Cities Shortening Yellow Traffic Lights for Profit

[patric]

http://www.motorists.org/blog/red-light-cameras/6-cities-that-were-caught-shortening-yellow-light-times-for-profit

Does this sound familiar?
And now even TPD is on record wanting synchronized signals in Tulsa:
http://www.fox23.com/news/local/story.aspx?content_id=dcbd32ed-86b3-4399-9fc6-26caa7c0c017

Wow, they must have found another revenue source
[)]

[TURobY]

How does them increasing the amount of time that the intersection is clear have anything to do with the shortening of yellow lights in six other cities?

[Wilbur]

quote:Originally posted by TURobY

How does them increasing the amount of time that the intersection is clear have anything to do with the shortening of yellow lights in six other cities?

DITTO!  Nor does Tulsa use red light cameras.

[Hoss]

quote:Originally posted by Wilbur

quote:Originally posted by TURobY

How does them increasing the amount of time that the intersection is clear have anything to do with the shortening of yellow lights in six other cities?

DITTO!  Nor does Tulsa use red light cameras.

Yet.....

[patric]

Tulsa has yellow-light intervals shorter than the national average, even though it is not on that list.  It appears local newspapers or TV reports are the ones bringing this to light, with the collection of traffic revenue at the heart of the problem.
The FOX23 story on timing lights only mentioned adjusting the red intervals so that they overlapped (without mentioning that the yellow intervals were too short, another known traffic problem).  They need to follow up.  

If the engineers are there with their heads in the boxes adjusting the red intervals, the same effort could be made to correct the deficient yellow intervals, but their reason for not doing so may not be based on legitimate traffic engineering needs.  


State law says operators, not vehicles, commit traffic infractions, so you have to issue tickets to drivers and not cars.  Its the reason we havent been sucked into the red-light camera scams plaguing other parts of the country.
How that's exceptioned to allow Pikepass automated ticketing and parking tickets issued to vehicles I just dont know.  

That's just as good we dont have red-light cameras, because a lot of cities have had to spend more money removing them because they have actually been known to increase accidents, and many have just flat become unprofitable.

[Wilbur]

quote:Originally posted by patric

Tulsa has yellow-light intervals shorter than the national average, ....

Please, tell us how long Tulsa's yellow light intervals are and then tell us your source.

[Chicken Little]

Point of order, please.  "Sychronized signals"  is something else.  It's not the duration of an individual red or green light, nor is it the pause between switching.

Synchronized signalling is the coordination of a series of lights so that traffic moves at a slow steady pace and doesn't get stuck idling at lights.  It's like we have downtown on Cincinnati and Detroit; if you drive 17 miles an hour you'll hit every light.

I think this is an important distinction because what Patric is talking about sounds like a bad thing.  

But signal synchronization where it has happened, has reduced drive times and helped get places back on the air attainment list, which sounds like a good thing.

Outside of downtown, our signals are not synchronized, I'm pretty certain.

[joiei]

I think I have found the source of patric's warnings.  Now, patric, go to some intersections and do some timing and come back and report to us.  Are the yellow lights 4 seconds or 3 seconds or something different.  I have noticed short greens but never short yellows.

[nathanm]

quote:Originally posted by joiei

 Now, patric, go to some intersections and do some timing and come back and report to us.  Are the yellow lights 4 seconds or 3 seconds or something different.  I have noticed short greens but never short yellows.

And equally important, but often forgotten, what is the 85th percentile speed of freely flowing traffic on the given road?

That's what yellow light timing should be based upon.

[patric]

quote:Originally posted by joiei

I think I have found the source of patric's warnings.

That does look a lot like the URL I cited at the top of the thread.
Im also surprised a Tulsa cop would not know the yellow light interval of his own town, but I guess Im as capable of using a video camera to document it as anybody.

