Building-risk ontology from NYC open data
Which Manhattan buildings should an inspector visit first, and why?
NYC publishes building data from several agencies (DOB, HPD, DCP), and each keys it
differently. This project links eight of those datasets into one ontology of landlords,
owners, lots, buildings and events. It scores every lot's risk with an explainable model, backtests that
score on a year it never saw, and puts the result in front of a planner as a map, a building
page and a work queue whose actions are written back.
| |
|---|
| Data | 1.28M events from 8 NYC Open Data sources, Manhattan, 2020 onward |
| Entity resolution | 95–99.7% of records matched to a tax lot (BBL), 89–100% to a building (BIN) |
| Ontology | LandlordPortfolio / ManagingAgent / Owner → Lot → Building → Event, plus RiskAssessment and InspectionTask (writeback) |
| Landlords | HPD registrations link single-building LLCs to the people behind them: 27.8k lots in 13k portfolios (largest: 234 lots) |
| Backtest (2024, unseen) | Top 100 lots: 91% had 10+ new class C housing violations (25× the base rate); 32% had a serious hazard (20×) |
| App | Risk map, building 360, inspector queue with create / assign / record-outcome actions. Streamlit locally; live browser version on Vercel |
Live tool: nyc-building-risk.vercel.app/app ·
Project page: nyc-building-risk.vercel.app ·
Write-up: docs/writeup.md · Backtest: reports/backtest.md
How it works
flowchart LR
subgraph Sources [NYC Open Data]
P[PLUTO] --- F[Footprints]
D[DOB violations] --- C[DOB complaints]
H[HPD violations] --- S[Facade filings]
G[HPD registrations] --- K[Registration contacts]
end
Sources -->|download.sh| R[(raw CSVs)]
R -->|build_db.py: clean + resolve to BIN/BBL| DB[(DuckDB)]
DB -->|build_ontology.py| O[Ontology: objects, links,<br/>point-in-time features]
O -->|score.py: fit 2023, test 2024| RA[RiskAssessment]
RA --> APP[Streamlit app]
APP -->|actions| T[(InspectionTask)]
- Download (scripts/download.sh): Socrata API pulls, filtered to
Manhattan and 2020 onward.
- Resolve (scripts/build_db.py): every record gets a BIN and a
BBL. It tries the record's BIN first, then its block/lot, then condo unit lot → billing lot.
Placeholder BINs (
1000000) and junk dates are handled. The result is reported per source
in match_report.
- Ontology (ontology/ontology.yaml,
scripts/build_ontology.py): object types, link types, actions,
and
lot_features_at(date), a table macro that counts only events before the date. One
query therefore produces both backtest features and today's features, with nothing from the
future leaking in.
- Landlord portfolios: two registered lots belong to the same landlord when their HPD
registrations share a head officer, individual or joint owner, or a corporate-owner name
(connected components).
- Managing agents are a separate object and aren't used for linking: one management
company runs buildings for many unrelated owners.
- Score (scripts/score.py): one logistic regression per outcome over
0–1 components (open class C, facade status, open DOB violations, the landlord's record,
…). The coefficients are the weights, so every score lists its top drivers in plain words.
Which components each outcome uses is decided on a validation year (fit 2022 → validate
2023), before the 2024 test is run once.
- Operate (app/): planners pick lots from the ranked queue, create tasks, assign
inspectors and record outcomes. Tasks live in a separate database, so rebuilding the data
never loses them.
erDiagram
LANDLORD_PORTFOLIO ||--o{ LOT : controls
MANAGING_AGENT ||--o{ LOT : manages
OWNER ||--o{ LOT : owns
LOT ||--o{ BUILDING : has
LOT ||--o{ EVENT : "violations, complaints, filings"
BUILDING ||--o{ EVENT : at
LOT ||--o{ RISK_ASSESSMENT : scored
RISK_ASSESSMENT ||--o{ INSPECTION_TASK : creates
Results
Lots were scored as of 2024-01-01 using only earlier events and compared with what happened
in 2024. Learned models were fit on 2023.
| Outcome (base rate) | v3 (this score) | v2 | Gradient boosting | Naive "same as last year" | Hand-weighted v1 |
|---|
| Housing distress: 10+ new class C (3.6%) | 91% · AP 0.572 | 92% · 0.563 | 91% · 0.570 | 92% · 0.510 | 59% · 0.367 |
| Serious hazard: DOB hazard or UNSAFE facade (1.6%) | 32% · AP 0.146 | 34% · 0.143 | 41% · 0.208 | 50% · 0.138 | 21% · 0.063 |
The table shows precision in the top 100 and average precision (AP) over the full ranking.
Three findings worth stating plainly:
- The hand-set weights lost to simple baselines. Blending two different risks into one
score diluted both. Fitting one model per outcome fixed it, and the result is still
explainable.
- The landlord's track record helps predict housing distress. It was chosen on the
validation year and confirmed on 2024: average precision rose from 0.563 to 0.572, now level
with gradient boosting.
- For hazards, a naive repeat-offender rule still wins in the top 100. Repeat-offender
components looked like a big gain on the validation year (23% → 35%) but didn't carry over
to 2024 (34% → 32%). With about 660 hazard lots, top-100 precision has roughly ±5 points of
noise. I didn't tune further against the test year.
Screenshots
Building 360: score, drivers, event timeline, lot facts, who controls it (landlord
portfolio with their other buildings' scores, managing agent), create task.
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