US Bridges

Hill Island Road over Flower Bay Lake Huron

Good

Mackinac County, Michigan · 0.25 MI S of M-134 · Structure no. 000000000005979

Built
2018
7 years old
Condition
Good
inspected November 2024
Type
Culvert
Concrete
Length
48 ft
1 main span
Daily traffic
606
2016 count
Owner
County
County Highway Agency

About this bridge

Hill Island Road over Flower Bay Lake Huron is a concrete culvert carrying Hill Island Road over Flower Bay Lake Huron in Mackinac County, Michigan. It was built in 2018, so it is 7 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 8 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

It carries about 606 vehicles a day, roughly 5% of them trucks, projected to reach 697 by 2036. The structure is 48 ft (14.6 m) long. If it were closed, the detour would be 124.3 mi (200 km).

Location

Open in Google Maps
CarriesHill Island Road
CrossesFlower Bay Lake Huron
Location0.25 MI S of M-134
RouteCounty Highway 0
CountyMackinac County
StateMichigan
Coordinates45.99539, -84.3312
Functional classRural Minor Collector

Condition and inspection

Good

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

ComponentRatingMeaning
Channel and channel protection8 Very GoodNo problems noted.
Culvert8 Very GoodNo problems noted.
Last inspectionNovember 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation8: Equal to present desirable criteria
Waterway adequacy9: Superior to present desirable criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating59.6 US tons
Inventory rating46.4 US tons

Structure

Structure typeCulvert
MaterialConcrete
DeckNot applicable
Main spans1
Design loadGreater than HL 93
Structure length48 ft (14.6 m)
Longest span46 ft (14 m)
Deck width0 ft (0 m)
Roadway width0 ft (0 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic606 (2016)
Projected traffic697 by 2036
Trucks5%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed124.3 mi (200 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 proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost$944,000
NavigationNo navigation control on waterway

Frequently asked questions

When was Hill Island Road over Flower Bay Lake Huron built?

It was built in 2018, making it 7 years old in 2025.

What condition is Hill Island Road over Flower Bay Lake Huron 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 November 2024.

How much traffic does Hill Island Road over Flower Bay Lake Huron carry?

About 606 vehicles per day (2016 count), of which roughly 5% are trucks.

How long is Hill Island Road over Flower Bay Lake Huron?

The structure is 48 ft (14.6 m) long with a longest span of 46 ft (14 m).

Who owns Hill Island Road over Flower Bay Lake Huron?

It is owned by the County Highway Agency.