As for other cities,
California mandates a minimum of 4.3 seconds, http://www.thenewspaper.com/news/06/670.asp
Denver is switching to 4.3 seconds (or more) to reduce collisions, http://www.rockymountainnews.com/news/2008/mar/29/city-may-yield-to-longer-yellow-lights/
Chattanooga, TN is 3.9 seconds,  http://www.thenewspaper.com/news/22/2269.asp
Dallas is 3.5 to 4 seconds, http://www.thenewspaper.com/rlc/docs/2007/kdfw-rlcdallas.pdf
Washington DC is 4 seconds,
and so on.

Some quick searches turn up some background on traffic light timing:

Historically, amber times have been set between three and six seconds, depending on a host of variables from the posted speed at an intersection to the grade of its approach.

The formula for these standards comes from a hodgepodge of recommendations by the Institute of Transportation Engineers (ITE) and the Federal Highway Administration's "Manual on Traffic Control Devices." To give just an inkling of how things have changed over the years, in the mid '70s, the Institute of Transportation Engineers recommended a yellow time long enough to factor in reaction time plus stopping time plus "clearance time," or the time it takes to get through an intersection.

But by the late '90s, that standard had been steadily eroded by altogether shaving off clearance time, lowering yellow light intervals by as much as a third, which often leaves the motorist stranded in the dilemma zone. To make matters worse,
the ITE, which in 1985 was still recommending yellow lights be lengthened to help clear intersections, now, with the advent of red light cameras, offers that "enforcement can be used instead."

The real-world translation here is that according to 1976 practices, an 80-foot-wide intersection with a 35 mph approach on a 2.6 percent downhill grade would warrant a five-second yellow light interval. But according to 1999 formulas, it is considered acceptable to allot the same intersection a 4 second interval.

[sauerkraut]

I think many reds are too long on the main Tulsa  drags, and arrows for left turns when no cars are there making a left turn is bad and senseless. Remember, no matter what kind of old heap you tool around in, a idling engine always gets zero miles per gallon and pollutes more... Arlington, Texas did something great back in the mid-1980's that they called "things that go blink in the night"- They made many of the traffic lights all flashers in the wee hours of the morn. It improved traffic flow alot for night shift workers. I don't know if they still have that program or not. None the less many more traffic lights in Tulsa can be blinkers over night.

[Wilbur]

quote:Originally posted by patric

quote:Originally posted by joiei

I think I have found the source of patric's warnings.

That does look a lot like the URL I cited at the top of the thread.
Im also surprised a Tulsa cop would not know the yellow light interval of his own town, but I guess Im as capable of using a video camera to document it as anybody.

There is no ordinance that mandates the length of a yellow light and that length is determined by traffic engineers, not police officers.  

I'm simply asking for proof of the comment

 

quote:  Tulsa has yellow-light intervals shorter than the national average

.

Please tell us what the national average is (please don't quote just three or four different cities), then tell us what Tulsa's is.  I may agree with you (but doubt it).

[patric]

quote:Originally posted by Wilbur

There is no ordinance that mandates the length of a yellow light and that length is determined by traffic engineers, not police officers.

I never stated that yellow light intervals were determined by police officers, that was your inference.

However, I would be somewhat shocked if any effort to either reduce yellow light intervals for the purpose of increasing citations, modify red-light intervals or synchronizing lights for better traffic flow was done without consultation with the department that ultimately has to deal with the outcome (being the PD).

[BKDotCom]

quote:Originally posted by Chicken Little
Synchronized signalling is the coordination of a series of lights so that traffic moves at a slow steady pace and doesn't get stuck idling at lights.  It's like we have downtown on Cincinnati and Detroit; if you drive 17 miles an hour you'll hit every light.

Outside of downtown, our signals are not synchronized, I'm pretty certain.

Cincinnati is no longer sync'd.
Supposedly 71st west of Memorial is sync'd.

[PonderInc]

Downtown needs sensors, not synchronized lights.  Nothing worse than trying to traverse downtown "against the lights" late at night.  (Though it IS fun if you can "catch the wave.")

I have a question about the camera-looking-thingies that I'm seeing all over town.  Are those cameras for discouraging running red lights?  Or are they sensors to detect traffic at the intersections?