Inputs & assumptions
Every shelter is modeled from its actual JCDecaux model — roof area, and so retention, cooling, and stepping-stone area, follow from each shelter’s real canopy and whether it carries solar panels. Cooling and cost values below are provisional, to be updated as the Brownsville pilot is monitored and agency-aligned coefficients land via SOW Task 2.
| Model & available canopy | Per-shelter, from the DOT inventory: a 4-section canopy is 14 ft, a 2-section (short) canopy is 10 ft; a regular footprint is 5 ft deep, a narrow one 3 ft 6 in — gross roof ≈ 35–70 sq ft. Solar (“AD Solar”) models carry a roof-mounted PV array powering the illuminated ad panel; absent a published JCDecaux spec we assume it occupies ~50% of the canopy, so available green-roof area is ~half (a shelter with no usable roof is flagged out of scope). Digital models keep a full roof (screens sit on the ad panel, not the roof). |
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| Green-roof coverage | Adjustable, default 100% of available canopy. Scales the green-roof area, and so retention & cooling, linearly with coverage. |
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| Substrate depth | 4 in extensive green roof media (porosity 0.30) over a 2 in drainage/retention layer (porosity 0.25) — shallow, lightweight, sedum-forward; not an intensive/deep-soil roof. Method: CNT Green Values. |
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| Plant palette | Sedum-forward, NY-appropriate, low-maintenance |
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| Retention (per storm) | ≈0.62 gal / sq ft / 1″ storm at 100% coverage (≈44 gal on a full 70 ft² roof, scaling down with available area). Derived from the CNT Green Values green-roof storage method: storage depth = 4″×0.30 + 2″×0.25 = 1.7″; a 1″ storm is fully retained (rain-limited, storage 1.7″ > 1″), larger storms cap at the 1.7″ storage. |
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| Retention (annual) | ≈49% of rainfall (≈1,070 gal/yr on a full 70 ft² roof, scaling with available area). Built from NYC’s measured daily rainfall (NOAA GHCN-Daily, Central Park, 1991–2020 normals — 49.5 in/yr) run through a daily green-roof water balance: rain fills the 1.7″ storage, excess runs off, and the roof dries between storms via seasonal evapotranspiration (FAO-56 Hargreaves reference ET). Calibrated to the ~50% reported for temperate extensive roofs (Mentens et al. 2006; NYC monitoring, Carson et al. 2013); the dominant uncertainty. |
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| Cooling effect PROVISIONAL | Reported as an under-shelter heat-stress reduction, split into two cited parts: sheltering ≈4°F (a stainless-steel frame with glass roof — the NYC shelter type — gave the largest heat-stress reduction of four designs tested, Yang et al. 2024); the green roof adds ≈2°F on a full 70 ft² roof (extensive green roofs cool near-surface/pedestrian air ~0.4–1.3°F, with a larger radiant effect directly beneath a low canopy; Wang et al. 2025), scaling with available area & coverage. Both are provisional pending Columbia pilot measurement. |
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| Retrofit cost ROM | $1,400 – $7,000 per shelter (rough order of magnitude). Structural + waterproofing + media; dominated by fixed structural/labor cost rather than roof area. To be refined with the team. |
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Agency lineage
Where possible, lenses align with frameworks already in use at NYC agencies, to avoid duplicate measurement burden and to slot into existing decision-making processes (NPCC standardization work, OMB capital-project intake).
