US Bridges

Unadilla Road over Portage River

Fair

Livingston County, Michigan · Sec 35 Unadilla Twp · Structure no. 000000000005830

Built
1926
99 years old
Condition
Fair
inspected June 2024
Type
Tee Beam
Concrete
Length
31 ft
1 main span
Daily traffic
1,350
2013 count
Owner
County
County Highway Agency

About this bridge

Unadilla Road over Portage River is a concrete tee beam carrying Unadilla Road over Portage River in Livingston County, Michigan. It was built in 1926, so it is 99 years old, older than the Michigan average of 48.3 years.

The most recent inspection reported to the Federal Highway Administration rates it in fair condition with a lowest component rating of 5 out of 9. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

It carries about 1,350 vehicles a day, projected to reach 2,250 by 2012. The structure is 31 ft (9.4 m) long and 21 ft wide. If it were closed, the detour would be 3.1 mi (5 km).

Location

Open in Google Maps
CarriesUnadilla Road
CrossesPortage River
LocationSec 35 Unadilla Twp
RouteCounty Highway 4717
CountyLivingston County
StateMichigan
Coordinates42.43061, -84.05801
Functional classRural Major Collector

Condition and inspection

Fair

The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

ComponentRatingMeaning
Deck5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Last inspectionJune 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry2: Basically intolerable, requiring high priority of replacement
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating60.2 US tons
Inventory rating36 US tons

Structure

Structure typeTee Beam
MaterialConcrete
DeckConcrete, cast-in-place
Main spans1
Design loadHS 20 + Mod
Structure length31 ft (9.4 m)
Longest span30 ft (9.1 m)
Deck width21 ft (6.4 m)
Roadway width19 ft (5.8 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic1,350 (2013)
Projected traffic2,250 by 2012
Trucks0%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed3.1 mi (5 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCounty Highway Agency
Maintained byCounty Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was Unadilla Road over Portage River built?

It was built in 1926, making it 99 years old in 2025.

What condition is Unadilla Road over Portage River in?

The National Bridge Inventory rates it in fair condition. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound. The last reported inspection was in June 2024.

How much traffic does Unadilla Road over Portage River carry?

About 1,350 vehicles per day (2013 count).

How long is Unadilla Road over Portage River?

The structure is 31 ft (9.4 m) long with a longest span of 30 ft (9.1 m) and a deck 21 ft wide.

Who owns Unadilla Road over Portage River?

It is owned by the County Highway Agency.