US016AE

over US016AW

KEYSTONE INTERCHANGE, Pennington County, South Dakota

Condition

Fair

Year Built

1968

Daily Traffic

3,778

Length

29 ft

About This Bridge

US016AE carries traffic over US016AW in Pennington County, South Dakota. Built in 1968, this structure is 58 years old, placing it among the older bridges still in active service. The bridge features wood or timber construction with a arch - deck design, a combination chosen by engineers to meet the specific requirements of this crossing.

Approximately 3,778 vehicles cross this bridge daily, indicating lower traffic volumes common for local roads and rural routes. While traffic is lighter, these bridges still serve essential community transportation needs. Commercial trucks account for 12% of all crossings. This proportion of commercial traffic is typical for this roadway classification and is factored into the bridge's design load ratings.

The bridge is currently rated in fair condition based on federal inspection criteria established by the Federal Highway Administration. The structure meets current safety standards for its designated use and load capacity. With a total length of 29 feet, this is a shorter span typical of local road crossings, often carrying traffic over small streams, drainage channels, or other roadways.

The construction materials used in this bridge were selected based on engineering requirements, cost considerations, and local conditions at the time of construction.

Federal law requires that all highway bridges be inspected at least every 24 months by qualified inspectors following the National Bridge Inspection Standards (NBIS). Some bridges with known issues or unusual characteristics may be inspected more frequently. Inspection data is reported to the National Bridge Inventory, a database maintained by the Federal Highway Administration that tracks the condition of all public highway bridges in the United States. This bridge data is sourced from that federal database and reflects the most recent available inspection results.

Condition Ratings

8

Deck Condition

Very Good

7

Superstructure

Good

6

Substructure

Satisfactory

Channel & Protection

N/A

6

Lowest Rating

Determines condition category

NBI condition ratings range from 0 (failed) to 9 (excellent). Ratings of 4 or below are considered poor. The overall condition category is determined by the lowest individual component rating.

The fair condition rating of 6 indicates satisfactory condition with minor section loss or deterioration.

For a structure built in 1968, this condition level is expected given the bridge's age and usage patterns.

Bridge Details

Wood or Timber is the primary structural material, which influences maintenance requirements and expected lifespan. The arch - deck design was selected based on span requirements, load capacity needs, and site conditions at the time of construction. Maintenance responsibility falls to State Highway Agency.

Construction

Year Built1968
MaterialWood or Timber
Design TypeArch - Deck
OwnerState Highway Agency

Dimensions

Total Length29 ft (8.8 m)
Max Span16 ft (4.7 m)
Deck Width3 ft
Deck Area751 sq ft

Span dimensions affect structural design choices and load distribution. The deck area of 751 sq ft determines surface maintenance scope.

Classification

Route TypeUS Highway
Route Number16
Lanes On Bridge1
Lanes Under Bridge1

Status

Toll BridgeNo
Historical SignificanceEligible for NRHP
Scour CriticalN
Detour Length

Traffic Data

Traffic volume data helps engineers assess bridge wear patterns and plan maintenance schedules. Average Daily Traffic (ADT) counts are updated periodically and represent typical weekday usage.

3,778

Avg Daily Traffic (2023)

Vehicles per day crossing this bridge

12%

Truck Traffic

Commercial vehicle percentage

5,958

Projected Future ADT

Estimated future demand

This bridge carries approximately 3,778 vehicles per day, translating to roughly 1,378,970 crossings annually. Lower traffic volumes generally result in less structural wear over time.

Commercial trucks comprise 12% of traffic. Heavy vehicles cause disproportionate wear—a single fully loaded truck can have the impact of thousands of passenger cars on bridge deck surfaces.

Traffic projections estimate future volumes of 5,958 vehicles daily, a 58% increase from current levels. These projections inform capacity planning and potential upgrade requirements.

Load Ratings

Load ratings determine what weight this bridge can safely support. These values are critical for routing heavy vehicles and issuing overweight permits.

Operating Rating

6.0 tons

Maximum allowable load for special permits

Inventory Rating

4.2 tons

Load level for normal traffic

The operating rating of 6.0 tons represents the absolute maximum load this bridge can carry under controlled conditions with special permits. The inventory rating of 4.2 tons is the safe load limit for everyday traffic without restrictions. These relatively low ratings may result in posted weight limits or route restrictions for heavy vehicles.

5-Year Condition Trend

Declining

Condition has declined by 1.0 rating points since 2020

Data: 2020-2024 FHWA National Bridge Inventory

Location

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44.763333, -104.375833

Identification

Structure Number000000052308412
NBI IDSD-000000052308412
State FIPS46
County FIPS103

Explore More

Data Source: Federal Highway Administration (FHWA) National Bridge Inventory 2024

Bridge inspection data is typically updated every 24 months. Conditions may have changed since the last inspection.

“Structurally deficient” does not mean a bridge is unsafe or likely to collapse. It indicates that one or more key structural elements are in poor or worse condition. Bridges are inspected regularly and may have load restrictions in place.

This data is for informational purposes only and should not be used for route clearance or vehicle weight decisions.

US016AE over US016AW | South Dakota