Fifty-four parcels left.
Fourteen pass the first screen.

The ground that ranked them

This is the surface the whole screen runs on, the 2021 MassGIS bare-earth hillshade, showing all fifty-four parcels with the fourteen that passed in green and the forty that did not in brown. Drag the line to compare current aerial imagery against the lidar, and click a parcel, a ranking card or a brown site to stand on that terrain.

AERIAL IMAGERY

2021 LIDAR HILLSHADE

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All 54 screened parcels on 2021 lidar hillshade. Green passed; brown did not.

What one highway is worth screening

This screen covered 20 km of I-495, which runs 195.6 km in Massachusetts, so the studied stretch is about a tenth of the highway. At the rate found here, 54 candidate parcels and 14 that pass, the whole of I-495 would hold on the order of 530 candidates and 140 passing, or roughly one viable site every 1.4 km of corridor.

Treat that as arithmetic rather than a survey. The studied stretch was chosen because it is where industrial development actually happens, and the northern and southern ends of I-495 run through different land use, so the rate almost certainly does not hold evenly along the whole road. The useful part is not the estimate. It is that the screen which produced it ran on free public data, and pointing it at another corridor is a day of work rather than a survey contract.

How the screen works

1. Parcels. MassGIS L3 tax parcels joined to assessor records for the corridor towns. The screen kept parcels of 10 acres or more, classified vacant, forest or developable land, carrying under $50k of building value and lying within 1.5 km of the MassDOT I-495 centerline. The nine towns are Hopkinton, Holliston, Milford, Hopedale, Upton, Mendon, Medway, Bellingham and Franklin.
2. Terrain. The state's 2021 bare-earth lidar DEM, resampled to 1 m. Across Studies 01 to 03 my point-cloud models and the state's DEM, derived from the same flights, differed by 2.0 to 7.6 cm RMSE, which supports processing consistency rather than independent field verification. Wetlands and streams come from DEP layers with 100 ft and 200 ft screening buffers.
3. The pad search. The same optimizer as Study 03, run inside every parcel. Every possible pad position is tested, and the largest pad is kept where at least 70% of the window passes the terrain and mapped-buffer screen and 95% sits inside the parcel.
4. What a screen doesn't do. There are no canopy metrics here, no wetness-discrepancy or rock screens, no access routes and no zoning. Those belong to the per-parcel study, run on whichever of these parcels matters to you. Costs use the same $20/yd³ basis and the same caveats as the other studies.

Scope: a public-data demonstration. "Pass" means passing the stated terrain and mapped-buffer screen, not approved, permitted or confirmed buildable. This does not review current title, ownership, zoning, frontage, legal access, utilities, field wetlands, soils, endangered species, cultural resources, or permitting. A shortlist this small is what makes a deeper study practical for the parcels that matter. Scripts and pipeline files are available on request. Read the full assumptions, sources and limitations.