What is the relationship between vehicle speed and pedestrian survival?

Pedestrian survival rate falls sharply with impact speed. At 30 km/h (19 mph) approximately 90 percent of pedestrians survive a vehicle impact. At 40 km/h about 60 percent survive. At 50 km/h roughly 20 percent survive. At 60 km/h fewer than 10 percent survive. Each 1 km/h increase in impact speed increases fatality risk by approximately 4 to 5 percent. The relationship reflects human biomechanical limits, not driver skill or pedestrian attention.

Why do traffic fatality rates vary so much between countries?

Traffic fatality rates vary by 10 to 15 times across countries. Sweden has 2.0 deaths per 100,000 population, Japan 2.7, Netherlands 3.4. The United States is at 14.2, India at 14.6, Thailand at 25.4, Guinea at 37.4. The variation tracks closely to street design philosophy rather than driver skill, enforcement intensity, or per-capita income. Countries that engineer streets to constrain vehicle speeds in pedestrian areas have low fatality rates; countries that design streets for vehicular throughput have high ones.

How does Vision Zero work?

Vision Zero is the Swedish road safety policy adopted in 1997. It shifts responsibility for traffic safety from individual users to system design. Rather than assuming drivers will obey speed limits, Vision Zero redesigns streets so that compliance with safe speeds becomes the path of least resistance. Sweden reduced its national fatality rate from over 15 per 100,000 to 2.0 per 100,000 through this approach. Vision Zero has been adopted as a stated policy by dozens of US cities, with mixed implementation.

What design parameters reduce pedestrian fatalities?

Five design parameters consistently correlate with reduced pedestrian fatalities: (1) narrow travel lanes (2.5 to 3.0 meters) that constrain operating speeds without speed limit signs; (2) physical separation of pedestrians, cyclists, and vehicles; (3) frequent crossing opportunities at 80 to 100 meter intervals; (4) pedestrian refuge islands enabling two-stage crossings; (5) continuous protected sidewalks. These principles are implemented in cities worldwide and produce consistent results.

Why do American streets produce so many pedestrian deaths?

The American street network is dominated by arterials, four to six lane commercial streets engineered for 50 to 70 km/h vehicle throughput in places where pedestrians need to cross. The same drivers, given a Dutch road network, would produce Dutch fatality rates. The fatality rate gap (14.2 per 100,000 in the US vs 2.0 in Sweden) reflects design philosophy, not driver behavior.

Street Design Determines Survival: The Math Is Clear

Pedestrian survival probability falls from 90% at 30 km/h to under 10% at 60 km/h. Street design determines vehicle speeds, and vehicle speeds determine survival. A look at the data behind Vision Zero, Sustainable Safety, and the 10-15x variation in road fatality rates between countries.

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