Cities Shortening Yellow Traffic Lights for Profit

[PonderInc]

When I lived in Colorado Springs in the early nineties, there was a huge gap (like 3 seconds) between when one direction turned red and the other direction turned green.  As a result, the unstated rule was: "3 cars go through on red."  If you didn't go, people would honk at you!  

When I came back to Tulsa, I almost got killed b/c I was still expecting to cruise through the "young" red lights.  It was a big shock to discover that the other people already had a green!

[mrhaskellok]

I am not an expert, but I think they are strobe sensors...for the Fire trucks...if you look at a fire truck head on while it is running code you will see a strobe light flashing above the windshield...that strobe is flashing at a precise frequency.  They then mount a camera like sensor that detects only that frequency.  The camera, when "activated" turns all the lights red except for the direction the fire truck is headed...ideally this clears intersections several seconds before the fire truck arrives.

[Wilbur]

quote:Originally posted by 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).

Consider yourself shocked!

Tulsa has traffic engineers who go to school for years and years to be trained in traffic engineering issues and traffic flow.  I'm confident Tulsa follows federal ANSI guidelines for signage, speed limits, road markings, .........  I'm also confident yellow and red lights are part of those standards.

As for synchronizing traffic signals, that is a luxury Tulsa would love to have, but is also extremely expensive.  It requires all of the signals be able to talk with each other, which they currently can not do.  Except for downtown, and a few intersections where traffic signals are close to each other, say on either side of I-44, and the one experimental synching happening on 71st Street around Memorial (paid for with a grant?), no other lights are currently synched, nor do they have the ability to without upgrades.

[patric]

quote:Originally posted by PonderInc

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?

The latter.  They are "machine eyes" to detect vehicles, replacing the loop of wire that had been embedded in the concrete as motion detectors.  They look like cameras 'cause they are.  Sgrizzle gets credit for that find.
Red-light cameras are still illegal in Oklahoma.

The sensors that preempt traffic signals to let emergency vehicles through are a whole different system, they look like this:

[patric]

quote:Originally posted by Wilbur

I'm confident Tulsa follows federal ANSI guidelines for signage, speed limits, road markings, .........

Maybe, maybe not.
If Tulsa were following ANSI guidelines for street illumination we would be using full-cutoff (low glare) fixtures (per ANSI/IESNA RP-8-00).
Im stunned that individual police officers arent behind such a standard.  If you visited a city that used Full-cutoff streetlighting you would be amazed at how much better (and further) you can see on the street.

[mrhaskellok]

I don't think officers, or any other majority of a workforce, thinks about stuff like that.  This is why I dislike the concept of 9-5s.  Your work and work load should be performance and result oriented.  We should pay our officers more if crime goes down and less if crime goes up...this incentivizes them to get involved in things like street lighting and such.

[Hawkins]

Only in a place like Tulsa would this even be a point of discussion.

In large cities, like Dallas, the yellow light means nothing, the red means, only three or four more cars can pass.

[}:)]

[si_uk_lon_ok]

quote:Originally posted by Wilbur

quote:Originally posted by 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).

Consider yourself shocked!

Tulsa has traffic engineers who go to school for years and years to be trained in traffic engineering issues and traffic flow.  I'm confident Tulsa follows federal ANSI guidelines for signage, speed limits, road markings, .........  I'm also confident yellow and red lights are part of those standards.

As for synchronizing traffic signals, that is a luxury Tulsa would love to have, but is also extremely expensive.  It requires all of the signals be able to talk with each other, which they currently can not do.  Except for downtown, and a few intersections where traffic signals are close to each other, say on either side of I-44, and the one experimental synching happening on 71st Street around Memorial (paid for with a grant?), no other lights are currently synched, nor do they have the ability to without upgrades.

Just to say that while synchronising traffic lights is expensive, the extra capacity it provides can usually outweigh the costs if the road is at or reaching capacity. It also needs detectors to run a smart system that doesn't trap you with the normal sequencing at 3am.

The move to cameras overhead rather than inductive loops buried in the ground is largely due to reliability and cost. The technology has improved the quality of IR or microwave radar systems which usually are more reliable and don't involve digging up the road to fit and replace. The loops also run into problems if the road is very wide.