This figure shows a list of measures and their effectiveness, safety impacts, and efficiency impacts. (Submitted image)
KNOXVILLE— It’s a common driving predicament: As you approach the intersection, the light is yellow. Do you hit the brakes or face a red light camera fine?
Some municipalities engineer their traffic signals to force drivers into this situation in an effort to generate revenue from the cameras.
Professors at the University of Tennessee in Knoxville have analyzed this issue to determine if traffic control measures intended to boost red light revenue—such as shortening yellow light time or increasing the speed limit on a street—compromise safety.
The study by professors Lee Han, Chris Cherry, and Qiang Yang in the Civil and Environmental Engineering Department is published in this month’s issue of Transport Policy journal.
Most municipalities acquire their red light camera systems through private vendors and pay for them either through a monthly flat rate or a portion of citations. Thus, the more successful red light programs are at improving safety by decreasing red light running, the less profitable they become. This creates a predicament for traffic engineers—meet financial guarantees to sustain the programs, or increase safety?
“Traffic engineers are facing an ethical dilemma of balancing revenue generation to sustain their red light camera programs with their traffic safety and efficiency goals,” Han said. “This is a new conundrum for them.”
The authors analyzed prior research related to four traffic signal measures—shortening yellow duration and/or lengthening all-red duration, shortening cycle length, increasing the speed limit, and increasing high volume-to-capacity conditions such as with an unwarranted turn signal—and their impacts on red light running, safety, and efficiency.
Among their findings:
- Shortening the yellow and/or lengthening the all-red, shortening the cycle length, and increasing the speed limit increased the chance of drivers running a red light.
- Shortening the yellow and increasing the speed limit increased the chance of a crash.
- Shortening the yellow and/or lengthening the all-red and increasing the speed limit did not impact efficiency of traffic flow.
- Increasing high volume-to-capacity conditions increased the chances of traffic congestion at a signal but not the chances of running a red light or crashing.
According to the researchers, within the bounds of engineering design standards, there is room for traffic engineers to apply their judgment and develop the best signal timing strategy. They note that while each strategy has its merits and faults, a combination of the strategies could possibly produce adequate revenue without causing traffic delays or congestion.
“One of the major challenges with implementing red light camera policy is the conflict of matching incentives of tangible revenue for industry and the municipality contrasted with external cost savings such as safety and congestion, the value of which is not easily captured,” Cherry said. “We hope the public sector and the public use our research to reflect on the motivations for changing signal operations.”
This research was supported by funding from the Civil and Environmental Engineering Department and Southeastern Transportation Center at UT. To read the complete article, visit http://dx.doi.org/10.1016/j.tranpol.2013.06.006.
TJ Garland says
They did not mention that all studies show that lengthening the yellow light time by one second greatly decreases red light tickets- but that was not the goal of the study.
UT professors never do anything for free. Wonder who funded their study? KPD?
Robert Humphries says
Longer lights, shorter lights, etc. etc. The real problem is that it is about revenue, NOT safety, as I helped point out with many others in March of 2008 in Oak Ridge, when they were 1st considered. $50 fines do NOT reflect the seriousness of running red lights. The powers that be would LOVE to charge more, but state law states that it is a “civil” offense rather that a more serious charge, because it is a penalty caused by an electronic device, not an officer of the law. That is a good thing, or we would have RLCs on every street corner$ If a municipality is serious about safety, and really thinks that running RL’s is a serious charge, then they should monitor trouble spots with real cops, turn on the blue lights, run down the offender, and issue a citation for that serious offense. I have personally witnessed the semi-trucks taking the short cut though Clinton and Oak Ridge to I-40 running the red lights….on purpose! Their license plates are NOT on the rear of the truck, so they get away with it. Anyone care to be hit with a semi in the side at 45 mph? It’s not about safety. End the RLC’s! One of the Council Members in a recent meeting they had told me directly on another subject (paraphrasing): “Sure, I believe in the principles that you stated, but we HAVE to do those things, because ‘everybody else is doing it'”. Really? So much for the principles that our founding fathers worked so hard to give us.
Scott says
Is why i no longer spend a dime in Oak Ridge,and never shop in any part of Knoxville that has allowed these ways of Theft to be near their shops. If it was done for Safety is one thing, but when all know it was done to ripe off Citizens I am filled with disgust
Kay Williamson says
YOUR NOT THE ONLY ONE SCOTT, many people avoid oak ridge because of the SCAMMERS,, Redflex the company that has the one’s in OAK RIDGE HAS ADMIT TO BRIBERY, LYING, CHEATING, and that is with town officials,,, this doesn’t included what it’s done with CAMERA’S
Mark Caldwell says
Please slow down and do not exceed the maximum posted speed limit.
It really is that easy.
Sam Hopwood says
If it were really about safety why are they not installed at the two most busy intersections in Oak Ridge…. namely South Illinois/Turnpike and South Illinois/Lafayette Drive? Think about it.
Dave Smith says
Okay, I thought about it.
If it were really about the money why were they not installed at the two most busy intersections in Oak Ridge instead of near two schools and a hospital?
Mark Caldwell says
I wish those two intersections and several more in town had the traffic-enforcement cameras.
Johnny Beck says
I don’t know about Illinois and Lafayette, but the intersection of Illinois and the Turnpike was under construction when the cameras were put in.
Sam Hopwood says
Construction WAS the excuse at the time I believe. Stiil no answers as to why they are not installed at those two intersections now. I suspect DOE and Y-12 management would not stand for one at South Illinios/Layfayette. Just my view.
Jason Allison says
Just whatever you do folks, don’t abide by the law. I drive through each intersection on a daily basis multiple times a day and I have yet to get that dreaded envelope in the mail. who knows, could be the sweet warp drive in my Jeston mobile, or it just could be that somehow, just somehow, I don’t have an issue abiding the laws.
TJ Garland says
You WILL get a ticket. Do you phone talk while driving?
Jason Allison says
At the risk of sounding stupid, what in the heck are you talking about? Not only have I driven through each of Oak Ridges camera locations multiple times daily I drive up and down Cedar Bluff multiple times. like I said, must be that sweet warp drive in my Jetson mobile but I will have to say its probably more likely that I observe the laws. and to answer your question (as if it has anything to do with RLCs) no, I don’t use myphone unless its through blue tooth.
Johnny Beck says
So UT paid for a study that has been done numerous times all over the world, and they found the exact same thing every other study found: That increasing yellow light times and concurrent red light times and setting a proper speed limit all contribute to traffic safety at intersections.
Who’d a’thunk?
About the cameras themselves, I’d like to know how it’s legal to have different penalties for the same offense depending on how you were caught.
And to those who decide to protest the cameras by not shopping in Oak Ridge anymore, I have mixed feelings about your decisions. On the one hand, you are hurting Oak Ridge businesses and employees because of something that they had no say in. The amount of tax revenue you are depriving the city of is minuscule compared to that.
On the other hand, if you are taking your business elsewhere so that you don’t have to worry about getting a ticket, then good riddance and thanks for not hurting or killing my family with your selfish unsafe driving habits.