane divided highways.

Clear width of bridges of a length of 80 feet or less between abutments shall be equal to the full width of the approach roadway including shoulders.

On bridges of a length greater than 80 feet between abutments, the width between the edge of the pavement and face of curb shall be at least 2 feet and preferably 3 feet. The face of the rail shall be in all