Thursday, April 19, 2012

Traffic Signals

I left for work at 8:00am this morning and it took me 25 minutes to drive ~8 miles on Crenshaw Blvd. Sure there is a lot of local rush hour traffic but almost every traffic signal at a major intersection was red. Here is a list of all the traffic signals on Crenshaw and whether it was red or green on my drive this morning:

Crenshaw Blvd. Northbound:
235th St* - green
Sepulveda Blvd* - red
SCROC/Robinson Honda - green
Plaze Del Amo - red
Carson St* - red
El Dorado St - green
Torrance Blvd* - red
Maricopa St - red
208th St - green
Del Amo Blvd - red
190th* - red
405S on/off ramp - green
182nd* - green
Artesia Blvd* - red
Cherry/166th St* - red
Redondo Beach Blvd* - red
El Camino College - green
Manhattan Beach Blvd* - green
154th St - red
Marine Ave* - red
147th St - green
Rosecrans Ave* - red
135th St* - red
El Segundo Blvd* - red
Jack Northrop Ave - green

Whew. I was jotting down all the green signals on my iPad and had to verify the traffic signals using Google Maps Street View. Anyway, there are definitely more red lights (15/25 = 60%) than green lights (10/15 = 40%). However, if you look at major cross-streets (defined by a yellow road on Google Maps), the ratio is much worse with 11/14 = 79% red lights and only 3/14 = 21% green lights. Why? If there was no control, you would expect a 50/50 chance of getting a green light at major intersections, since Crenshaw is a major street. Assuming that major streets have a longer green duration than minor streets, I should expect more green lights than red over the entire trip (4/11 reds on non-major intersections).

Hmm. I thought cities timed traffic signals on major streets during rush hour to ease traffic flow. From my "experiment" this morning, it doesn't seem like there's much coordination. I drove through three cities (Torrance, Gardena, and Hawthorne) and they all seemed to not have any traffic light management. Of course this is only one (detailed) observation but from anecdotal experience, I notice that I hit a lot of red lights on my local commute both ways. It almost seems like there is coordination/conspiracy(!) to slow traffic... a lot of the red lights are full duration too, i.e., just turned from yellow to red as I approached the intersection. Seriously, I think I could save 10 minutes on my commute if there was some traffic flow coordination.

Maybe I'll start taking Prairie or Western in the future, even though it adds 2 miles to the drive distance.

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