US Bridges

Tunnel Dam RD over Niangua River

Poor

Camden County, Missouri · S 23 T 37 N R 18 W · Structure no. 17261

Built
1992
33 years old
Condition
Poor
inspected May 2024
Type
Slab
Concrete
Length
127 ft
15 main spans
Daily traffic
70
2023 count
Owner
County
County Highway Agency

About this bridge

Tunnel Dam RD over Niangua River is a concrete slab carrying Tunnel Dam RD over Niangua River in Camden County, Missouri. It was built in 1992, so it is 33 years old, younger than the Missouri average of 45.1 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 70 vehicles a day, roughly 10% of them trucks, projected to reach 137 by 2043. The structure is 127 ft (38.7 m) long and 15 ft wide. If it were closed, the detour would be 24.2 mi (39 km).

Location

Open in Google Maps
CarriesTunnel Dam RD
CrossesNiangua River
LocationS 23 T 37 N R 18 W
RouteCounty Highway 147
CountyCamden County
StateMissouri
Coordinates37.93797, -92.87584
Functional classRural 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
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure4 PoorAdvanced section loss, deterioration, spalling or scour.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionMay 2024
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
Deck geometry7: Better than present minimum criteria
Waterway adequacy4: Meets minimum tolerable limits to be left in place as is
Approach roadway alignment3: Basically intolerable, requiring high priority of corrective action
Operating rating46.6 US tons
Inventory rating27.8 US tons

Structure

Structure typeSlab
MaterialConcrete
DeckConcrete, cast-in-place
Main spans15
Design loadOther
Structure length127 ft (38.7 m)
Longest span8 ft (2.4 m)
Deck width15 ft (4.7 m)
Roadway width15 ft (4.6 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic70 (2023)
Projected traffic137 by 2043
Trucks10%
Lanes on structure1
Traffic directionOne-lane bridge for two-way traffic
CarriesHighway
CrossesWaterway
Detour if closed24.2 mi (39 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCounty Highway Agency
Maintained byCounty Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost$871,000 (2025 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was Tunnel Dam RD over Niangua River built?

It was built in 1992, making it 33 years old in 2025.

What condition is Tunnel Dam RD over Niangua River 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 Tunnel Dam RD over Niangua River carry?

About 70 vehicles per day (2023 count), of which roughly 10% are trucks.

How long is Tunnel Dam RD over Niangua River?

The structure is 127 ft (38.7 m) long with a longest span of 8 ft (2.4 m) and a deck 15 ft wide.

Who owns Tunnel Dam RD over Niangua River?

It is owned by the County Highway Agency.