As reported earlier this week by the Center of the American Experiment, motorists face a new 20 mph speed limit in Minneapolis and St. Paul. City authorities figure on a significant reduction in neighborhood traffic fatalities, based on the statistic that a person hit at 35 mph is three times as likely to die as someone hit at 25 mph (they are reducing limits another 5 mph to 20 mph out of an abundance of caution, presumably). Prior to a new law that came into effect a year ago, the Minnesota Department of Transportation (MnDOT) set speed limits based on engineering and traffic studies. But now cities need not involve MnDOT when setting traffic laws for residential streets.*

The lowering of speed limits in the Twin Cities follows a trend in USA metro areas from coast to coast as evidenced by this Seattle Department of Transportation post last December (check out the animated graphic showing how a person’s chance of surviving being hit by a car decreases drastically with faster speeds).

My thoughts:

• If 20 mph on residential streets got enforced, that would be a relief for those like me with young children at home (grandchildren in my case). However, I doubt this will happen, especially with cutbacks in police after the troubles in Minneapolis earlier this year. The lower limits will only work with plentiful speed bumps (more appropriately known as “sleeping policemen” in UK).
• Being an engineer, I worry about taking experts on traffic safety out of the loop in favor of politicians making sweeping edicts with no regard for varying factors for individual streets.
• What are the economic trade-offs of the added time needed to travel at slower speeds versus the increased safety? Is 20 mph optimal?

“Typically, drivers travel 8 to 10 mph above the posted speed limit with a perception that the posted speed limit is a minimum, not a maximum [and] when the posted speed limit is reduced, drivers do not obey the new limit or even pay attention to it unless there is significant enforcement.”

Research Brief: Review of Current Practices for Setting Posted Speed Limits, April 2019, AAA Foundation for Traffic Safety.

One thing for sure, I find it excruciating to drive at 20 mph for any distance. The seems to slow to me.

*Focus on New Laws: Cities Authorized to Set Certain Speed Limits, July 22, 2019, League of Minnesota Cities.