The 20th century economist F.A. Hayek developed the concept of spontaneous order, which he described as, "that which is the result of human action but not of human design." Taken to the extreme, spontaneous order could imply that humans are entirely capable of organizing and progressing themselves without the existence of individuals or institutions such as the government, which direct society in a certain manner rather than allowing it to direct itself. Spontaneous order exists all around us if we stop for a moment to realize just how astonishingly pervasive it really is. This is precisely why I found it to be of no particular surprise that when traffic lights were installed in the city of Las Cruces, New Mexico, accidents increased by 18 percent. In fact, this type of outcome is the reason why the cities of Drachten in the Netherlands and Bohmte in Germany have decided to remove their traffic signs: to improve road safety.
One way to see this mechanism at work is through a simple thought experiment. Let's envision two main scenarios, each with two sub-scenarios. The two main scenarios are: one scenario in which you are sober and another driver is sober, and the second scenario in which you are sober and another driver is drunk. The two sub-scenarios are: one sub-scenario in which there is a traffic light, and the second sub-scenario in which there is no traffic light.
So what happens if you and another driver, both sober, approach an intersection with a traffic light? Whichever one of you has the red light will stop, and the other driver will continue on his merry way. You are both following the established rule that red light means stop and green light means go. What happens if the same two drivers approach the intersection and there is no traffic light? Both drivers are likely to slow down (out of fear of not knowing who should go first) and through common gestures/courtesy determine who is to go first. In both of these cases, the outcome is similar (there will be no accident) because when both drivers are sober, many accidents can be avoided no matter what the circumstances. So this first set of scenarios does not reveal very much.
Now we can look at the scenarios in which you are sober and the other driver is drunk. If you both approach an intersection in which you have a green light and the other driver has a red light, there is a good chance that as a result of being drunk, the other driver will continue through the red light and crash into you as you go through the intersection. The institutionally imposed rule that red means stop, now means nothing at all. In contrast, if you both approach an intersection (you sober, he drunk) in which there is no traffic light, you are likely to notice that as you approach the intersection, the other driver is not paying any attention to you and/or not slowing down (remember, he is drunk). Common sense would have you slow down and simply let the other driver do as he pleases so you stay out of harm by waiting for him to pass. In these two scenarios we see that at a time when we want traffic lights to function best (when a driver is drunk, careless, daydreaming, etc.), they are likely to function worst.
These scenarios could all be made more complex/nuanced/realistic but the point is that humans spontaneously adapt when having to create their own norms rather than relying on and having those norms created for them by an external person or institution.
As a side note, in the case of two drunk drivers, there isn't necessarily something that can save them based on these simplistic scenarios that I created, but we can at least see that not having traffic lights is superior in the case of one sober driver and one drunk driver. But I am also willing to bet that, though I can't think of a way at the moment, spontaneous order would find a way to safely deal with multiple drunk drivers. That above all is spontaneous order's most impressive characteristic: the ability to create spontaneously and unexpectedly.