Sidewalk shade index for heat-wave routing
Score every sidewalk segment in a city by tree canopy and building shadow across the day, then feed it to maps apps so July walking directions prefer shaded routes. Heat deaths concentrate among people who walk at midday because they have no choice.
Topics: climate, urban-heat, gis, public-health
The problem
Extreme-heat days are rising and the burden lands on transit riders and outdoor workers who cross unshaded arterials at noon. Cities plant trees by complaint volume, not by where pedestrians actually overheat, and no routing engine knows shade exists.
Who it's for
First: city sustainability offices that need to justify tree-planting budgets with pedestrian exposure data. Second: maps platforms that want a differentiated 'comfort routing' feature. The end beneficiary is anyone walking at 1pm in August.
How it works
LiDAR canopy data plus building-footprint shadow casting gives a shade score per sidewalk segment per hour. Publish it as an open tile layer with a scoring API, pilot with one sunbelt city, and hand OSM-based routers a ready-made weight.
What exists already
Tree-equity maps exist (American Forests) but score neighborhoods, not sidewalk segments, and nothing connects to routing. UNSW's shade-mapping research proved the method; nobody has shipped it as infrastructure other cities can adopt.
Smallest real test
Take Phoenix's open LiDAR and building footprints, score one square mile around a light-rail stop, and walk it with a thermal camera on a 100°F day to validate that scored shade matches felt shade.