US Bridges

Old Mamalahoa HWY over Mahuna Gulch

FairPosted for load

Hawaii County, Hawaii · Tmk 4-2-02:19 · Structure no. 001420001100002

Built
1930
95 years old, rebuilt 1988
Condition
Fair
inspected May 2023
Type
Stringer/Multi-beam or Girder
Wood or Timber
Length
47 ft
4 main spans
Daily traffic
40
1987 count
Owner
County
County Highway Agency

About this bridge

Old Mamalahoa HWY over Mahuna Gulch is a wood or timber stringer/multi-beam or girder carrying Old Mamalahoa HWY over Mahuna Gulch in Hawaii County, Hawaii. It was built in 1930 and reconstructed in 1988, so it is 95 years old, older than the Hawaii average of 63.8 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. Its operating status is: posted for load restriction.

It carries about 40 vehicles a day, projected to reach 50 by 2025. The structure is 47 ft (14.3 m) long and 16 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

Open in Google Maps
CarriesOld Mamalahoa HWY
CrossesMahuna Gulch
LocationTmk 4-2-02:19
RouteCounty Highway 0
CountyHawaii County
StateHawaii
Coordinates20.02515, -155.33465
Functional classRural Local

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 protection7 GoodSome minor problems.
Last inspectionMay 2023
Inspection intervalevery 24 months
Operating statusPosted for load restriction
ScourFoundations stable; scour above top of footing
Structural evaluation3: Basically intolerable, requiring high priority of corrective action
Deck geometry7: Better than present minimum criteria
Waterway adequacy9: Superior to present desirable criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating13.9 US tons
Inventory rating10.7 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialWood or Timber
DeckWood or timber
Main spans4
Design loadUnknown
Structure length47 ft (14.3 m)
Longest span17 ft (5.3 m)
Deck width16 ft (4.9 m)
Roadway width15 ft (4.6 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic40 (1987)
Projected traffic50 by 2025
Trucks0%
Lanes on structure1
Traffic directionOne-lane bridge for two-way traffic
CarriesHighway
CrossesRelief for waterway
Detour if closed1.2 mi (2 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 proposedOther structural work, including hydraulic replacements
Estimated improvement cost$320,000
NavigationNot applicable (no waterway)

Frequently asked questions

When was Old Mamalahoa HWY over Mahuna Gulch built?

It was built in 1930, making it 95 years old in 2025. It was reconstructed in 1988.

What condition is Old Mamalahoa HWY over Mahuna Gulch 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 May 2023.

How much traffic does Old Mamalahoa HWY over Mahuna Gulch carry?

About 40 vehicles per day (1987 count).

How long is Old Mamalahoa HWY over Mahuna Gulch?

The structure is 47 ft (14.3 m) long with a longest span of 17 ft (5.3 m) and a deck 16 ft wide.

Who owns Old Mamalahoa HWY over Mahuna Gulch?

It is owned by the County Highway Agency.