Eagle River Timber Bridge

The Eagle River Timber Bridge is a wooden arch bridge carrying highway M-26 over the Eagle River in Eagle River, Michigan. It opened in 1990 as a replacement for the historic Lake Shore Drive Bridge that runs parallel to it.

Eagle River Timber Bridge
Coordinates47.4125°N 88.297°W / 47.4125; -88.297
CarriesAutomobiles
CrossesEagle River
LocaleEagle River, Michigan
Other name(s)Eagle River Bridge
ID number42142021000B050[1]
Preceded byLake Shore Drive Bridge
Characteristics
MaterialWood and steel
Total length152 feet (46 m)[2]
Width35 feet (11 m)[1]
Height50 feet (15 m)[2]
Longest span79 feet (24 m)[lower-alpha 1]
History
Construction start1988
Opened1990
Statistics
Daily traffic849 (in 2007)[1]
Location

History

Construction on the bridge began in 1988.[1][3] The quantity of wood used was equivalent to three or four average-size houses.[2] The bridge opened for highway M-26 traffic in 1990, at which point the neighboring Lake Shore Drive Bridge was restricted to pedestrian use.[4]

On August 26, 1992, the bridge was entered into the 1992 Timber Bridge Design and Construction Award Competition.[5] It was awarded first place in the "Long Span Vehicular Bridges" category.[6]

Design

The bridge is primarily constructed of wood joined together with steel connectors. It is supported by two adjacent arches: one spans 74 feet (23 m) and the other 79 feet (24 m). Each arch is constructed from two curved sections joined together by a crown hinge. The road deck is made of wood and covered by an asphalt road surface.[2]

All the timber members were structural glued laminated and pressure treated with preservative pentachlorophenol in oil. Any wooden portions which were cut or drilled also had an application of copper naphthenate. The steel pins in the hinges at the crown and abutments were chrome plated to reduce friction and prevent corrosion. All other steel was hot-dipped galvanized, given a tie-coat, and covered by epoxy and a top coat of brown urethane, a system designed to provide thirty years of protection.[2] The engineered timber members were manufactured in Peshtigo, Wisconsin by Sentinel Structures, Inc.

Bridge maintenance consists of reapplying preservative to all wooden members and any necessary tightening of bolts.[2]

Notes
  1. One arch spans 74 feet (23 m), the other spans 79 feet (24 m).[2]

References
  1. Conro, Steve (October 9, 2011). "Eagle River Bridge". BridgeHunter.com: Historic Bridges of the US. Retrieved January 1, 2012.
  2. Ness, Brian (June 1991). "The Eagle River Timber Bridge". Mates (54). Retrieved January 1, 2012.
  3. Staff (October 1, 2011). Highway Bridge Report (PDF) (Report). Michigan Department of Transportation. p. 61. Retrieved January 1, 2012.
  4. Staff. "Lake Shore Drive Bridge". State Historic Preservation Office. Michigan State Housing Development Authority. Archived from the original on June 12, 2012. Retrieved December 31, 2011.
  5. Bukoski, Glenn (November 1992). "1992 Member Bridge Award Competition". Mates (69). Retrieved January 1, 2012.
  6. "Timber Bridge Design Awards Announce" (PDF). Crossings. Timber Bridge Information Resource Center. February 1994. p. 2. Retrieved January 2, 2012.

Further reading
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