US Bridges

Walnut ST over Monkey Run

Fair

Louisa County, Iowa · 075041901 · Structure no. 000000000002470

Built
1935
90 years old
Condition
Fair
inspected May 2024
Type
Arch - Deck
Concrete
Length
50 ft
1 main span
Daily traffic
1,140
2022 count
Owner
City
City or Municipal Highway Agency

About this bridge

Walnut ST over Monkey Run is a concrete arch - deck carrying Walnut ST over Monkey Run in Louisa County, Iowa. It was built in 1935, so it is 90 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 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 1,140 vehicles a day, projected to reach 1,140 by 2044. The structure is 50 ft (15.2 m) long and 50 ft wide. If it were closed, the detour would be 1.9 mi (3 km).

Location

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CarriesWalnut ST
CrossesMonkey Run
Location075041901
RouteCity Street 0
CountyLouisa County
StateIowa
Coordinates41.28012, -91.36444
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
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Culvert5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Last inspectionMay 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Deck geometry9: Superior to present desirable criteria
Waterway adequacy6: Equal to present minimum criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating34 US tons
Inventory rating25 US tons

Structure

Structure typeArch - Deck
MaterialConcrete
DeckConcrete, cast-in-place
Main spans1
Design loadUnknown
Structure length50 ft (15.2 m)
Longest span50 ft (15.2 m)
Deck width50 ft (15.2 m)
Roadway width47 ft (14.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic1,140 (2022)
Projected traffic1,140 by 2044
Trucks0%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed1.9 mi (3 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCity or Municipal Highway Agency
Maintained byCity or Municipal Highway Agency
Historic statusPossibly eligible for the National Register; requires further investigation
Work proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost$55,000
NavigationNo navigation control on waterway

Frequently asked questions

When was Walnut ST over Monkey Run built?

It was built in 1935, making it 90 years old in 2025.

What condition is Walnut ST over Monkey Run 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 Walnut ST over Monkey Run carry?

About 1,140 vehicles per day (2022 count).

How long is Walnut ST over Monkey Run?

The structure is 50 ft (15.2 m) long with a longest span of 50 ft (15.2 m) and a deck 50 ft wide.

Who owns Walnut ST over Monkey Run?

It is owned by the City or Municipal Highway Agency.