Tuesday, March 8, 2011

game theory and the bicycle commuter

My route to work takes me along roads limned with bike lanes, through traffic lights, through intersections where I have the right of way and through 4-way stops where the vehicle who reaches the line first wins!  huzzah!

One of the stranger intersections I encounter is on E. Long Meadow.  It is a four way red traffic light.  It defaults to red when there are no vehicles nearby.

A bicyclist approaching this red light can check their speed, hesitate in their progress fractionally, and then continue on with the sure knowledge that the light will turn green before they are actually in the danger zone of the intersection.

The cars know this too.

The vehicle to reach the intersection first will claim the green light.

Better yet is to be the vehicle to reach the intersection second, in the direction of the winner.  That means you do not need to check your speed.

Worst is to have someone travelling in the other direction first get to the light and trigger it green for themselves leaving you to wait out the red.

The weird result is a kind of hurry up and wait.  If no one is coming from the other direction the cars and bikes heading in the same direction fight to be in the coveted second place where they won't need to slow their ascension towards the holy awesome of high speed and can just hurtle through the intersection confidently.

You don't want to be too far back in the pack though because as soon as no one is going through the light it reverts to red and you have to wait for it to trigger green.  You definitely don't want to be so far back that a car coming from the other direction sneaks up and claims green for itself.

Did I mention this is a weird light?  It is.  And not really a very good one.  It trains everyone who approaches it to speed to be first and it also trains them that it will turn green as they go through it.  If this thing ever turns into an actual normal behaving light there is going to be a spectacular accident.

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