US Bridges

109th Ave over Swan Creek

Good

Allegan County, Michigan · Approx 0.10 MI W of 48 ST · Structure no. 000000000000171

Built
1979
46 years old
Condition
Good
inspected September 2023
Type
Box Beam or Girders - Multiple
Prestressed Concrete
Length
36 ft
1 main span
Daily traffic
1,676
2016 count
Owner
County
County Highway Agency

About this bridge

109th Ave over Swan Creek is a prestressed concrete box beam or girders - multiple carrying 109th Ave over Swan Creek in Allegan County, Michigan. It was built in 1979, so it is 46 years old, younger than the Michigan average of 48.3 years.

The most recent inspection reported to the Federal Highway Administration rates it in good condition with a lowest component rating of 7 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

It carries about 1,676 vehicles a day, roughly 7% of them trucks, projected to reach 2,490 by 2036. The structure is 36 ft (11 m) long and 33 ft wide. If it were closed, the detour would be 3.7 mi (6 km).

Location

Open in Google Maps
Carries109th Ave
CrossesSwan Creek
LocationApprox 0.10 MI W of 48 ST
RouteCounty Highway 318
CountyAllegan County
StateMichigan
Coordinates42.48436, -86.01226
Functional classRural Major Collector

Condition and inspection

Good

All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

ComponentRatingMeaning
Deck8 Very GoodNo problems noted.
Superstructure7 GoodSome minor problems.
Substructure8 Very GoodNo problems noted.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionSeptember 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation7: Better than present minimum criteria
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment7: Better than present minimum criteria
Operating rating62.5 US tons
Inventory rating37.5 US tons

Structure

Structure typeBox Beam or Girders - Multiple
MaterialPrestressed Concrete
DeckConcrete, precast panels
Main spans1
Design loadHS 20 + Mod
Structure length36 ft (11 m)
Longest span36 ft (11 m)
Deck width33 ft (10.2 m)
Roadway width31 ft (9.6 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic1,676 (2016)
Projected traffic2,490 by 2036
Trucks7%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed3.7 mi (6 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 109th Ave over Swan Creek built?

It was built in 1979, making it 46 years old in 2025.

What condition is 109th Ave over Swan Creek in?

The National Bridge Inventory rates it in good condition. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted. The last reported inspection was in September 2023.

How much traffic does 109th Ave over Swan Creek carry?

About 1,676 vehicles per day (2016 count), of which roughly 7% are trucks.

How long is 109th Ave over Swan Creek?

The structure is 36 ft (11 m) long with a longest span of 36 ft (11 m) and a deck 33 ft wide.

Who owns 109th Ave over Swan Creek?

It is owned by the County Highway Agency.