US Bridges

US 87-E Main ST over Mill Ditch

FairPosted for load

Fergus County, Montana · Lewistown-E Main ST · Structure no. P00057082+02191

Built
1922
103 years old
Condition
Fair
inspected March 2023
Type
Tee Beam
Concrete
Length
25 ft
1 main span
Daily traffic
8,747
2023 count
Owner
State
State Highway Agency

About this bridge

US 87-E Main ST over Mill Ditch is a concrete tee beam carrying US 87-E Main ST over Mill Ditch in Fergus County, Montana. It was built in 1922, so it is 103 years old, older than the Montana average of 47 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 8,747 vehicles a day, roughly 1% of them trucks, projected to reach 9,184 by 2043. The structure is 25 ft (7.6 m) long and 76 ft wide. If it were closed, the detour would be 123.7 mi (199 km).

Location

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CarriesUS 87-E Main ST
CrossesMill Ditch
LocationLewistown-E Main ST
RouteU.S. Route 87
CountyFergus County
StateMontana
Coordinates47.06849, -109.42142
Functional classUrban Other Principal 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
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 protection8 Very GoodNo problems noted.
Last inspectionMarch 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 geometry9: Superior to present desirable criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating22 US tons
Inventory rating17 US tons

Structure

Structure typeTee Beam
MaterialConcrete
DeckConcrete, cast-in-place
Main spans1
Design loadH 15
Structure length25 ft (7.6 m)
Longest span25 ft (7.6 m)
Deck width76 ft (23.2 m)
Roadway width54 ft (16.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic8,747 (2023)
Projected traffic9,184 by 2043
Trucks1%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway and pedestrian
CrossesWaterway
Detour if closed123.7 mi (199 km)
TollOn a free road
National Highway SystemYes

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 US 87-E Main ST over Mill Ditch built?

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

What condition is US 87-E Main ST over Mill Ditch 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 March 2023.

How much traffic does US 87-E Main ST over Mill Ditch carry?

About 8,747 vehicles per day (2023 count), of which roughly 1% are trucks.

How long is US 87-E Main ST over Mill Ditch?

The structure is 25 ft (7.6 m) long with a longest span of 25 ft (7.6 m) and a deck 76 ft wide.

Who owns US 87-E Main ST over Mill Ditch?

It is owned by the State Highway Agency.