US Bridges

FM 170 ST over Small Stream

Poor

Delaware County, Iowa · 089040807 · Structure no. 000000000141480

Built
1955
70 years old
Condition
Poor
inspected May 2024
Type
Culvert
Concrete
Length
22 ft
2 main spans
Daily traffic
79
2022 count
Owner
County
County Highway Agency

About this bridge

FM 170 ST over Small Stream is a concrete culvert carrying FM 170 ST over Small Stream in Delaware County, Iowa. It was built in 1955, so it is 70 years old, older than the Iowa average of 45.5 years.

The most recent inspection reported to the Federal Highway Administration rates it in poor condition with a lowest component rating of 4 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 79 vehicles a day, projected to reach 79 by 2044. The structure is 22 ft (6.7 m) long and 26 ft wide. If it were closed, the detour would be 3.1 mi (5 km).

Location

Open in Google Maps
CarriesFM 170 ST
CrossesSmall Stream
Location089040807
RouteCounty Highway 0
CountyDelaware County
StateIowa
Coordinates42.54276, -91.33825
Functional classRural Minor 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 protection6 SatisfactoryStructural elements show some minor deterioration.
Culvert4 PoorAdvanced section loss, deterioration, spalling or scour.
Last inspectionMay 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation4: Meets minimum tolerable limits to be left in place as is
Deck geometry6: Equal to present minimum criteria
Waterway adequacy6: Equal to present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating25.6 US tons
Inventory rating18.7 US tons

Structure

Structure typeCulvert
MaterialConcrete
DeckNot applicable
Main spans2
Design loadH 15
Structure length22 ft (6.7 m)
Longest span11 ft (3.4 m)
Deck width26 ft (7.9 m)
Roadway width24 ft (7.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic79 (2022)
Projected traffic79 by 2044
Trucks0%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed3.1 mi (5 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCounty Highway Agency
Maintained byCounty Highway Agency
Historic statusPossibly eligible for the National Register; requires further investigation
Work proposedRehabilitation because of general structure deterioration or inadequate strength
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was FM 170 ST over Small Stream built?

It was built in 1955, making it 70 years old in 2025.

What condition is FM 170 ST over Small Stream 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 May 2024.

How much traffic does FM 170 ST over Small Stream carry?

About 79 vehicles per day (2022 count).

How long is FM 170 ST over Small Stream?

The structure is 22 ft (6.7 m) long with a longest span of 11 ft (3.4 m) and a deck 26 ft wide.

Who owns FM 170 ST over Small Stream?

It is owned by the County Highway Agency.