Holbrook Bridge, Spanning Little Colorado River at AZ 77, Holbrook

Source document Quoted word for word from HAER ARIZ,9-HOLB.V,1-. Not written, edited or summarised by this site.

State Highway 77, spanning the LiUle Colorado River south of Holbrook; milepost of Section 6, Township 17 North, Range 21 East; Holbrook, Arizona USGS Quadrangle (15 minute series; Navajo County, Arizona UTM: Construction Date: February-September Engineer: Arizona Highway Department Contractor: Levy Construction Company, Denver Colorado

Source document Quoted word for word from HAER ARIZ,9-HOLB.V,1-. Not written, edited or summarised by this site.

Two-lane vehicular bridge (to be demolished in Description: superstructure: steel 10-panel rigid-connected Warren pony truss with verticals at alternate panels substructure : concrete abutments, wingwalls and piers floor/decking : concrete deck with steel stringers other features: upper chord/endpost: 2 channels with cover plate and lacing; lower chord: 2 channels with batten plates; vertical/diagonal: 4 angles with continuous plate; floor beam: I beam, field bolted to vertical; lateral bra- cing: 1 angle; pierced concrete guardrails; pin-connected rocker bearings; pedestrian sidewalks cantilevered outside of truss web on both sides.

Source document Quoted word for word from HAER ARIZ,9-HOLB.V,1-. Not written, edited or summarised by this site.

In the El Paso Bridge and Iron Company erected a two- span steel truss to replace the existing timber structure over the Little Colorado River at Holbrook. The bridge stood until the Lyman Dam broke upstream on April 14, criti- cally damaging its abutments. Although repairable in ten years later the Holbrook Bridge was deemed no longer suitable to carry traffic when Arizona Highway Department engineers began to survey a portion of the Holbrook - St. Johns Highway (U.S. Highway 70) in November By July the AHD bridge department had designed this four-span Hoi brook Bridge HAER No. AZ-9 page 2 pony truss with sidewalks cantilevered from the webs. The bridge was substantial, consuming over pounds of structural steel and 789 cubic yards of concrete. The agency waited over a year for the U.S.

Bureau of Public Roads to approve the design before letting bids for construction of the Holbrook Bridge. On December 12, the agency con- tracted with the Levy Construction Company of Denver under Federal Aid Project for Levy's crew commenced work in February and by April had poured piers 4 and 5. The Holbrook Bridge was completed on September It has since functioned unaltered and is now scheduled for replacement. As a major river crossing in the county seat, the Holbrook Bridge and its predecessors formed a regionally important transportational link in northeast Arizona. The bridge is technologically significant as one of the few multiple-span vehicular trusses remaining in a state in which steel was often eschewed in favor of concrete for bridge spans.

Such steel structures were never common in Arizona, and through attrition, only four such multi-span pony trusses remain in use: the Holbrook and St. Joseph bridges over the Little Colorado River in Navajo County, and the Charleston and Hereford bridges over the San Pedro River in Cochise County. A representative example of one of the most common vehicular truss configurations in America - the riveted Warren truss - the Holbrook Bridge is a noteworthy early structure. Report Assembler: Clayton B. Fraser Principal, Fraserdesign Cleveland Avenue Love!and Colorado October