OKI NHS Bridge Condition by Deck Area

Now compute the FHWA Good/Fair/Poor classification (lowest of deck, superstructure, substructure; culvert rating for culverts), weighted by deck area.

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NHS bridge condition in the OKI region, weighted by deck area

Scope: I counted bridges that ODOT codes to the OKI MPO (MPO code 09, the Ohio side of OKI: Hamilton, Butler, Warren and Clermont counties). Each one carries a National Highway System route (NBI item 104 = 1), meets the NBIS minimum bridge length, and is an "on" record. That comes to 459 structures and about 8.49 million sq ft of deck.

Method: I used the FHWA performance-measure rule. Each bridge is rated by its lowest NBI component rating: deck, superstructure or substructure, or the culvert rating (item 62) for culverts. A lowest rating of 7 or higher is Good, 4 or lower is Poor, and 5–6 is Fair.

Only 1.3% of NHS deck area is Poor, well below the federal 10% poor-deck-area penalty threshold. The more notable figure is the Fair share: 43% of deck area, much higher than its 34% share of bridges. Large structures are more likely to be Fair, so a lot of the region's deck area is one rating drop away from Poor.

The six Poor structures, by traffic (NBI item 29 ADT)

What stands out:

• The I-75 ramp culvert at Dick's Creek has the most traffic. It's small, but its 91k ADT is almost certainly the traffic on the I-75 route it's recorded against, not what the ramp itself carries. Its future-traffic forecast is 127k.
• The I-275 twin bridges at Loveland Rd are the biggest Poor exposure. Both directions are rated Poor, each carries about 35.7k ADT, and together they make up about 45k sq ft of the 113k sq ft Poor total.
• All five I-275 bridges are Poor for the same reason: superstructure = 4. Their decks rate 6–7 and their substructures 6–7. They were built in 1970–76, and all are ODOT-maintained and open without restrictions.
• The three I-275 bridges on Cincinnati's west side (Whitewater River and US 50 / railroad) sit together and carry about 16k ADT each. They could be packaged as one corridor project.

OKI NHS Bridge Condition by Deck Area⬇ Image

Map legend:

• Grey outline: the OKI MPO boundary.
• Points: NHS bridges, coloured by condition. Green is Good, amber is Fair, and red with a heavy outline is Poor.
• Click any point to see its SFN, route, lowest rating, deck area and ADT.

Caveats:

• What's left out: Kentucky and Indiana bridges in the OKI region aren't in this Ohio inventory. Border bridges that Kentucky maintains, such as the Ohio River crossings, may also be missing or only partly included.
• Boundary choice: Using the MPO polygon instead of the MPO code gives 556 rather than 566 NHS records before filtering. That's a small difference.
• Next steps: I can list the Fair structures rated 5 that are close to becoming Poor, or check which Poor bridges already have projects in the STIP or the next-4-years program.