How Traffic Engineers Can Finally Tame Stroads

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The side effects of high-speed stroads include induced demand, suburban sprawl, health consequences, greyfield degradation, the segregation of education and housing, greenhouse gas emissions, unnecessary carnage, and unsustainable spending. Why are these negatives overlooked? Partly because they are hard to recognize. It is also hard to compute reasonable estimates for these side effects, even after recognition.

Yes, traffic calming and livable streets address the side effects of speed, but engineers would need a deep exploration of adjacent disciplines to not only see the benefits, but also account for them fairly. Most are still near the beginning of that journey of discovery, so sadly, that usually means the stroad wins.

After all, engineers can prove, to the third decimal, all the negative impacts of speed reduction. Is an extra minute of drive time a good trade for a safer, livable, vibrant community asset? You might think so, but here’s how engineers see it:

  • 30,000 vehicles x 1.3 people/vehicle = 39,000 people, each losing a minute.

  • 39,000 divided by 60 min/hr = 650 lost person-hours per day.

  • 650 x 365 = approximately 240,000 lost person-hours per year.

Translating to something more understandable:

  • 240,000 / 24 / 365 = 27 person-years of lost time annually.

  • Federal value of time = $21/hr (commercial + general estimate for Highway 210).

  • $21 x 240,000 hours = $5,000,000 per year

If 39,000 people each lose a minute, this aggregates to 27 person-years of time lost each year. If we value that lost time at $21 per hour, this 27 person-years translates to $5 million. It’s a stretch to value one-minute increments of time in this manner, but that’s the way it’s been done for decades, and my fellow engineers are sticking to it!

Taking the Red Pill

About 17 years ago, I began awakening from the Matrix—slowly discovering that stroads have more negatives than positives. But the longtime traffic engineer in me still whispers, “These 30,000 trips don’t have anywhere else to go, and in the minds of engineers still in the Matrix, one minute isn’t trivial—it’s $5 million and 27 person-years of time lost per year!” It’s a hard sell to intentionally make 30,000 trips take longer, all for small immediate benefits. Long-term benefits often depend on land use changes, which can take decades to fully materialize from the new paradigm of mixed-use zoning and infrastructure.

Reducing speed is winlose to the engineer. In their minds, when tiny advocacy groups for “community,” or “equity,” or “modal fairness” win, then 30,000 drivers, or the 90% of the public they feel they must defend, lose.

So that’s the challenge: moving from a constant winlose struggle for the upper hand, to winwin within each discipline’s present “Matrix” paradigm. Seventeen years ago, my search for bridges between these two divides began.

Right Sizing Creates Win-Win Bridging Across the Divide 

I finally found some win-win bridging through a process called “right-sizing” while serving as the lead traffic engineer and design strategist for the recently published guidebook on Right-Sizing Transportation Assets. My friend, Chandler Duncan of Metro Analytics, led the project to publish the guidebook. Together, we published a popular 2020 article in Planning Magazine with seven specific strategies. Key among those strategies is to use what I call “place-making alternative intersections,” which can make it possible to “drive slower, but travel faster,” by reducing delay at signalized intersections. 

When I read Marohn’s article last week, I looked at Washington Street, otherwise known as Highway 210, through Brainerd, Minnesota, to see if such alternative intersections might offer a bridge between what the community wants and what engineers want. A strategy with a lot of potential comes from the “Thru-Turn” family of designs.

Thru-Turn Concept for Taming the Stroad

In a Thru-Turn, instead of left-turn arrows at signalized intersections, which consume precious time and often require huge space for “double left” storage lanes, lefts first go through the intersection, make a U-turn, then turn right. Left turn arrows are no longer needed, and the result is less delay. Normally less delay means the trip from A to B will be even faster—happy engineer! But it also creates an opportunity to introduce traffic calming so that cruise speeds drop from say 45 to 30 mph, without making A to B take longer. Are engineers still happy? Sure. While the efficiency gains were not used to make A to B faster, they do make it safer without making it take longer. They like that, too. Win-win! 

This tool is not new: “Michigan Lefts” have been in Michigan and a few isolated locations for decades. But let’s see what happens when they are tweaked to tame this Highway 210 stroad.

Figure 1 shows “loon turns” at each end for trucks, and back-to-back teardrops in the middle for small vehicles:

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