US Bridges

Mystic Road over Castle Ck

Fair

Pennington County, South Dakota · 0.3W 0.6S Mystic · Structure no. 000000052205309

Built
1940
85 years old
Condition
Fair
inspected June 2023
Type
Stringer/Multi-beam or Girder
Wood or Timber
Length
27 ft
1 main span
Daily traffic
128
2022 count
Owner
County
County Highway Agency

About this bridge

Mystic Road over Castle Ck is a wood or timber stringer/multi-beam or girder carrying Mystic Road over Castle Ck in Pennington County, South Dakota. It was built in 1940, so it is 85 years old, older than the South Dakota average of 48.9 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 128 vehicles a day, roughly 3% of them trucks, projected to reach 128 by 2033. The structure is 27 ft (8.2 m) long and 20 ft wide. If it were closed, the detour would be 18 mi (29 km).

Location

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CarriesMystic Road
CrossesCastle Ck
Location0.3W 0.6S Mystic
RouteCounty Highway 0
CountyPennington County
StateSouth Dakota
Coordinates44.06925, -103.6468
Functional classRural Major 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
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 protection7 GoodSome minor problems.
Last inspectionJune 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourUnknown foundation; not evaluated for scour
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry3: Basically intolerable, requiring high priority of corrective action
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating35.3 US tons
Inventory rating25.8 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialWood or Timber
DeckWood or timber
Main spans1
Design loadH 10
Structure length27 ft (8.2 m)
Longest span25 ft (7.6 m)
Deck width20 ft (6.2 m)
Roadway width19 ft (5.9 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic128 (2022)
Projected traffic128 by 2033
Trucks3%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed18 mi (29 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCounty Highway Agency
Maintained byCounty 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 Mystic Road over Castle Ck built?

It was built in 1940, making it 85 years old in 2025.

What condition is Mystic Road over Castle Ck 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 Mystic Road over Castle Ck carry?

About 128 vehicles per day (2022 count), of which roughly 3% are trucks.

How long is Mystic Road over Castle Ck?

The structure is 27 ft (8.2 m) long with a longest span of 25 ft (7.6 m) and a deck 20 ft wide.

Who owns Mystic Road over Castle Ck?

It is owned by the County Highway Agency.