Structure 14693 · Dauphin County, PA

Deibler Gap T-474 over Mahantango Creek

Carries Deibler Gap T-474 over Mahantango Creek, Seaman Bridge.

Overall conditionPoor

Set by its lowest-rated component: Deck and Superstructure at 1 of 9.

How ratings work
Decksets the rating1/9 · Imminent Failure
Superstructuresets the rating1/9 · Imminent Failure
Substructure5/9 · Fair
Channelnot part of overall5/9 · Fair
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT168 FT OVERALL25 FT0ELEVATION · LENGTHS TO SCALE
Deck 1/9 · sets the ratingSuperstructure 1/9 · sets the ratingSubstructure 5/9

168 ft end to end: about 2 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 through truss.

Built1900126 years old
Length168.0 ft51.2 m
Last inspectedAugust 2023every 24 months

Location

StatePennsylvania
CountyDauphin
LocationSeaman Bridge
CarriesDeibler Gap T-474
CrossesMahantango Creek
Coordinates40.62577, -76.85575

Physical Characteristics

MaterialSteel
DesignTruss - Thru
Total Length168.0 ft (51.2 m)
Max Span162.1 ft (49.4 m)
Deck Width16.1 ft (4.9 m)
Deck Area250.9 sq m
Main Spans1
Year Built1900

Traffic

Lanes On Bridge1

Inspection & Ownership

Last InspectionAugust 2023
Inspection FrequencyEvery 24 months
OwnerCounty Highway Agency
Historical SignificanceBridge is on the National Register of Historic Places
Scour Critical4 — Foundations need monitoring
Structure Number000000000014693

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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