Let's Outlaw Left Turns!

Thursday, February 09, 2017

Until I found a navigation app that didn't annoy me (Waze, which is actually fun to use), I hated driving in DC. One of the many reasons is that, ironically (given who had been there for the past eight years), left turns are often prohibited.

Leave it up to a leftist to show me what irony really is...

You wouldn't expect an idiotic proposal from the title or beginning of this Quartz article, but it eventually happens. The article starts off innocently enough with a technique for saving fuel (and vehicle wear) you may have heard that UPS uses:

It might seem strange, but UPS delivery vans don't always take the shortest route between stops. The company gives each driver a specific route to follow and that includes a policy that drivers should never turn through oncoming traffic (that's left in countries where they drive on the right and vice versa) unless absolutely necessary. This means that routes are sometimes longer than they have to be. So, why do they do it?

Every day, along with thousands of other companies, UPS solves versions of the vehicle routing problem. In these mathematical problems, you are given a set of points and the distances between them, and you have to find the best route(s) to travel through all of them. "Best" is usually defined as the route with the shortest overall distance. [link in original]
Yes. It is usually "best" to pick the shortest linear distance possible when selecting a route, because it usually saves time. But, as the article (and, often, Waze) indicates, other factors can come into play. An accident or heavy traffic ahead might make a route that is twice as long the fastest one between two of the points, making it "best" for that step, even if another order is considered. And, yes, fuel economy can come into play.

And actually, come to think of it, the general purpose of the trip can affect what route is "best." I like to lump numerous errands together to save time I'd waste if I'd return home between each stop. If you considered my route to any subset of these in isolation, you might wonder why I selected such a lousy solution, distance-wise. Or, maybe I do groceries last, so as not to thaw frozen items. Lacking knowledge of that "point", my solution might look suboptimal to someone with little knowledge of my purposes. UPS is clearly doing something similar here, only with many more stops, and with a heavier weight than many other drivers might place on saving fuel.

And save fuel they do, as the folks on Mythbusters once proved:
It seems incredible that not turning left can lead to such significant savings. The TV series Mythbusters tested this idea and confirmed that, despite many more turns, the policy of only turning right does save fuel. In their one truck experiment they travelled further, but when you scale this up to a global level, UPS really does travel fewer miles in total. [link omitted]
The distance savings, I am sure, is related to the fact that one route has many pick-ups or deliveries. The fuel savings would be a combination of that and engine time (fuel) not wasted idling at a left turn either waiting on a signal -- or the kind of perfectly-timed traffic I get in Maryland where traffic in one direction picks up just as that in the other ends. (I "turn right to turn left" a lot here, to save time, but this often involves an easier left, and I may or may not save fuel. My goal is to make the time of my route more predictable. Yes, sometimes I lose time doing this, but it beats randomly adding ten minutes to a given trip.) Do note here that my left-turn policy and that of the folks who own and operate UPS are each determined by our personal goals. This is important, because the author, Graham Kendall, doesn't give a damn about your personal goals:
The success of UPS's policy raises the question, why don't we all avoid turning left (or right, depending on what country we're in), as we drive around cities on our daily commutes? If everyone did it, the carbon savings would be huge and there'd probably be far less congestion.

The problem is that not every journey would be made more efficient by following this strategy, and most people are likely only to change their driving style if they personally benefit.


So, if you cannot persuade people to always turn right (or left) for the benefit of everyone, it might be down to governments to encourage or even enforce the strategy. For example, we could plan roads that make it more difficult to turn through the traffic. It would take a brave city planner to implement this, but if UPS can save 10 million gallons of fuel, how much could a whole city or even a whole country save? [link in original, bold added]
Why don't we all avoid left turns? Kendall, who advocates "selfless driving" answers his own question: Because there isn't always a selfish benefit to doing so. And how will you convince people to do something patently ridiculous, given that most people aren't spending hours at a time making deliveries? He knows the answer to that one, too, and it is a sad sign of the times that he isn't too embarrassed to offer it. I strongly suspect that forcing everyone to drive the way Graham Kendall fantasizes they should, might not necessarily achieve his goal, anyway. But that's beside the point, because it is an abuse of government power to order people around, to deprive them of liberty for any reason other than that they have violated (or threatened to violate) the rights of others.

There is truly nothing off-limits to an advocate of unlimited government power like Graham Kendall, as numerous improper federal regulations already attest. My title doesn't precisely describe Kendall's meddlesome proposal, but isn't hyperbole.

-- CAV

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