128. MAIN HIGHWAY. The main road to Glen Canyon Dam and Page, Ariz. is discussed in subsection 4(h).

No.

129. SERVICE ROADS. Specifications DC-4825 provided for the construction of approximately 2 miles of service road and access highway, excavation of approximately 9,000 feet of road tunnel and its approaches, and construction of the highway approach embankments for the Glen Canyon Bridge. The bridge is described in the report "Glen Canyon Bridge-Technical Record of Design and Construction." The powerplant service road and the right and left abutment service roads were built 30 feet wide shoulder to shoulder with a 4-inch crushed-rock base and a 24-foot-wide bituminous surface treatment. The powerplant service road tunnel was constructed on a maximum 8 percent grade with a 20-foot wall-to-wall roadway. The road has a 6-inch crushed-rock base and a bituminous surface treatment. Part of this service road was designed to be in open cut traversing a talus area between two tunnel sections. Owing to the unstable condition of the rock face in this area, it was decided to realine the road farther into the rock cliff and make it a continuous tunnel road. Adits 12 feet wide were constructed normal to the centerline of the tunnel on approximately 500-foot centers and extended from the tunnel to the face of the canyon wall. The left abutment service road was connected directly to the end of the dam. The right abutment service road was connected to the dam by a short steel girder bridge 30 feet wide designed for a H20-S16 loading in accordance with AASHO, 1957 edition. Short service roads were also constructed to the spillway intakes.

130. ACCESS ROADS. The access highway joining Glen Canyon damsite with U.S. Highway No. 89 was constructed in two reaches. Under specifications No. DC-4730 the first 4.5 miles of access highway, beginning at U.S. Highway No. 89, was constructed to the roadway subgrade which is 42 feet wide (fig. 242). At Echo Cliffs an unusually heavy cut approximately 280 feet deep was required. The original design at Echo Cliffs called for an 800-foot-long tunnel, but the open cut was finally selected as more desirable. The surfacing and guardrail for the entire access highway was built under specifications No. DC-4887.

The second reach of access highway, ending at the Glen Canyon bridge approach, was constructed under specifications No. DC-4756. The work consisted of constructing approximately 20 miles of roadway to a 42-foot-wide subgrade. A 140-foot reinforced concrete bridge was constructed across Waterholes Canyon. The bridge is a reinforced concrete rigid-frame structure

with inclined legs. The design was based on H20-S16 loading in accordance with "Standard Specifications for Highway Bridges," of the American Association of State Highway Officials, 1953 edition; and for H20-S16 loading plus a 75-ton trailer load at normal unit stresses and H20-S16 loading plus a 100-ton trailer load at 120 percent of normal unit stresses.

Specifications No. DC-4887 provided for the surfacing and guardrail for the entire access highway from U.S. Highway No. 89 to the Glen Canyon bridge, a distance of approximately 25 miles. A 6-inch crushed-rock base was placed on the subgrade prepared under the other specifications, and 4 inches of plant-mix bituminous surfacing was then added. The finished road surface width is 34 feet. Beam-type guardrail was erected where necessary. Plant-mix bituminous curbs and spillways were placed on the roadway where required. Through supplemental notice No. 1, specifications No. DC-4887 was revised to include the construction of Manson Mesa airstrip. The runway is 4,500 feet long and 500 feet wide shoulder to shoulder. The 150-foot surfaced landing strip consists of 3 inches of plant-mix bituminous surfacing placed on a 6-inch crushed-rock base. An airplane parking area and 50-foot taxiways were also constructed using the same surfacing section.

Specifications No. DC-4896 provided for the construction of access roads to the community of Page, Ariz. (fig. 243). The connecting road, community to dam, approximately 1.7 miles long, was constructed with a 30-foot width shoulder-to-shoulder and with 1-1/2 inches of plant-mix bituminous surfacing over a 6-inch crushed-rock base. The north community access road, approximately 0.5 mile long, was built using the same roadway section as the connecting road. Both roads had a stone-chip seal coat. The south community access road was also of similar roadway section, except the bituminous surfacing was not required. This road is approximately 1.1 miles in length.

Under specifications No. 400C-83 an existing road was reshaped, a new road and a parking area were constructed, and all were surface treated. This construction provided access from the Arizona-Utah State line to the vista point and parking area at the right abutment of the Glen Canyon damsite. Approximately 7 miles of 6-inch crushed-rock surfacing 20 feet wide was reshaped by scarifying, blading, and rolling. The 0.75 mile of new road, with a 24-foot roadway and 3-foot shoulders, and the 4,200-square-yard parking area have 6-inch crushed-rock bases. To the 7.75 miles of road and the parking area was applied a modified penetration treatment of RC-5 cutback asphalt.