# Why Don't All Cities Synchronize Their Traffic Lights?

**URL:** <https://boards.straightdope.com/t/why-dont-all-cities-synchronize-their-traffic-lights/93034>\
**Category:** Factual Questions\
**Created:** [November 13, 2001, 1:36am UTC](https://boards.straightdope.com/t/why-dont-all-cities-synchronize-their-traffic-lights/93034 "2001-11-13T01:36:10Z")\
**Posts on this page:** 1\
**Page:** 2

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**Author:** ![RGillen](https://avatars.discourse-cdn.com/v4/letter/r/848f3c/32.png) [@RGillen](https://boards.straightdope.com/u/RGillen)\
**Post date:** [November 13, 2001, 7:56pm UTC](https://boards.straightdope.com/t/why-dont-all-cities-synchronize-their-traffic-lights/93034/21 "2001-11-13T19:56:30Z")

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> [@](#):
>
> \*Originally posted by drachillix \*  
> I guess the coolest thing would be to invent some kind of affordable networked sensor system so that a central computer could monitor traffic flow and keep things moving consistently no matter what time of day by modifying light duration as needed.
> 
> Are there any cities that use something like this? \*\*

I personally don’t know of anything this sophisticated, but lots of places have lights with different timing based on the time of day (rush hour, middle of the night, etc.). Also, you’ll see that some lanes, especially left turn lanes, will have a ground sensor right at the light and another one several car lengths back so the light “knows” roughly how many cars are waiting for it.

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