Why ants don’t get into traffic jams

Even if you practice alternative commuting by carpool, vanpool, or telework part of the week, you inevitably drive or sit in congestion for a significant amount of time.  When trying to deal with traffic, everyone wonders what lane is fastest and what is causing problems.  In the book Traffic: Why we drive the way we do (and what it says about us), Tom Vanderbilt explains what contributes to traffic problems, how our individual driving habits add to the problem, and best practices for drivers to follow.  Some of his findings, if embraced by drivers, will help clear traffic and keep things running smoother.  Here is a sample of everyday questions:

What causes traffic?
The easiest way to think about traffic is to imagine rice flowing through a funnel.  Like cars, pieces of rice are objects that act in unpredictable ways (unlike water).  If you pour rice into a funnel, the amount of the rice (cars) exceeds the capacity of the funnel opening (roads).  The rice gets denser, runs into other pieces trying to advance through the funnel and gets stuck- just like cars on the road get closer together (and sometimes collide).

Even when there doesn’t appear to be any problems, traffic can seem to come to a stop on its own and then clear up for no reason.  But there actually is a reason.  Traffic jams often act like waves.  When one car stops or significantly slows down, it requires the other cars behind it to all do the same.  Like a spring, the back end must wait for the front end to move again before it can.  When the front does move, each section must have some space to move before the very end, which must wait a significant time to move.  This is what happens with traffic jams you do not see.  Even after the front is moving again, it can be a long time before the back is able to do so.

Are late mergers cheaters?
Picture a three lane highway with a work zone.  You are in the far left lane and there is a large warning sign stating that your lane is closed ahead and traffic must merge right.  A “queue” forms in the lane and there is significant back up in the middle lane (where you will be merging).  At this point, people usually fall into two camps: 1) the early mergers- where people think that it is proper and polite to merge over at the first sign of needing to do so; and 2) late mergers- who stay in their lane until it actually ends and are forced to move over.  Early mergers view late mergers as “cheaters” that are trying to get ahead of all the drivers that “played by the rules.”  However, late merging actually leads to less traffic congestion.  

The problem with early merging is that it creates a number of disruption points where traffic is entering.  Vehicles do not follow a natural flow and create a series of small traffic jams that add up to a larger problem.  Late merging compresses hundreds of merge maneuvers into one single point- sort of like a zipper.  It maximizes use in both lanes, reduces the chance of collisions, and is less stressful to drivers.  In fact, studies show that when areas require late merging, there is a 15% improvement in traffic flow.  The lesson is clear: if you see that you have to merge, just stay in the lane you are in all the way to the merge point and take your turn.

So why don’t ants in a colony- with so many merging and going to various locations – get into traffic jams like people?  The answer, with many others, is answered in the book.  It is an entertaining read that everyone can relate to.  Pick it up and find out how your driving habits can help traffic for everyone!


This entry was posted on Monday, April 26th, 2010 at 1:35 pm and is filed under Uncategorized. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.

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