Add dataset card for salt

README.md

@@ -0,0 +1,87 @@
+---
+license: cc-by-4.0
+language:
+  - en
+tags:
+  - bridge
+  - infrastructure
+  - road-salt
+  - deterioration
+  - civil-engineering
+  - united-states
+pretty_name: Bridgedeck — Road Salt Exposure (USGS)
+size_categories:
+  - n<1K
+---
+
+# Bridgedeck — Road Salt Exposure (USGS)
+
+Part of the **bridgedeck** dataset collection for US bridge deck deterioration research.
+
+## Overview
+
+State-level road salt (deicing salt) tier classification for all 50 US states + DC,
+derived from USGS estimates of road salt application across the conterminous United States.
+
+Road salt is the strongest predictor of bridge deck deterioration in the bridgedeck
+XGBoost model (gain importance: `salt_proportion`=0.114, `salt_tier`=0.086), even as
+a static state-level proxy. Chloride from deicing salt penetrates concrete and
+accelerates rebar corrosion.
+
+## Source
+
+**Citation:** Falcone, J.A., 2023. *Estimates of Road Salt Application across the
+Conterminous United States, 1992–2019 (ver. 2.0, August 2023)*. USGS data release.
+https://doi.org/10.5066/P9MWBBF5
+
+**Downloaded from:** [USGS ScienceBase](https://data.usgs.gov/datacatalog/data/USGS:5b15a50ce4b092d9651e22b9)
+
+## Schema
+
+One row per state (51 rows: 50 states + DC).
+
+| Column | Type | Description |
+|--------|------|-------------|
+| `state_code` | str | 2-digit FIPS state code (e.g. `"48"` = TX) |
+| `salt_tier` | int | Tier 1=Heavy, 2=Moderate, 3=Minimal |
+| `salt_proportion` | float | Relative salt use: 0.9 (heavy), 0.4 (moderate), 0.1 (minimal) |
+
+## Tier Classification
+
+| Tier | Proportion | States |
+|------|-----------|--------|
+| 1 — Heavy | 0.9 | CT, DC, DE, IL, IN, MA, MD, ME, MI, MN, NH, NJ, NY, OH, PA, RI, VT, WI, WV |
+| 2 — Moderate | 0.4 | CO, IA, KS, KY, MO, MT, NE, NV, NM, ND, OK, OR, SD, TN, UT, WA, WY |
+| 3 — Minimal | 0.1 | AL, AR, AZ, CA, FL, GA, HI, ID, LA, MS, NC, SC, TX, VA |
+
+## Join Key
+
+Join to NBI bridge data on `state_code` (2-digit FIPS string).
+
+## Known Limitations
+
+- **Static** — does not vary by year. Salt use has increased over time but the tier
+  classification reflects the long-term average pattern (1992–2019).
+- **State-level** — does not capture within-state variation (e.g., mountain counties
+  in CO use more salt than desert counties).
+- The full USGS release includes annual raster grids at ~1 km resolution for 1992–2019
+  (~230 MB). This simplified tier table is used here as a lightweight proxy.
+
+## Related Datasets
+
+This dataset is part of the bridgedeck collection:
+
+| Repo | Description |
+|------|-------------|
+| `sweetapricity/bridgedeck-nbi` | National Bridge Inventory — structural features, 2000–2023 |
+| `sweetapricity/bridgedeck-prism` | PRISM climate features at bridge locations, 2000–2023 |
+| `sweetapricity/bridgedeck-noaa` | NOAA storm event counts by county, 2000–2023 |
+| `sweetapricity/bridgedeck-nshm` | USGS seismic hazard at bridge locations (static) |
+| `sweetapricity/bridgedeck-nfhl` | FEMA flood zone classification at bridge locations (static) |
+| `sweetapricity/bridgedeck-salt` | **This dataset** — USGS road salt tiers by state (static) |
+
+## Paper
+
+> Ibrahim, A., Abdelkhalek, S., Zayed, T., Qureshi, A. H., & Mohammed Abdelkader, E.
+> (2024). A comprehensive review of the key deterioration factors of concrete bridge
+> decks. *Buildings*, 14(11), 3425.