Not all streets feel safe to bike on. This story maps the gap between where cyclists could go and where stress lets them comfortably travel — and shows which streets, if made safer, would make the biggest difference.
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For this study, Northampton was divided into a grid of hexagonal cells, each about 500 feet (150 meters) on a side — roughly the size of a city block. Within each cell, we found the population-weighted center: the point closest to where most residents actually live.
Each circle on this map represents one of those cells, sized and colored by the number of residents. Large red circles are densely populated; small pale dots have fewer residents. These are the starting points for every trip in the analysis.
Seven public schools (shown in red) serve Northampton's children. The daily school commute is one of the most revealing tests of a city's cycling infrastructure: it's a trip families make repeatedly, in all weather, with children in tow.
Whether neighborhoods can reach their schools by bike — comfortably, not just theoretically — shapes whether families ever try.
Beyond schools, people travel to libraries, the YMCA, grocery stores, parks, downtown shops, and medical facilities (shown in green). These are the places a connected cycling network should reliably reach.
Together, schools and other destinations give us roughly 9,000 origin-destination pairs — one for every population cell and destination combination.
If cyclists could ignore traffic stress entirely and always take the shortest route, this is where bicycle traffic would concentrate. Bright red lines carry the most riders; pale lines carry fewer.
Routes spread across the full network — including high-speed and high-traffic roads that many cyclists do not feel safe using.
Now we penalize high-stress streets, routing cyclists onto calmer alternatives even when they're longer. The network shifts: some streets gain traffic as low-stress alternatives, while high-stress roads lose riders.
Blue lines show where cyclists actually want to go when the route respects their comfort. The thickest corridors are Northampton's true cycling backbone.
Even when routing avoids stress, some high-stress streets remain. These red segments still carry significant bicycle traffic in the comfort-aware scenario — they're simply unavoidable.
Often these are bridge crossings, key intersections, or connector streets with no parallel alternative. Improving just a handful of these segments could unlock much safer routes for thousands of trips.
Combining both signals: streets that cyclists actively detour around (they were used on shortest routes but dropped when comfort mattered) and streets that remain unavoidable despite their stress. The score reflects the magnitude of avoidance or unavoidable use.
These are Northampton's most critical cycling infrastructure needs — the places where investment would have the largest effect on ridership.
Every street in Northampton has been rated for Level of Traffic Stress (LTS) — a measure of how safe and comfortable it feels to bike. LTS 1 streets are comfortable for almost anyone, including children and seniors. LTS 4 streets are high-speed or high-traffic roads suitable only for the most experienced riders.
Using residential address data, we overlaid a grid of hexagonal cells — each about 500 feet (150 meters) on a side — on Northampton and found the population-weighted center of each occupied cell. We then identified seven public schools and dozens of everyday destinations across the city.
For each of the origin-destination pairs, we calculated two routes:
By comparing these routes, we can see which streets carry the most bicycle traffic, which streets people go out of their way to avoid, and which streets — if made safer — would collectively save cyclists the most extra distance.
Analysis and mapping: Kent S Johnson.
Level of Traffic Stress criteria: Peter Furth, Northeastern University.
Data: OpenStreetMap street network · municipal address data · school district boundaries.
Analysis: R / flownet package.