Structure 6066735 · Morton County, ND

Nd Highway 6 over Heart River

Carries Nd Highway 6 over Heart River, 1 South Of Mandan.

Overall conditionGood

Set by its lowest-rated component: Deck and Superstructure and Substructure at 7 of 9.

How ratings work
Decksets the rating7/9 · Good
Superstructuresets the rating7/9 · Good
Substructuresets the rating7/9 · Good
Channelnot part of overall6/9 · Satisfactory
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT316 FT OVERALL50 FT0ELEVATION · LENGTHS TO SCALE
Deck 7/9Superstructure 7/9Substructure 7/9

316 ft end to end, longest span 133 ft: about 4 semi-trucks nose to tail. Lengths and the semi-truck on the deck are drawn to the same scale. Each part is colored by its latest inspection rating. The inventory records lengths but not heights or the layout of the shorter spans, so those are drawn as typical for a multi-beam bridge.

Built198442 years old
Length315.9 ft96.3 m
Daily traffic3,550counted 2019
Last inspectedJuly 2023every 24 months

Location

StateNorth Dakota
CountyMorton
Location1 South Of Mandan
CarriesNd Highway 6
CrossesHeart River
Coordinates46.81461, -100.90488

Physical Characteristics

MaterialSteel Continuous
DesignStringer/Multi-beam
Total Length315.9 ft (96.3 m)
Max Span132.9 ft (40.5 m)
Deck Width55.4 ft (16.9 m)
Deck Area1627.5 sq m
Main Spans3
Year Built1984

Traffic

Avg Daily Traffic3,550 (2019)
Truck Traffic6%
Lanes On Bridge2

Inspection & Ownership

Last InspectionJuly 2023
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour Critical8 — Stable, low risk
Structure Number0006066735

How Bridge Ratings Work

Inspectors rate each major part of a bridge (the deck you drive on, the superstructure of beams that holds it up, and the substructure of piers and abutments beneath) on a 0–9 scale. A bridge's overall condition is its lowest of those ratings, so one deteriorated component makes the whole bridge "poor."

0Failed
1Imminent failure
2Critical
3Serious
4Poor
5Fair
6Satisfactory
7Good
8Very good
9Excellent
Good · lowest component 7–9
Fair · lowest component 5–6
Poor · lowest component 0–4

A poor rating is not a closure. It means the bridge is flagged for priority repair or replacement; bridges judged unsafe are closed or posted with weight limits. The waterway (channel) rating is reported, but it does not count toward the overall classification.

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