The Strong Towns Podcast How Traffic Engineering Made America’s Streets Deadly
14 snips
Sep 15, 2025 
Wes Marshall, a civil engineering professor at the University of Colorado Denver and author of “Killed by a Traffic Engineer,” dives into the perilous state of America's streets. He critiques outdated traffic engineering practices and shares personal anecdotes revealing the disconnect between urban and rural infrastructure. The conversation includes fresh perspectives on speed limits and the inefficacy of current safety metrics, while advocating for designs that prioritize cyclist and pedestrian safety. Marshall emphasizes the need for a paradigm shift in urban planning to truly enhance safety.
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Discipline, Not Malice, Drove Harmful Design
- Wes Marshall argues the profession taught unsafe practices as if they were settled science despite weak evidence.
- He blames the discipline's codification of tentative practices, not individual malice.
Codified Experimentation Became Dogma
- Early traffic practices were experimental but later generations treated them as fixed rules.
- That false certainty made harmful conventions hard to change.
Use 85th Percentile To Test Streets
- Use the 85th percentile to test street design, not to set speed limits.
- If measured speeds exceed targets, redesign the street to achieve the target.
