US Bridges

County RD 478 over Greenwood Reservoir

Poor

Marquette County, Michigan · 4.0 Miles South of US41 · Structure no. 000000000006544

Built
1972
53 years old
Condition
Poor
inspected October 2024
Type
Culvert
Steel
Length
30 ft
1 main span
Daily traffic
350
1996 count
Owner
County
County Highway Agency

About this bridge

County RD 478 over Greenwood Reservoir is a steel culvert carrying County RD 478 over Greenwood Reservoir in Marquette County, Michigan. It was built in 1972, so it is 53 years old, older than the Michigan average of 48.3 years.

The most recent inspection reported to the Federal Highway Administration rates it in poor condition with a lowest component rating of 3 out of 9. The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions.

It carries about 350 vehicles a day, projected to reach 450 by 2020. The structure is 30 ft (9.1 m) long. If it were closed, the detour would be 14.9 mi (24 km).

Location

Open in Google Maps
CarriesCounty RD 478
CrossesGreenwood Reservoir
Location4.0 Miles South of US41
RouteCounty Highway 5260
CountyMarquette County
StateMichigan
Coordinates46.44393, -87.81379
Functional classRural Major Collector

Condition and inspection

Poor

The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions.

ComponentRatingMeaning
Channel and channel protection7 GoodSome minor problems.
Culvert3 SeriousLoss of section, deterioration, spalling or scour have seriously affected primary structural components.
Last inspectionOctober 2024
Inspection intervalevery 12 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation3: Basically intolerable, requiring high priority of corrective action
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating32.8 US tons
Inventory rating19.6 US tons

Structure

Structure typeCulvert
MaterialSteel
DeckNot applicable
Main spans1
Design loadHS 20 + Mod
Structure length30 ft (9.1 m)
Longest span30 ft (9.1 m)
Deck width0 ft (0 m)
Roadway width0 ft (0 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic350 (1996)
Projected traffic450 by 2020
Trucks—
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed14.9 mi (24 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 County RD 478 over Greenwood Reservoir built?

It was built in 1972, making it 53 years old in 2025.

What condition is County RD 478 over Greenwood Reservoir in?

The National Bridge Inventory rates it in poor condition. The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions. The last reported inspection was in October 2024.

How much traffic does County RD 478 over Greenwood Reservoir carry?

About 350 vehicles per day (1996 count).

How long is County RD 478 over Greenwood Reservoir?

The structure is 30 ft (9.1 m) long with a longest span of 30 ft (9.1 m).

Who owns County RD 478 over Greenwood Reservoir?

It is owned by the County Highway Agency.