On 16 Dec 2005 07:04:02 GMT, (Timothy J. Lee)
wrote:

>In article >,
>Brent P > wrote:
>>Just like the other night. I was once again at the set of lights where if
>>I don't get on the accelerator when the first one turns green I get
>>nothing but red lights for several lights in a row. I accelerated
>>rapidly, another driver in another lane didn't. I made the next light
>>just as it was going to yellow, he got a red. I then got greens for
>>several lights in a row while he was red light cycles.
>
>I wonder who designed that light timing.

There is a fallacious assumption that many Sloth Coasters make. Not
every traffic signal is controlled solely by a fixed timer. Most
modern traffic signals are equipped with sensors that detect vehicles
at and approaching the intersection. A car on a cross street half a
block away from the intersection (and out of your sight) might trip
the mid-block loop sensor in the pavement and immediately turn your
light yellow. Many intersections, especially major ones, also have
video cameras with a live feed to a taffic control center, where human
operators have the ability to alter the current operating mode of the
signals as well as direct override control over whether lights are
red or green (e.g. to help clear a traffic jam).

In modern traffic sontrol systems, timers are used primarily to limit
the maximum amount of time a particular direction will get the green
during any particular cycle. The logic is something like

while (traffic_detected AND timer < 2 minutes)
{
DisplayGreenLight();
}

Drivers who try to drive as though the control logic were still

while (timer < 2 minutes)
{
DisplayGreenLight();
}

are going to be seriously dissapointed, at least in SoCal. Places like
Chicago still have many, many older signals which are strictly
timer-controlled - which is how Brent can work the timing to his
advantage and hit several green lights in a row. Unfortunately, many
new immigrants to SoCal who comes from places like Chicago fail to
realize that their old tricks no longer work, and these Sloth Coasters
end up doing nothing but clogging the road.