10 Mile Road Bridge

Key Facts

Bridge Name	Facility Carried / Feature Intersected	Location	Structure Type	Construction Date / Builder or Contractor
10 Mile Road Bridge	10 Mile Road Over Charlotte River	Rural: Chippewa County, Michigan	Metal Riveted Warren Pony Truss, Stationary	1914 By: Minneapolis Bridge Company of Minneapolis, Minnesota

Technical Facts

Structure Length	Roadway Width	Main Spans	Approach Spans
51.8 Feet (15.8 Meters)	16.4 Feet (5 Meters)	1	None

Thanks to Luke Gordon for visiting and photographing this bridge.

This bridge utilizes an uncommon lightweight truss design. When this bridge was built, it was a budget bridge, built as cheaply as possible, accounting for members that are more lightweight than most truss bridges of the period. Nevertheless, this bridge has managed to stand into the 21st Century. The bridge is closed to traffic and is not being maintained. Eventually this bridge may no longer be around. Sadly, the plaque that was once on this bridge has been stolen. Otherwise, this bridge retains good historic integrity, with a wooden deck and simple steel angle guardrails. The wooden posts that support the bridge at mid-span alter the historic integrity, but are a feature that could easily be corrected by removing them as part of a comprehensive restoration of this bridge.

MDOT's site incorrectly lists this bridge as being the Parker Road Bridge.

Information and Findings From MDOT

This small-scale pony truss carries Parker Road over the Charlotte River about 6 ½ miles east of Dafter. The bridge is a 50-foot, three-panel, rigid-connected Warren pony truss, with web members made up of back-to-back pairs of steel angles. I-beam floor beams are field-bolted to the verticals, and support the concrete deck. The webs are braced by steel-angle outriders bolted to the verticals. The truss is carried by concrete full-height abutments with angled wingwalls. The truss has more recently been braced by building a timber pile pier at mid-span. This is the only serious structural alteration it has undergone.

Before the standardization of truss bridge design by the state highway department, county and township road commissions in Michigan sometimes economized on bridge construction by substituting "two-angle" truss superstructures for the more traditional configurations. Instead of built-up box beams for the upper chord and end posts, these lighter structures used back-to-back angles, substantially decreasing the superstructural weight and, with cost predicated by the amount of steel in the bridge, reducing its cost.

Two-angle trusses were fabricated with both Pratt and Warren web configurations, invariably with rigid connections. The Parker Road Bridge in Chippewa County exemplifies this construction trend. A cast iron plate on its end post identifies its fabricator as the Minneapolis Bridge Company. Built in 1914, apparently for the Bruce Township Board, it is the only such two-angle truss in Michigan that has been definitively dated. As such it is distinguished as the best-documented representative of this relatively common pony truss subtype.

Visit MDOT's Historic Bridge Website