US Bridges

HWY 100 over Horsetail Falls

Fair

Multnomah County, Oregon · 2.5 MI E Multnomah Falls · Structure no. 04543 125 02221

Built
1914
111 years old
Condition
Fair
inspected September 2023
Type
Slab
Concrete Continuous
Length
60 ft
3 main spans
Daily traffic
901
2022 count
Owner
State
State Highway Agency

About this bridge

HWY 100 over Horsetail Falls is a concrete continuous slab carrying HWY 100 over Horsetail Falls in Multnomah County, Oregon. It was built in 1914, so it is 111 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 901 vehicles a day, roughly 4% of them trucks, projected to reach 1,200 by 2042. The structure is 60 ft (18.3 m) long and 24 ft wide. If it were closed, the detour would be 14.9 mi (24 km).

Location

Open in Google Maps
CarriesHWY 100
CrossesHorsetail Falls
Location2.5 MI E Multnomah Falls
RouteState Highway 30
CountyMultnomah County
StateOregon
Coordinates45.59027, -122.06919
Functional classRural Major 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
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure7 GoodSome minor problems.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Last inspectionSeptember 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry3: Basically intolerable, requiring high priority of corrective action
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating28.2 US tons
Inventory rating21.8 US tons

Structure

Structure typeSlab
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadH 15
Structure length60 ft (18.3 m)
Longest span20 ft (6.1 m)
Deck width24 ft (7.3 m)
Roadway width22 ft (6.6 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic901 (2022)
Projected traffic1,200 by 2042
Trucks4%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed14.9 mi (24 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusListed on the National Register of Historic Places
Work proposedWidening of existing bridge without deck rehabilitation
Estimated improvement cost$307,000
NavigationNo navigation control on waterway

Frequently asked questions

When was HWY 100 over Horsetail Falls built?

It was built in 1914, making it 111 years old in 2025.

What condition is HWY 100 over Horsetail Falls 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 September 2023.

How much traffic does HWY 100 over Horsetail Falls carry?

About 901 vehicles per day (2022 count), of which roughly 4% are trucks.

How long is HWY 100 over Horsetail Falls?

The structure is 60 ft (18.3 m) long with a longest span of 20 ft (6.1 m) and a deck 24 ft wide.

Who owns HWY 100 over Horsetail Falls?

It is owned by the State Highway Agency.