If you are anything like me, you can’t resist the opportunity to snap a photo of a new or unusual traffic control device while you’re on vacation. I recently had the privilege of spending a week of vacation in Madrid. There I was, in between visiting the Prado Art Museum and eating tapas, filming a Spanish traffic signal. One signal caught my eye because, instead of a single green pedestrian walk indication, there were two green pedestrian figures with linked hands. I was further intrigued when I noticed that the conflicting vehicular movement was flashing a yellow ball.

I filmed the whole sequence: from solid green pedestrian (equivalent to our white walking pedestrian), to the flashing green pedestrian (equivalent to our flashing don’t walk hand), to the solid red pedestrian (equivalent to our solid don’t walk hand).

I’m sure the other tourists were confused as to why I was filming a traffic light, when—by turning 90 degrees—I could have gotten an excellent shot of the Fountain of Neptune. But as my very tolerant wife knows, “engineers gonna engineer.”

After some research, I learned two things. First, Spain is the only country in the European Union that, controversially, allows a flashing yellow indication to denote that drivers may proceed with caution at an active signal-controlled pedestrian crossing. Second, I learned that in 2017 the mayor of Madrid had several pedestrian signals updated to show two male or two female figures holding hands to celebrate Pride Week.

This all got me thinking about the nature of engineering standards and engineering judgment. While anyone who has been a practicing professional understands the usefulness of standards, I know many of us have also chafed at a standard that didn’t match our personal engineering judgment of a situation.

In my judgement, no one was going to be confused by the inclusion of two figures on the walk indication, or by the use of a female vs male figure, but you can decide for yourself. Further, I suspect that including a variety of pedestrian displays in a tourist area could increase the amount of visual attention that non-local pedestrians give to the signals. 

Conversely, thinking about Spain’s permitted flashing yellow indication into active pedestrian crossings gives me knots in my stomach—but it is allowed under their relevant standards. Further, based on my lived experience as a tourist and my professional engineering judgment, Europe’s use of a flashing (green) “Walk” signal to indicate a pedestrian phase that will soon end is easier to misinterpret (and more likely to fail in an unsafe fashion) than the U.S. style flashing “Don’t Walk” indication.

Later that evening, as I was using an artificial intelligence (AI)–powered feature of my smartphone to remove extraneous people from my vacation photos, I continued to ponder the nature of engineering judgment.

I know that many people have mixed and complex feelings about AI. Personally, I am excited about AI’s capacity to reduce the mundane aspects of our jobs, allowing us to focus on the more meaningful, higher-level, judgment-based tasks. In the past couple of years, I have often said, “A calculator used to be a guy in a room with a stack of logarithm tables. No one is sad that job was replaced by computers.” I know, I certainly didn’t feel like pulling out Photoshop to manually edit my pictures.

As knowledge workers, what sets us apart from machines and algorithms is our ability to think new thoughts. A computer can implement the rules and implement them “correctly” (whatever that means) every time. An AI algorithm trained on human-generated data can do an impressive job of impersonating what a human might do (based on what we have done in the past).

What makes an exceptional professional engineer or planner is not the ability to apply standards, but the understanding of why (and in some cases, why not) to apply them. I encourage all of you to think deeply about the standards and best practices you implement regularly. You never know when there might be something better than the standards, something exceptional.

Keep taking photos of traffic control devices! I’m ready to swap photos when I see you at the Annual Meeting this June 29-July 2, 2025.

-Pat Marnell