| Heat | NYC CEJ heat metrics (Helen Cooper). Community framing reports the share of in-scope stops in high-HVI areas (NYC DOHMH Heat Vulnerability Index ≥ 4), alongside the pedestrian demand of the served streets (NYC DOT Pedestrian Mobility Plan — nearest-segment category, most-common across a scope). Replaces the earlier route-summed ridership proxy, which was not a reliable stop-level signal. |
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| Stormwater | Per-storm retention from the CNT Green Values Calculator green-roof storage method (substrate + drainage water-holding volume); annual retention from NYC’s measured rainfall (NOAA Central Park) via a daily green-roof water balance with evapotranspiration. Community framing reports the share of in-scope stops in high flood-burden areas (NYC MOCEJ FSHRI ≥ 4). Aligns with NYC MOUA conservation metrics (NY State Soil & Water District) + NYC DEP Green Acres standards. |
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| Biodiversity LOW CONF. | Pollinator habitat connectivity, as a gap-crossing stepping-stone score per shelter (landscape-connectivity method — Saura & Pascual-Hortal 2007; anchored to solitary-bee foraging ~250–300 m — Gathmann & Tscharntke 2002). A siting heuristic, not a measured benefit: green-roof-as-habitat evidence is weak and a shelter roof may be below the effective stepping-stone threshold. Patches = NYC parks (DPR) + MOUA urban-agriculture sites + DEP green infrastructure (plant-bearing only — concrete-top infiltration basins excluded) + 2015 street-tree census (alive). Because street trees are dense, most stops can now bridge some green, so the score reads as a relative gradient (green roofs add most where surrounding green is sparse). On the map the lens shows the green spaces within ~300 m of a stop; in Single-shelter scope, arcs link the selected stop to its nearest reachable patches and street trees. |
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| Air quality | Foregone in this evaluation phase — shelter-scale sensors are physically too large and approval timelines do not fit the current pilot window. |
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What each lens reports
- Heat — the under-shelter heat-stress reduction (sheltering + green roof), the share of in-scope stops in high-HVI areas, and pedestrian demand.
- Stormwater — per-shelter retention per 1″ storm, total retention across the scenario, and the share of in-scope stops in high flood-burden areas.
- Biodiversity — the connectivity score, how many shelters act as stepping stones, and what each bridges (tree, park, garden, GI).
Per-shelter figures (cooling, retention) are non-additive across shelters, so multi-shelter scopes report a representative value; totals are shown only where they genuinely sum (retention gallons).
Scope
- All sheltered stops are eligible. The scenario operates on every existing bus-shelter stop (≤25 m shelter–stop match); the viable-typology gate has been removed. Stops with no shelter are shown for context (binary sheltered/unsheltered) but excluded from the scenario.
- Structural capacity — which JCDecaux typologies can carry a green-roof load is still to be confirmed with the team; for now all sheltered stops are modifiable.
- Single-shelter scope defaults to the Brownsville pilot stop (Pitkin Av & Saratoga Av); click any shelter on the map to switch.
- Borough scope aggregates shelters by borough. Finer-grained NTA / Climate Strong Communities geographies are future work.
Open work
- Biodiversity lens — pending Columbia measurement capacity + partner institution coordination.
- NTA & Climate Strong Communities geographies for a finer-than-borough scope.
- Formal DEP "green acres" translation for stormwater community-scale row.
- OMB capital-project key indicators + Technical Appendix B alignment.
- Helen (CEJ) & Kiana (MOUA) metric-table integration once permission to share is confirmed.
- Designed PDF tear sheet (currently uses browser print stylesheet).
Data sources
- Bus routes / stops: MTA
- Bus shelters (model, canopy, solar): NYC DOT (JCDecaux inventory)
- Pedestrian demand: NYC DOT Pedestrian Mobility Plan — Pedestrian Demand (nearest-segment category)
- Heat Vulnerability Index (HVI): NYC DOHMH 2024 (by MODZCTA)
- Flood Vulnerability (FSHRI): NYC MOCEJ 2024 (by census tract)
- Biodiversity patches: NYC DPR parks; NYC MOUA urban-agriculture sites; NYC DEP green infrastructure; NYC 2015 Street Tree Census
- Green-roof stormwater retention: CNT Green Values Calculator methodology (per-storm storage volume)
- Rainfall (annual retention model): NOAA NCEI GHCN-Daily, NY City Central Park (USW00094728), 1991–2020 normals
- Cooling: Yang et al. 2024 (bus-shelter thermal study); green-roof pedestrian cooling (Wang et al. 2025) — provisional