HistoricBridges.org Menu: HistoricBridges.org Menu:

We Recommend These Resources:
Bach Steel - Experts at historic truss bridge restoration.

HistoricBridges.org: Bridge Browser

4 3/4 Mile Road Bridge

4 3/4 Mile Road Bridge

Primary Photographer(s): Nathan Holth

Bridge Documented: 2006 and November 13, 2021

View Photos
and Videos
View Maps
and Links

Key Facts

Facility Carried / Feature Intersected
4 3/4 Mile Road Over Pine River
Rural: Midland County, Michigan: United States
Construction Date and Builder / Engineer
1903 By Builder/Contractor: Tunnel City Bridge and Iron Works of Port Huron, Michigan

Technical Facts

Rehabilitation Date
Not Available or Not Applicable
Main Span Length
116 Feet (35.4 Meters)
Structure Length
120 Feet (36.6 Meters)
Roadway Width
15 Feet (4.57 Meters)
1 Main Span(s)
NBI Number

Historic Significance Rating (HSR)
View Information About HSR Ratings

Bridge Documentation

View Archived National Bridge Inventory Report - Has Additional Details and Evaluation

This bridge is the only known bridge in existence built by the Tunnel City Bridge and Iron Works of Port Huron, Michigan. It is thus extremely important as what may be the last physical remnant of a little-known Michigan bridge company. In case you are curious why the company named themselves "Tunnel City" consider Port Huron's history during the period the bridge company was in operation. In 1891s, the first full-size sub-aqueous tunnel in North America was completed, running from Port Huron, MI and Sarnia, ON to serve trains. In 1903 when the 4 3/4 Mile Road Bridge was built, this key international tunnel would have been a major source of fame for Port Huron. Engineers would have possibly nicknamed Port Huron "Tunnel City" back then. Click here to visit HAER's page for this historic tunnel.

This bridge has been moved for a number of years, as MDOT's website mentions, and it took some searching to find who moved the bridge and where it moved. It turns out that a nearby resident, Jim Hyatt, moved the bridge to a nearby private drive and restored it. HistoricBridges.org is appreciative that this beautiful piece of Port Huron heritage was saved from the dumpster, which is where the Midland County Road Commission was going to put it.

Constructed in 1903, this bridge is a classic example of a pin connected Pratt through truss. The bridge is composed of eight panels yielding a 120 foot span. V-lacing is present on the vertical members, and lattice is present on the portal bracing. The original railings on the bridge are also lattice.

The bridge has been altered, most notably with extensive plate steel welded to bottom chord elements. In addition, the flooring system was also replaced, but with a wooden deck. Although MDOT's website mentions that the deck of the bridge was originally concrete, wood was a common surface for pin connected through truss bridges.

The unusual, simple plaque on the bridge which is composed of a thin plate with punched holes spelling out the bridge builder and date might at first glance appear to be not original. However there are a couple other bridge companies who created plaques of this type. After careful consideration, HistoricBridges.org believes the plaque to be original.

HistoricBridges.org thanks Jim Hyatt for allowing a visit and and photo-documentation of this important bridge, and also for choosing to save this historic bridge from certain doom!

Information and Findings From Michigan Historic Bridge Inventory

Narrative Description

MDOT Historic Bridge Midland County 4 3/4 Mile Rd. / Pine River

Located over the Pine River about a mile east of Gordonville, this medium-span truss crosses the Pine River on the Gordonville Road. This pin-connected Pratt through truss, extending 120 feet, is supported by concrete abutments with angled wingwalls. The web members are built up from rolled steel sections from the Cambria mills of Pennsylvania. They are comprised as follows: upper chord and sloped end posts - two channels with cover and batten plates; lower chord - 2 looped rectangular eyebars; vertical - two channels with lacing (with two looped rectangular eyebars at the hip); and diagonal - two rectangular eyebars. The guardrails are lattice; The 12-foot-wide asphalt-covered concrete deck is supported by I-beam stringers and floor beams, which are field-bolted to the verticals. Other than the relatively recent installation of Armco guardrails and turnbuckled tension rods at the hip verticals, the bridge is unaltered. It is presently cloes to vehicular traffic.

