US Bridges

Forby RD over Flat CR

Fair

St. Louis County, Missouri · S 36 T 44 N R 3 E · Structure no. 31357

Built
2006
19 years old
Condition
Fair
inspected November 2023
Type
Culvert
Concrete
Length
56 ft
3 main spans
Daily traffic
1,192
2023 count
Owner
City
City or Municipal Highway Agency

About this bridge

Forby RD over Flat CR is a concrete culvert carrying Forby RD over Flat CR in St. Louis County, Missouri. It was built in 2006, so it is 19 years old, younger than the Missouri average of 45.1 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.

It carries about 1,192 vehicles a day, roughly 2% of them trucks, projected to reach 1,609 by 2043. The structure is 56 ft (17.2 m) long. If it were closed, the detour would be 3.1 mi (5 km).

Location

Open in Google Maps
CarriesForby RD
CrossesFlat CR
LocationS 36 T 44 N R 3 E
RouteCity Street 135
CountySt. Louis County
StateMissouri
Coordinates38.51642, -90.63781
Functional classUrban Collector

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.
Culvert6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionNovember 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Waterway adequacy9: Superior to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating62.5 US tons
Inventory rating41.7 US tons

Structure

Structure typeCulvert
MaterialConcrete
DeckNot applicable
Main spans3
Design loadHS 20
Structure length56 ft (17.2 m)
Longest span18 ft (5.5 m)
Deck width0 ft (0 m)
Roadway width0 ft (0 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic1,192 (2023)
Projected traffic1,609 by 2043
Trucks2%
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 statusHistorical significance not determinable at this time
Work proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was Forby RD over Flat CR built?

It was built in 2006, making it 19 years old in 2025.

What condition is Forby RD over Flat CR 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 November 2023.

How much traffic does Forby RD over Flat CR carry?

About 1,192 vehicles per day (2023 count), of which roughly 2% are trucks.

How long is Forby RD over Flat CR?

The structure is 56 ft (17.2 m) long with a longest span of 18 ft (5.5 m).

Who owns Forby RD over Flat CR?

It is owned by the City or Municipal Highway Agency.