US Bridges

Back Loop RD over Mendenhall River

Fair

Juneau City and Borough, Alaska · Mile Point 3.2 · Structure no. 0217

Built
1985
40 years old
Condition
Fair
inspected June 2023
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
196 ft
2 main spans
Daily traffic
4,230
2020 count
Owner
State
State Highway Agency

About this bridge

Back Loop RD over Mendenhall River is a prestressed concrete stringer/multi-beam or girder carrying Back Loop RD over Mendenhall River in Juneau City and Borough, Alaska. It was built in 1985, so it is 40 years old, older than the Alaska average of 35.9 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 4,230 vehicles a day, roughly 14% of them trucks, projected to reach 5,400 by 2039. The structure is 196 ft (59.7 m) long and 51 ft wide. If it were closed, the detour would be 9.9 mi (16 km).

Location

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CarriesBack Loop RD
CrossesMendenhall River
LocationMile Point 3.2
RouteState Highway 966
CountyJuneau City and Borough
StateAlaska
Coordinates58.40417, -134.58472
Functional classUrban 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
Deck7 GoodSome minor problems.
Superstructure7 GoodSome minor problems.
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 inspectionJune 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry6: Equal to present minimum criteria
Waterway adequacy9: Superior to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating90.1 US tons
Inventory rating50.4 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans2
Design loadHS 20
Structure length196 ft (59.7 m)
Longest span97 ft (29.6 m)
Deck width51 ft (15.5 m)
Roadway width40 ft (12.2 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic4,230 (2020)
Projected traffic5,400 by 2039
Trucks14%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway and pedestrian
CrossesWaterway
Detour if closed9.9 mi (16 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 Back Loop RD over Mendenhall River built?

It was built in 1985, making it 40 years old in 2025.

What condition is Back Loop RD over Mendenhall 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 June 2023.

How much traffic does Back Loop RD over Mendenhall River carry?

About 4,230 vehicles per day (2020 count), of which roughly 14% are trucks.

How long is Back Loop RD over Mendenhall River?

The structure is 196 ft (59.7 m) long with a longest span of 97 ft (29.6 m) and a deck 51 ft wide.

Who owns Back Loop RD over Mendenhall River?

It is owned by the State Highway Agency.