I often bike from my home south of downtown St. Paul to my mother’s apartment at Lexington Parkway and Randolph Avenue. The trip requires travelling on the Sneaky Trail (named and described by Dana Demaster in a 2015 post, Lesser of Three Evils for my Saint Paul Bike Commute). While she has concerns about the trail’s beginning and end points, I get nervous at the corner of Grace and Osceola.
Heading west on Grace, I have a stop sign; but the traffic heading south on Osceola leads to an intersection at the end of a broad curve that has no stop sign. I always ride across that intersection nervous about cars that may be speeding on the empty, unimpeded stretch, and my inability to see them before I am in the middle of the intersection.
So I called the city’s Public Works department to learn the process for requesting a stop sign for southbound Osceola. The answer: a stop sign is not an option for that intersection because … it is unlikely drivers will see the stop sign in time to stop.
About the time I made these calls I bought the book “Killed by a Traffic Engineer: Shattering the Delusion that Science Underlies Our Transportation System” by Wes Marshall (2024). Streets.mn readers — both the experts and those of us who come to the site to learn — will find this book useful and interesting. It lays out multiple features of the systems behind traffic engineering that lead to the danger in our current roads.
As a professor of civil engineering at the University of Colorado, Denver, Mitchell has deep expertise, and it shows. The delight is he does not write like an engineer: He writes with wit and humanity. The 372-page book is divided into chapters that are usually three to six pages long. The sources of his footnotes are as likely to be the Simpsons and David Bryne as they are to be from the Traffic Quarterly (later Transportation Quarterly newsletters published by the Eno Foundation from 1947 to 1981). He tells you the names, ages and life details of people killed while walking alongside or crossing streets. He expresses indignation about bad science.
I learned, for instance:
- How the fact that federal funds would only pay for highways coupled with “slum clearance” goals inspired planners in the 1950s to envision freeways through the middle of cities. (Which explains the most compelling reason MnDOT might not have favored transforming I-94 between St. Paul and Minneapolis into a boulevard: lost opportunity for federal funding.)
- Why Vision Zero programs to end traffic deaths and injuries have not succeeded in most places.
- How bike paths can be considered “a clear zone” for out-of-control cars and trucks needing to recover their bearings.
I learned I am up against the “Manual on Uniform Traffic Control Devices” in my concerns for the intersection of Grace and Osceola. Unlike most of the traffic engineering “manuals” that he notes are “more what you’d call guidelines,” this one contains “the rules surrounding traffic signs, signals and markings … something close to [actual] standards.”
He does not single out engineers as individuals for ridicule or scorn. Instead, he outlines what he thinks are failures in the categories created for roads, the guidelines in the manuals, the faulty science behind the engineering standards in those manuals and the way traffic engineering is taught.
His examples are tangible and useful. Did you know:
- That the formula used to determine how steep a curve should be banked is based on a 1935 study in which “several hundred” drivers were asked to drive through curves of different pitches and then “to report the speed at which they felt the car begin to ‘pitch outward’?”
- Or that a survey in the early 2000s of all post-secondary transportation engineering programs reported that 29 out of 117 had a course in safety. Only four had a second safety course. (The University of Minnesota has a graduate program in Transportation Engineering. I find no titles online that indicate safety being the primary focus of any course, unless “Theory of Traffic Flow” would count.)
Marshall also offers solutions:
- Instead of making streets safer by fixing a never-ending series of hot spots, look at community-wide safety for specific populations, such as children, older adults or those with disabilities.
- Instead of designing roads from the center line out, design them from the outside edges in. Start with sidewalks, bicycle lanes and transit lanes. Make safety-impact analyses required in roadway designs. Update the science in traffic manuals. Focus safety efforts on engineering more than education and enforcement.
- And most importantly: Analyze fatalities and injuries as systemic problems, not as individual human errors.
For me, I learned that the “Manual on Uniform Traffic Control Devices” mentions professional engineering judgment 167 times — opening the door to discretion. That could mean considering that if people in cars cannot see stop signs in time to stop, can they see people on bikes in time to avoid hitting them? And if not, is there some room to consider whether there are ways to make an intersection safer?