US Bridges

18th ST SW over Drainage Ditch

Poor

Linn County, Iowa · 000000000 · Structure no. 000000000001450

Built
1978
47 years old
Condition
Poor
inspected April 2023
Type
Culvert
Steel
Length
35 ft
2 main spans
Daily traffic
1,494
2022 count
Owner
City
City or Municipal Highway Agency

About this bridge

18th ST SW over Drainage Ditch is a steel culvert carrying 18th ST SW over Drainage Ditch in Linn County, Iowa. It was built in 1978, so it is 47 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 1,494 vehicles a day, projected to reach 1,494 by 2043. The structure is 35 ft (10.7 m) long. If it were closed, the detour would be 3.1 mi (5 km).

Location

Open in Google Maps
Carries18th ST SW
CrossesDrainage Ditch
Location000000000
RouteCity Street 0
CountyLinn County
StateIowa
Coordinates41.94986, -91.69659
Functional classUrban Local

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 protection5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Culvert4 PoorAdvanced section loss, deterioration, spalling or scour.
Last inspectionApril 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourCountermeasures installed to correct a previously existing problem
Structural evaluation4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy6: Equal to present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating34 US tons
Inventory rating25 US tons

Structure

Structure typeCulvert
MaterialSteel
DeckNot applicable
Main spans2
Design loadUnknown
Structure length35 ft (10.7 m)
Longest span14 ft (4.3 m)
Deck width0 ft (0 m)
Roadway width0 ft (0 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic1,494 (2022)
Projected traffic1,494 by 2043
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

OwnerCity or Municipal Highway Agency
Maintained byCity or Municipal Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedOther structural work, including hydraulic replacements
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was 18th ST SW over Drainage Ditch built?

It was built in 1978, making it 47 years old in 2025.

What condition is 18th ST SW over Drainage Ditch 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 April 2023.

How much traffic does 18th ST SW over Drainage Ditch carry?

About 1,494 vehicles per day (2022 count).

How long is 18th ST SW over Drainage Ditch?

The structure is 35 ft (10.7 m) long with a longest span of 14 ft (4.3 m).

Who owns 18th ST SW over Drainage Ditch?

It is owned by the City or Municipal Highway Agency.