US Bridges

Backbone State Pk over Br Maquoketa River

Fair

Delaware County, Iowa · In Backbone State Park · Structure no. 000000000699055

Built
1976
49 years old
Condition
Fair
inspected May 2024
Type
Slab
Concrete Continuous
Length
139 ft
4 main spans
Daily traffic
—
2022 count
Owner
State
State Park, Forest, or Reservation Agency

About this bridge

Backbone State Pk over Br Maquoketa River is a concrete continuous slab carrying Backbone State Pk over Br Maquoketa River in Delaware County, Iowa. It was built in 1976, so it is 49 years old, older than the Iowa average of 45.5 years.

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

No traffic count is recorded. The structure is 139 ft (42.4 m) long and 32 ft wide. If it were closed, the detour would be 123.7 mi (199 km).

CarriesBackbone State Pk
CrossesBr Maquoketa River
LocationIn Backbone State Park
RouteState Lands Road 0
StateIowa
Coordinates42.59979, -91.53827
Functional classRural Local

Condition and inspection

Fair

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

ComponentRatingMeaning
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure7 GoodSome minor problems.
Channel and channel protection7 GoodSome minor problems.
Last inspectionMay 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation6: Equal to present minimum criteria
Deck geometry7: Better than present minimum criteria
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment4: Meets minimum tolerable limits to be left in place as is
Operating rating61.5 US tons
Inventory rating36.9 US tons

Structure

Structure typeSlab
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans4
Design loadH 20
Structure length139 ft (42.4 m)
Longest span39 ft (11.9 m)
Deck width32 ft (9.8 m)
Roadway width30 ft (9.2 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic—
Projected traffic—
Trucks0%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed123.7 mi (199 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerState Park, Forest, or Reservation Agency
Maintained byState Park, Forest, or Reservation 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 Backbone State Pk over Br Maquoketa River built?

It was built in 1976, making it 49 years old in 2025.

What condition is Backbone State Pk over Br Maquoketa 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 May 2024.

How much traffic does Backbone State Pk over Br Maquoketa River carry?

No traffic count is recorded for this structure.

How long is Backbone State Pk over Br Maquoketa River?

The structure is 139 ft (42.4 m) long with a longest span of 39 ft (11.9 m) and a deck 32 ft wide.

Who owns Backbone State Pk over Br Maquoketa River?

It is owned by the State Park, Forest, or Reservation Agency.