US Bridges

US101 (hwy 9) over Neahkahnie Mt. Chasm

FairPosted for load

Tillamook County, Oregon · 016 MI S Short Sands Bch · Structure no. 02723 009 04071

Built
1937
88 years old
Condition
Fair
inspected October 2024
Type
Girder and Floorbeam System
Concrete Continuous
Length
103 ft
1 main span
Daily traffic
5,743
2022 count
Owner
State
State Highway Agency

About this bridge

US101 (hwy 9) over Neahkahnie Mt. Chasm is a concrete continuous girder and floorbeam system carrying US101 (hwy 9) over Neahkahnie Mt. Chasm in Tillamook County, Oregon. It was built in 1937, so it is 88 years old, older than the Oregon average of 49.9 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. Its operating status is: posted for other load-capacity restriction.

It carries about 5,743 vehicles a day, roughly 12% of them trucks, projected to reach 7,560 by 2042. The structure is 103 ft (31.5 m) long and 37 ft wide. If it were closed, the detour would be 6.2 mi (10 km).

Location

Open in Google Maps
CarriesUS101 (hwy 9)
CrossesNeahkahnie Mt. Chasm
Location016 MI S Short Sands Bch
RouteU.S. Route 101
CountyTillamook County
StateOregon
Coordinates45.74332, -123.9576
Functional classRural Principal Arterial - Other

Condition and inspection

Fair

The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

ComponentRatingMeaning
Deck8 Very GoodNo problems noted.
Superstructure7 GoodSome minor problems.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionOctober 2024
Inspection intervalevery 24 months
Operating statusPosted for other load-capacity restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation3: Basically intolerable, requiring high priority of corrective action
Deck geometry3: Basically intolerable, requiring high priority of corrective action
Approach roadway alignment8: Equal to present desirable criteria
Operating rating21.4 US tons
Inventory rating16.8 US tons

Structure

Structure typeGirder and Floorbeam System
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans1 (+4 approach)
Design loadH 15
Structure length103 ft (31.5 m)
Longest span59 ft (18 m)
Deck width37 ft (11.4 m)
Roadway width30 ft (9.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic5,743 (2022)
Projected traffic7,560 by 2042
Trucks12%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesOther
Detour if closed6.2 mi (10 km)
TollOn a free road
National Highway SystemYes
Strategic Highway NetworkNon-Interstate STRAHNET route

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusEligible for the National Register of Historic Places
Work proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was US101 (hwy 9) over Neahkahnie Mt. Chasm built?

It was built in 1937, making it 88 years old in 2025.

What condition is US101 (hwy 9) over Neahkahnie Mt. Chasm 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 October 2024.

How much traffic does US101 (hwy 9) over Neahkahnie Mt. Chasm carry?

About 5,743 vehicles per day (2022 count), of which roughly 12% are trucks.

How long is US101 (hwy 9) over Neahkahnie Mt. Chasm?

The structure is 103 ft (31.5 m) long with a longest span of 59 ft (18 m) and a deck 37 ft wide.

Who owns US101 (hwy 9) over Neahkahnie Mt. Chasm?

It is owned by the State Highway Agency.