SD036
Carrying SD036 over SPOKANE CK
3.9 E JCT US 16A, Custer, South Dakota
FHWA NBI inspection record for this structure. Condition ratings, inventory load rating, span, deck width, and average daily traffic refresh annually with each NBI release.
Bridge Snapshot: SD036
The SD036 bridge in Custer, South Dakota carries SD036 over SPOKANE CK. It was built in 1991, making it 35 years old today. The structure is built primarily of concrete continuous and spans 3 sections, stretching 12.5 meters (41 feet) end to end. Daily traffic averages 730 vehicles, placing it in the lower-traffic tier of South Dakota bridges. It is owned and maintained by State Highway Agency, the entity responsible for routine inspections and any needed repairs.
The latest FHWA inspection records show culvert at 8/9 on the 0–9 NBI scale, where 9 is excellent and 0 is failed. The weakest component sits in good condition, which drives the overall status of this bridge. No major component scores in the poor range, so the bridge is not classified as structurally deficient under federal criteria. Its NBI inventory load rating is 70.6 metric tons — the load level the structure is rated to carry at inventory (long-term) level.
In a county that maintains hundreds of NBI-tracked bridges, SD036 is one data point in a South Dakota inventory that FHWA inspects on a two-year cycle (more often when ratings fall). Bridge age alone is not a reliable safety signal — a 35-era structure can outperform a newer one when maintenance is consistent, materials are sound, and traffic loads stay within design limits. Use the condition ratings above, the sufficiency score, and the structurally-deficient flag together to read the bridge's real status, and check the linked county and state pages to see how this bridge ranks against its peers.
Every figure on this page comes directly from the Federal Highway Administration National Bridge Inventory (NBI), the public dataset that catalogs more than 617,000 highway bridges across the United States and is updated annually from the records that each state Department of Transportation submits to the FHWA. The condition codes use the standardized FHWA Recording and Coding Guide, the same scale that determines federal eligibility for the Highway Bridge Program and the Surface Transportation Block Grant set-aside for off-system bridges. A "structurally deficient" classification under those federal criteria is a maintenance and funding flag, never a closure order; states keep deficient bridges open with load posting, weight limits, or accelerated inspection cycles until rehabilitation or replacement is funded. See our methodology for refresh cadence and the exact NBI release vintage powering each record.
How SD036 compares
NBI inventory load rating (metric tons) and structural-deficiency status compared across South Dakota, computed live from the FHWA NBI.
Condition Ratings
Ratings are on a 0–9 scale: 9 = Excellent, 7–8 = Good, 5–6 = Fair, 3–4 = Poor, 0–2 = Critical/Failed. Sufficiency rating (0–100) combines structural adequacy, functional obsolescence, and essentiality.
Structural Details
- Year Built
- 1991
- Material
- Concrete Continuous
- Number of Spans
- 3
- Structure Length
- 12.5 m (41 ft)
- Owner
- State Highway Agency
- Avg Daily Traffic
- 730 vehicles/day
- Structure Number
- 000000017389047
Location
Data Source
Data from the FHWA National Bridge Inventory (NBI). Bridge inspections are required every two years by federal law. Conditions reflect the most recent inspection.
FHWA NBI Program ↗Guides
Frequently Asked Questions
What do the condition ratings mean for SD036?
Bridge condition ratings use a 0–9 scale set by the Federal Highway Administration (FHWA). Ratings 7–9 indicate good condition with no significant problems. Ratings 5–6 mean fair condition with minor issues. Ratings 3–4 indicate poor condition requiring repair. Ratings 0–2 are critical, meaning the bridge has serious structural problems. SD036 in Custer, South Dakota.
How often is SD036 inspected?
Federal law requires most highway bridges to be inspected at least every 24 months. Bridges in poor condition or with known issues may be inspected more frequently (every 12 months or less). SD036 is part of the National Bridge Inventory maintained by the FHWA. With 730 vehicles crossing daily, regular inspection is essential.
What does "structurally deficient" mean for a bridge?
A structurally deficient bridge has at least one major component (deck, superstructure, or substructure) rated 4 or below on the FHWA 0–9 scale. This classification does NOT mean the bridge is unsafe for travel — it means the bridge needs repair, rehabilitation, or eventual replacement. Structurally deficient bridges remain open and are monitored. SD036 is not classified as structurally deficient.
What is the inventory load rating for SD036?
The NBI inventory rating is the load level a bridge is rated to carry for an indefinite period, recorded in metric tons. A lower number means the structure is more load-restricted. SD036 has an inventory load rating of 70.6 metric tons. It is distinct from the FHWA sufficiency rating, a separate 0–100 funding-eligibility score that this dataset does not include.
Who is responsible for maintaining SD036?
Bridge ownership and maintenance responsibility varies — bridges may be owned by state DOTs, counties, cities, railroads, or federal agencies. SD036 is maintained by State Highway Agency. The FHWA oversees the National Bridge Inventory program and sets inspection standards, but day-to-day maintenance falls to the owning agency. If you notice damage or safety concerns, contact your state DOT or call 911 for emergencies.
How old is SD036 and does age affect safety?
SD036 was built in 1991, making it 35 years old. Bridge age alone does not determine safety — condition depends on materials, design, traffic load, maintenance history, and environmental exposure. Many older bridges remain in good condition due to regular maintenance and reconstruction.
Disclaimer: Bridge condition data is from the FHWA NBI and reflects the last reported inspection. A structurally deficient rating does not mean a bridge is closed or unsafe for travel — it indicates the bridge requires repair or replacement. For current closure or safety information, contact your state DOT.
Read our methodology — how this data is sourced, computed, and verified.
Related
| Publisher | Kiznis Studio |
| Sources | FHWA National Bridge Inventory, public U.S. government datasets |