US Bridges

Or 99W (hwy 91) over Long Tom River

Fair

Benton County, Oregon · In Monroe · Structure no. 01587A01W 10116

Built
1954
71 years old
Condition
Fair
inspected April 2023
Type
Tee Beam
Concrete Continuous
Length
230 ft
4 main spans
Daily traffic
6,054
2022 count
Owner
State
State Highway Agency

About this bridge

Or 99W (hwy 91) over Long Tom River is a concrete continuous tee beam carrying Or 99W (hwy 91) over Long Tom River in Benton County, Oregon. It was built in 1954, so it is 71 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 5 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 6,054 vehicles a day, roughly 17% of them trucks, projected to reach 6,200 by 2042. The structure is 230 ft (70.1 m) long and 39 ft wide. If it were closed, the detour would be 4.3 mi (7 km).

Location

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CarriesOr 99W (hwy 91)
CrossesLong Tom River
LocationIn Monroe
RouteState Highway 99
CountyBenton County
StateOregon
Coordinates44.31307, -123.29608
Functional classRural Minor Arterial

Condition and inspection

Fair

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

ComponentRatingMeaning
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionApril 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation3: Basically intolerable, requiring high priority of corrective action
Deck geometry4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating16.8 US tons
Inventory rating12.9 US tons

Structure

Structure typeTee Beam
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans4
Design loadHS 20
Structure length230 ft (70.1 m)
Longest span70 ft (21.3 m)
Deck width39 ft (11.9 m)
Roadway width30 ft (9.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic6,054 (2022)
Projected traffic6,200 by 2042
Trucks17%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway and pedestrian
CrossesWaterway
Detour if closed4.3 mi (7 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

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

Frequently asked questions

When was Or 99W (hwy 91) over Long Tom River built?

It was built in 1954, making it 71 years old in 2025.

What condition is Or 99W (hwy 91) over Long Tom River 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 April 2023.

How much traffic does Or 99W (hwy 91) over Long Tom River carry?

About 6,054 vehicles per day (2022 count), of which roughly 17% are trucks.

How long is Or 99W (hwy 91) over Long Tom River?

The structure is 230 ft (70.1 m) long with a longest span of 70 ft (21.3 m) and a deck 39 ft wide.

Who owns Or 99W (hwy 91) over Long Tom River?

It is owned by the State Highway Agency.