From the 1870s through the 1910s, pinned Pratt through trusses were the bridge of choice for medium- and long-span application in Michigan. Patented in 1844 by Thomas and Caleb Pratt, the Pratt design was characterized by upper chords and vertical members acting in compression and lower chords and diagonals that functioned in tension. Its parallel chords and equal panel lengths resulted in standardized sizes for verticals, diagonals and chord members, making fabrication and assembly relatively easy.

"The Pratt truss is the type most commonly used in America for spans under two hundred and fifty feet in length," noted bridge engineer J.A.L. Waddell.

In the manufacturing industry, in which efficiency equated with profit, Pratt trusses received almost universal use. Virtually all of the major regional fabricators manufactured Pratt trusses and marketed them extensively to Michigan's counties and townships in the late 19th and early 20th centuries. As a result, more Pratt trusses were built in the state during the period than all other truss types combined.

Built in 1903 by the Tunnel City Bridge and Iron Works of Port Huron, the Pine River Bridge fits well within the milieu of Michigan bridge construction. This bridge is the only known surviving example of the work of the Tunnel City Bridge and Iron Works of Port Huron, Michigan, one of only a half dozen Michigan-based metal truss bridge companies to operated in the nineteenth and early twentieth centuries.

Moved to private property in the late 1990's.

This bridge is tagged with the following special condition(s): Unorganized Photos


Photo Galleries and Videos: 4 3/4 Mile Road Bridge

View Photo Gallery
2006 Bridge Photo-Documentation
A collection of overview and detail photos. This photo gallery contains a combination of Original Size photos and Mobile Optimized photos in a touch-friendly popup viewer. Alternatively, Browse Without Using Viewer
View Photo Gallery
Additional Unorganized Photos
Original / Full Size Photos
A supplemental collection of photos that are from additional visit(s) to the bridge and have not been organized or captioned. This gallery offers photos in the highest available resolution and file size in a touch-friendly popup viewer. Alternatively, Browse Without Using Viewer
View Photo Gallery
Additional Unorganized Photos
Mobile Optimized Photos
A supplemental collection of photos that are from additional visit(s) to the bridge and have not been organized or captioned. This gallery features data-friendly, fast-loading photos in a touch-friendly popup viewer. Alternatively, Browse Without Using Viewer


Maps and Links: 4 3/4 Mile Road Bridge

Coordinates (Latitude, Longitude):

View Bridge Location In:

Bridgehunter.com: View listed bridges within a half mile of this bridge.

Bridgehunter.com: View listed bridges within 10 miles of this bridge.

Google Maps

Google Streetview (If Available)

Bing Maps


Apple Maps (Via DuckDuckGo Search)

Apple Maps (Apple devices only)


HERE We Go Maps

ACME Mapper

Waze Map

Android: Open Location In Your Map or GPS App

Flickr Gallery (Find Nearby Photos)

Wikimedia Commons (Find Nearby Photos)

Directions Via Sygic For Android

Directions Via Sygic For iOS and Android Dolphin Browser

USGS National Map (United States Only)

Historical USGS Topo Maps (United States Only)

CalTopo Maps (United States Only)

Home Top


About - Contact

© Copyright 2003-2022, HistoricBridges.org. All Rights Reserved. Disclaimer: HistoricBridges.org is a volunteer group of private citizens. HistoricBridges.org is NOT a government agency, does not represent or work with any governmental agencies, nor is it in any way associated with any government agency or any non-profit organization. While we strive for accuracy in our factual content, HistoricBridges.org offers no guarantee of accuracy. Information is provided "as is" without warranty of any kind, either expressed or implied. Information could include technical inaccuracies or errors of omission. Opinions and commentary are the opinions of the respective HistoricBridges.org member who made them and do not necessarily represent the views of anyone else, including any outside photographers whose images may appear on the page in which the commentary appears. HistoricBridges.org does not bear any responsibility for any consequences resulting from the use of this or any other HistoricBridges.org information. Owners and users of bridges have the responsibility of correctly following all applicable laws, rules, and regulations, regardless of any HistoricBridges.org information.

Admin Login