How long is that green light?

May 16, 2008 10:11 AM

Help me find NYC traffic light times!

I'm trying to find data on New York City traffic lights. Basically, I want to know how long between red lights and green lights in different parts of the city from different years. Or really one single year would be fine. I know these studies are done cause I've read results from them in the past in newspapers, I'm just having trouble finding them. Can anyone help me find this stuff out? Thanks!

posted by Cochise to travel & transportation (8 comments total)

It depends on whether the signal is actuated or not. If it's actuated with a loop, sensor or camera then there is not really a time to it.
posted by JJ86 at 10:57 AM on May 16, 2008

Not sure exactly what you mean, but in New York the lights are automated, meaning they change (or are supposed to change) after a set amount of time, every time. No sensors or anything of the sort.
posted by Cochise at 11:03 AM on May 16, 2008

You could try asking the DOT.
posted by otolith at 11:10 AM on May 16, 2008

I think JJ86 means that in a lot of cities, a lot of lights turn green when a car approaches the white line instead of being on a timer. Though, usually there's a timer for the light- it just may change quicker if there's a car there. Also used for left-hand green arrows which can extend light times.
posted by jmd82 at 11:34 AM on May 16, 2008

Traffic engineers set them to different times depending a whole slew of factors. Theres no 'all yellows are 3 seconds' answer to this. You dont need sensors to do this either. If a certain intersection needs a longer yellow because of safety concerns then the timer is set to reflect this.

Its true NYC for some bizzare reason doesnt use loop sensors but they certainly do have varying timers on a per intersection basis. Although I could see an average of these numbers, but it would be misleading to put them all together. I wouldnt be surprised if these earlier studies were just averaging some random samples.
posted by damn dirty ape at 11:41 AM on May 16, 2008

Call 311

311 is New York City's phone number for government information and non-emergency services. Whether you're a resident, business owner, or a visitor, all the resources of New York City are just a phone call away...
posted by R. Mutt at 12:30 PM on May 16, 2008

Yeah, essentially lights can be set off automatically due to demand or on a timed sequence. Both depend on the time of day and traffic volumes. For example, flows during rush hours can vary immensely from non-peak times. So obviously a specific timed sequence is not the best solution for all times of day. As volumes change from year to year, new studies can determine a better optimization of light times.

On some segments, the lights are timed to allow for "platoon" progression which helps to spread out a dense pattern of cars and to help maintain speed limits.

I would talk to someone in the traffic department but with todays' climate of various threats, that request may be viewed suspiciously. Most engineers would be willing to explain how things may have changed at a random location over the years. You could also find archives of historic traffic studies which would list recommendations for optimized traffic signal times at the City Hall or the Public Library. I am not in New York but our City Hall library has lots of historic reports available for public viewing.
posted by JJ86 at 1:31 PM on May 16, 2008

New York is in the process of implementing sensors for certain bus routes that will extend light times as busses approach to move busses along faster.
posted by Jahaza at 9:08 PM on May 16, 2008