I40

over HARPETH RIVER

.4 M E JCT SR249&I40, Cheatham County, Tennessee

Condition

Poor

Year Built

1960

Daily Traffic

53,557

Length

60 ft

About This Bridge

I40 carries traffic over HARPETH RIVER in Cheatham County, Tennessee. Built in 1960, this structure is 66 years old, placing it among the older bridges still in active service. The bridge features prestressed concrete construction with a stringer/multi-beam or girder design, a combination chosen by engineers to meet the specific requirements of this crossing.

Approximately 53,557 vehicles cross this bridge daily, making it a high-traffic corridor critical to regional transportation. Bridges carrying this volume require enhanced inspection schedules and proactive maintenance programs. Commercial trucks account for 7% 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 poor condition based on federal inspection criteria established by the Federal Highway Administration. It is classified as structurally deficient, meaning one or more components have received a rating of 4 or below on the 0-9 scale. This designation indicates significant deterioration that warrants attention, though the bridge remains safe for travel within its posted limits. Structurally deficient does not mean unsafe—rather, it signals that repairs or replacement should be prioritized in transportation planning. With a total length of 60 feet, this is a shorter span typical of local road crossings, often carrying traffic over small streams, drainage channels, or other roadways.

Concrete bridges offer excellent durability and relatively low maintenance requirements. They resist corrosion well but can develop cracking over time, particularly in regions with freeze-thaw cycles or heavy use of deicing chemicals. Regular inspection focuses on detecting cracks, spalling, and reinforcement corrosion.

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

Structurally Deficient

This bridge has one or more component ratings of 4 or below, indicating significant deterioration that requires attention. The bridge remains safe for travel but may have load restrictions.

5

Deck Condition

Fair

5

Superstructure

Fair

4

Substructure

Poor

5

Channel & Protection

Fair

4

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 substructure rating of 4 reflects significant wear in piers, abutments, or foundations.

For a structure built in 1960, the current condition reflects the cumulative effects of age, traffic, and environmental exposure. High traffic volumes on a bridge in fair or poor condition typically elevate its priority for rehabilitation or replacement in state transportation planning.

Bridge Details

Prestressed Concrete is the primary structural material, which influences maintenance requirements and expected lifespan. The stringer/multi-beam or girder 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 Built1960
Year Reconstructed1988
MaterialPrestressed Concrete
Design TypeStringer/Multi-beam or Girder
OwnerState Highway Agency

Dimensions

Total Length60 ft (18.3 m)
Max Span5 ft (1.5 m)
Deck Width4 ft
Deck Area2,447 sq ft

Span dimensions affect structural design choices and load distribution. The deck area of 2,447 sq ft determines surface maintenance scope.

Classification

Route TypeInterstate
Route Number4
Lanes On Bridge2
Lanes Under Bridge

Status

Toll BridgeNo
Historical SignificanceNot determined
Scour Critical8
Detour Length1 mi (2 km)

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.

53,557

Avg Daily Traffic (2021)

Vehicles per day crossing this bridge

7%

Truck Traffic

Commercial vehicle percentage

85,691

Projected Future ADT

Estimated future demand

This bridge carries approximately 53,557 vehicles per day, translating to roughly 19,548,305 crossings annually. This high volume places significant demands on the structure and necessitates frequent inspections.

Commercial trucks comprise 7% 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 85,691 vehicles daily, a 60% 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

4.0 tons

Maximum allowable load for special permits

Inventory Rating

3.1 tons

Load level for normal traffic

The operating rating of 4.0 tons represents the absolute maximum load this bridge can carry under controlled conditions with special permits. The inventory rating of 3.1 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

Stable

Condition has remained relatively stable since 2020

Status Changes

  • Exited poor condition in 2023
  • No longer structurally deficient as of 2023
  • Entered poor condition in 2024
  • Became structurally deficient in 2024

Data: 2020-2024 FHWA National Bridge Inventory

Location

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36.280000, -87.618333

Identification

Structure Number11I00400008
NBI IDTN-11I00400008
State FIPS47
County FIPS021

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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.

I40 over HARPETH RIVER | Tennessee