Diminishing Returns of Speed
I picked up a Harvard Business Review recently and read an article called Linear Thinking in a Nonlinear World (10/10 would read again). Logic of the articles says we naively project ideas linearly, yet there is either diminishing returns or exponential returns we miss from not thinking deeper about the topic. This got me thinking about speed or “miles per hour”. Speed, as a function of time, has a non-linear return on value. Below is a chart of the number of seconds gained for each additional MPH a driver averages over 5 miles:
Marginal returns from 0 to 10 MPH are extraordinary, thus, the highest value for traveling is simply continuing to move. The highest marginal values of traveling are within range that is achievable by a bicycle.
Since 0 to 10 skew the chart, let’s only chart values above 10 mph:
What this chart says is that by going 12 mph instead of 11mph over 5 miles, the traveler saves 163 seconds. And, by traveling at 41mph instead of 40mph over 5 miles, the traveler gains 10 seconds.
Actual times instead of marginal times
The actual time it takes to travel has a similar curve:
How does this affect drivers decisions?
Every driver is answering the same economic question about time as they drive: how can I get where I’m going faster? Thus, each morning commute is an run of a testing scenario for each drivers’ behavioral economic decision.
The non-linear return on speed encourages bad behaviors:
- aggressive driving to get through traffic-lights — the only value of a traffic light for an individual driver is to be past it
- short cuts through neighborhoods to keep moving — getting around slow spots by going incrementally faster
- driving aggressively past slower moving pedestrian or bicycle traffic
Anything that causes a driver to drop below their perceived marginal value for driving causes them haste and rush and hurry and aggression.
How should roads & neighborhoods be designed?
Travelers moving on the faster end of the spectrum (the low marginal return) detract from the value of travelers moving on the slow end (the higher marginal return). This value detraction means that pedestrians don’t use roads and kids and elderly don’t ride bicycles — you have to be an athlete to participate as a pedestrian on a road with aggressive drivers.
Thus, fast roads should be fast and slow roads should be slow. Drivers trying to use slow roads to be fast should be punished by taking additional time from them —imagine a police officer telling the person “I’m not going to write you a ticket, but I’m going to make you sit in timeout” — recognition of the loss of time would be as punishing than a ticket.
Other ways to do this is with:
- clearly delineate with signs and change of road width when a driver moves from a high speed road to a slow speed road
- remove or dead end non-essential connections between fast roads and slow roads
- on medium speed roads, use roundabouts and good traffic flow to keep drivers in their comfortable marginal value ranges (cars sitting at other wise empty red lights cause more aggressive driving)
Long story short — remove the option of drivers to harvest seconds from your neighborhoods.
