Are traffic engineering decisions based on evidence-based research? Not as much as you might think.If you’ve seen a car crash on the side of the road, you might look at it and think that the person at fault is the driver. But how much blame should be shared by the people who designed those roads in the first place?Well, some traffic engineers are calling for the field to accept more blame for the crashes and the tens of thousands of annual fatalities that happen on our roads, including Dr. Wes Marshall, a professor of civil engineering at the University of Colorado Denver. In his book Killed By A Traffic Engineer: Shattering the Delusion that Science Underlies our Transportation System, he digs into the standards that have dictated traffic design for decades to find out exactly how much science they’re based on. Spoiler alert: It’s a lot less than you’d think.Host Flora Lichtman sits down with Dr. Marshall to talk about how we got to this point and what a safer version of our streets could look like.Transcript for this segment will be available after the show airs on sciencefriday.com. Subscribe to this podcast. Plus, to stay updated on all things science, sign up for Science Friday's newsletters.