US Bridges

Main RD over Mill Brook

Fair

Penobscot County, Maine · 100 Ft W of JCT RTE 46 · Structure no. 5107

Built
1922
103 years old, rebuilt 1961
Condition
Fair
inspected October 2024
Type
Tee Beam
Concrete
Length
34 ft
1 main span
Daily traffic
4,216
2016 count
Owner
State
State Highway Agency

About this bridge

Main RD over Mill Brook is a concrete tee beam carrying Main RD over Mill Brook in Penobscot County, Maine. It was built in 1922 and reconstructed in 1961, so it is 103 years old, older than the Maine average of 53.7 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 4,216 vehicles a day, roughly 5% of them trucks, projected to reach 5,902 by 2036. The structure is 34 ft (10.3 m) long and 43 ft wide. If it were closed, the detour would be 100 mi (161 km).

Location

Open in Google Maps
CarriesMain RD
CrossesMill Brook
Location100 Ft W of JCT RTE 46
RouteState Highway 9
CountyPenobscot County
StateMaine
Coordinates44.79185, -68.58273
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
Deck5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
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 inspectionOctober 2024
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 geometry6: Equal to present minimum criteria
Waterway adequacy9: Superior to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating73.9 US tons
Inventory rating56.7 US tons

Structure

Structure typeTee Beam
MaterialConcrete
DeckConcrete, cast-in-place
Main spans1
Design loadHS 20
Structure length34 ft (10.3 m)
Longest span30 ft (9.1 m)
Deck width43 ft (13 m)
Roadway width40 ft (12.2 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic4,216 (2016)
Projected traffic5,902 by 2036
Trucks5%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed100 mi (161 km)
TollOn a free road
National Highway SystemYes

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusHistorical significance not determinable at this time
Work proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was Main RD over Mill Brook built?

It was built in 1922, making it 103 years old in 2025. It was reconstructed in 1961.

What condition is Main RD over Mill Brook 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 Main RD over Mill Brook carry?

About 4,216 vehicles per day (2016 count), of which roughly 5% are trucks.

How long is Main RD over Mill Brook?

The structure is 34 ft (10.3 m) long with a longest span of 30 ft (9.1 m) and a deck 43 ft wide.

Who owns Main RD over Mill Brook?

It is owned by the State Highway Agency.