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.
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.
As with anything related to reducing climate change, if everybody else did it then things would get better and you wouldn’t have to change your lifestyle at all to benefit. But it only needs a few people to not cooperate and the whole system breaks down.
This is a good example of the prisoner’s dilemma, the famous game theory problem. If everybody cooperated then the system as a whole would be much better, but the best thing for an individual when everyone else is cooperating is to be uncooperative and reap the rewards of everybody else’s sacrifices.
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 10m gallons of fuel, how much could a whole city or even a whole country save?