Waiting minutes for a light that never changes
 

On Sun, 8 Nov 2009 09:24:23 -0800 (PST), larry_scholnick wrote:

> Much of the City of Los Angeles has traffic signals where the primary
> street gets a green light forever, until either traffic on the side
> street is detected by the sensor or the pedestrian button is pressed.
>
> This morning while walking I came upon the scene of a woman who had
> stopped at a red light on the side street, but had driven through the
> crosswalk and was stopped beyond the crosswalk. The traffic sensors
> are located in all traffic lanes in the 20 feet preceding the
> crosswalk and halfway through the crosswalk. She had stopped so far
> forward that the traffic signal was completely unaware of her
> presence.
>
> While I was watching, a southbound car on the primary street tripped
> the left turn lane sensors; the traffic signal responded
> appropriately. Northbound traffic cycled to red and the southbound
> left arrow cycled to green. Much to the women's dismay, the traffic
> signal returned to its default state, green for north/south, and
> waiting for sensor input from east/west or from the left turn lane.
> Luckly for her, another car pulled in behind her, stopping legally
> (before the crosswalk) and tripping the sensor.
>
> I considered walking out to explain the situation to her, but I'm not
> sure that I could have avoided being insulting, so I quietly let her
> experience the consequences of her actions.
>
> For those of you who wonder why the traffic sensors did not trip when
> she drove over them (which she certainly must have done), let me
> explain. Many traffic signals in Los Angeles operate on a fixed
> timing sequence. Here's a typical 60-second cycle:
>
> 00 - Check sensors; if car present or pedestrian button has been
> pressed since last sensor check, begin blinking red DontWalk for side
> street.
> 10 - If cycling, solid red DontWalk, and display Yellow light for
> primary street.
> 12- If cycling, display Red light for primary street and Green light
> for minor street.
> The light stays green for the minor street for 20 seconds if the
> pedestrian button was pressed, or until 2 seconds of sensor inactivity
> on the minor street.
> 32 (or earlier) - Display Yellow light for minor street.
> 34 (or earlier) - Display Red light for minor street and Green light
> for primary street.
>
> If you are not on a sensor at 00, the minor street cycle is not
> initiated. If you are turning right, pass the sensor at some other
> time in the cycle, and proceed with your right turn, the minor street
> cycle is not initiated. If you are going straight or turning left and
> you run the light, the minor street cycle is not initiated. Only if
> you are on a sensor at the moment it is checked does the minor street
> cycle get initiated.

That cycling method sucks.
At the least, it should check the sensor every 5 - 10 seconds.
Continue the light cycle normally.
If the sensor is tripped, change the lights accordingly.

In many locations, the sensors are practically checked constantly.
So as soon as a vehicle crosses one, the lights begin to change.

When I first began riding my bike in 1978, I found out quickly that many of
the sensors could not be tripped. In many cases I had to position the bike
over the corners to get it to trip.