This morning, as Mark and I drove to work (we carpool — there is no need for us to have separate cars when our apartments are barely 300 metres apart), we got caught in traffic (again) at this one particular intersection in Lindora. It doesn’t look like much, and indeed the satellite photo suggests it’s nothing to worry about. (Looks are deceiving. Trust me.)
We hit this intersection every single day (there have been exceptions) with traffic, due to the large number of cars, trucks, people who need to turn (causing much of the chaos), and a hill combined with another intersection about two kilometres away that backs things up.
Every day, it’s a 5-10 minute trip through this intersection. But today, I noticed something: It would be worse if there were a traffic light.
Interestingly enough, even just a few days I still thought that the intersection could use a traffic light. It’s something I’m very familiar with, as are most North Americans. For us, the traffic light represents order, control, and is often a marker of the size of your town — how many places have you been that can boast having only one traffic light?
And we take that control to extremes. For example, in the just Manhattan borough of New York City, there could be as many as 4,000 traffic lights (1000 city blocks times 4 sets of lights per block). If the power goes out in the Big Apple (which has happened a couple of times), traffic snarls almost instantly. This is how we got the term "gridlock".
Why? Because humans became dependent on someone else directing traffic, rather than themselves.
Let’s go back to our little corner in Costa Rica. If you were to sit on a platform high enough off the ground to see the intersection and all the cars, here’s what you’d see:
- Constant string of cars driving north. A volume of ~1,000 per hour.
- Constant string of cars driving south. A volume of ~1,000 per hour.
- 10% of cars driving south need to turn east.
- 80% of cars driving east turn to the north.
- 20% of cars driving east turn to the south.
The remaining 90% of eastbound cars turn north, having to merge into the northbound cars. (I’m ignoring the cars heading north that turn east ‘cuz they really don’t do anything to traffic flow.) It should be noted as well that while the north-south road is technically two lanes with a turning lane, during the morning commute it effectively becomes a 3-lane road (two north, one south) until you reach the intersection. There are no traffic signs north or south. The eastbound road has a stop sign (not that many people pay attention to signs in Costa Rica).
Sounds like a recipe for disaster, right?
You’d think that until you watch it for a while. (Such as in our case — over four months.) Here’s what usually happens…
- Southbound moves usually without stopping (though movement is slow due to other traffic issues further south)
- The two northbound lanes merge into one lane before (sometimes in) the intersection
- The odd car or truck stops to allow a burst of left-turning southbound cars, and south-turning eastbound cars (they go in pulses)
It becomes self-organising. It’s not unlike a traffic flow observation made (somewhat recently; be damned if even Google can’t find the article for me) where someone suggested that vehicular traffic should take a note from computer networking traffic, and merge only when it’s necessary: right at the intersection. In our case, traffic slows (lessening the chance of an accident — we have yet to see one there), people are ready for having to maneouver, and people move on.
After this realisation this morning, I started to think more about the idea of self-organisation rather than hard-line controls. Look to the United Kingdom and Ireland for some great examples. Yes, there are still traffic lights, but there are far fewer of them, and more emphasis on things like traffic circles. Even on major highways, the roads continue to flow well with them. (Traffic circles are used very effectively in Costa Rica as well.)
Europe has embraced this in many countries. I believe Holland was such an example where stop signs were eschewed for traffic circles, wide shoulders, and less paint on the roads. Accidents actually dropped. (Again, I’d love to back this up with an article, but I can’t remember where I saw it.)
Which makes me wonder: How much does North America place artificial controls on traffic patterns that could actually be self-governing with a little bit more planning?