US Bridges

NW 128th ST NB over Walnut Creek

Good

Polk County, Iowa · 079253200 · Structure no. 000000000504850

Built
2007
18 years old
Condition
Good
inspected May 2023
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
247 ft
3 main spans
Daily traffic
6,875
2021 count
Owner
City
City or Municipal Highway Agency

About this bridge

NW 128th ST NB over Walnut Creek is a prestressed concrete stringer/multi-beam or girder carrying NW 128th ST NB over Walnut Creek in Polk County, Iowa. It was built in 2007, so it is 18 years old, younger than the Iowa average of 45.5 years.

The most recent inspection reported to the Federal Highway Administration rates it in good condition with a lowest component rating of 7 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

It carries about 6,875 vehicles a day, roughly 1% of them trucks, projected to reach 6,875 by 2043. The structure is 247 ft (75.4 m) long and 41 ft wide.

Location

Open in Google Maps
CarriesNW 128th ST NB
CrossesWalnut Creek
Location079253200
RouteCity Street 0
CountyPolk County
StateIowa
Coordinates41.61263, -93.79296
Functional classUrban Minor Arterial

Condition and inspection

Good

All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

ComponentRatingMeaning
Deck7 GoodSome minor problems.
Superstructure8 Very GoodNo problems noted.
Substructure7 GoodSome minor problems.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionMay 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation7: Better than present minimum criteria
Deck geometry4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating74.6 US tons
Inventory rating44.6 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20
Structure length247 ft (75.4 m)
Longest span82 ft (25 m)
Deck width41 ft (12.5 m)
Roadway width32 ft (9.8 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic6,875 (2021)
Projected traffic6,875 by 2043
Trucks1%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed—
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 proposedRehabilitation because of general structure deterioration or inadequate strength
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was NW 128th ST NB over Walnut Creek built?

It was built in 2007, making it 18 years old in 2025.

What condition is NW 128th ST NB over Walnut Creek in?

The National Bridge Inventory rates it in good condition. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted. The last reported inspection was in May 2023.

How much traffic does NW 128th ST NB over Walnut Creek carry?

About 6,875 vehicles per day (2021 count), of which roughly 1% are trucks.

How long is NW 128th ST NB over Walnut Creek?

The structure is 247 ft (75.4 m) long with a longest span of 82 ft (25 m) and a deck 41 ft wide.

Who owns NW 128th ST NB over Walnut Creek?

It is owned by the City or Municipal Highway Agency.