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Trunk Line 13 - Manistee River Bridge

Photo 

Photo taken from Michigan Roads and Construction - Volume 20 - 1923

Enlarge

BH Photo #509192

Facts 

Overview
Lost Pratt through truss bridge over Manistee River on Michigan State Trunk Line 13
Location
Wexford County, Michigan
Status
Replaced by a new bridge
History
Built 1893; replaced 1923
Builder
- Toledo Bridge Co. of Toledo, Ohio [also known as Smith Bridge Co.]
Design
Pratt through truss
Dimensions
Total length: 100.0 ft.
Approximate latitude, longitude
+44.48933, -85.41656   (decimal degrees)
44°29'22" N, 85°24'60" W   (degrees°minutes'seconds")
Approximate UTM coordinates
16/625903/4927443 (zone/easting/northing)
Land survey
Liberty T. 10 N., R. 9 W., Sec. 8
Inventory number
BH 94568 (Bridgehunter.com ID)

Update Log 

  • October 4, 2021: Updated by Mike Kerkau: Builder, build and replacement years, location detail
  • October 4, 2021: Added by Dave King

Related Bridges 

Sources 

Comments 

Trunk Line 13 - Manistee River Bridge
Posted October 5, 2021, by Nathan Holth (webmaster [at] historicbridges [dot] org)

Yes I think here you are seeing the evolution of increased traffic/weight requirements that occurred with all bridges urban and rural between these years, combined with the increased capacity requirements of a state trunkline.

US 131 - Manistee River Bridge
Posted October 5, 2021, by Mike Kerkau (mjkerkau [at] gmail [dot] com)

In other words, they're (typically) not intended for heavy traffic - but then (to use this example) once the road became a state trunkline, that brought on the traffic, and therefore prompted the replacement.

Trunk Line 13 - Manistee River Bridge
Posted October 5, 2021, by Nathan Holth (webmaster [at] historicbridges [dot] org)

Mike,

The reason for this change is the "transitional" length of the span. A 100 foot bridge in 1893, composed of the lightweight pin connected members in use at the time, typically would be built as a short through truss to provide the needed depth and stabilize the trusses. The replacement bridge, an MSHD standard pony, was designed with much heavier members and chords. These heavy duty members and chords would not need to be as deep, nor would they need to be stabilized as much. So for a moderate 100 foot span, the conversion from through truss to pony truss was possible. Some states like Indiana designed ponies as long as 140 feet however in the 19th century in contrast ponies are usually 80 feet and shorter (with some exceptions).

US 131 - Manistee River Bridge
Posted October 4, 2021, by Mike Kerkau (mjkerkau [at] gmail [dot] com)

I filled in additional details from the Roads and Construction listing (which I opted to link here, set on the relevant page) - actually, I got curious because it struck me as odd that a pony truss (even one of some size like a Parker) would replace a through.

I didn't really find an answer as to why the replacement was a pony, though I did find why they chose to replace this bridge when they did. Among other things...

I will also mention that this, technically, wouldn't have been "U.S. 131" until four years after replacement, in 1927. Actually, the state Trunk Line system was still relatively new when this was replaced (it was implemented halfway through 1919), but nevertheless this was T.L. 13 at that time.