TRAFFIC SIGNALS – THEN AND NOW
OH HOW THINGS HAVE CHANGED!
From: Gene Quinn
Sent: Thursday, February 01, 2001 9:15 AM
Subject: TRAFFIC SIGNALS – THEN AND NOW – OH HOW THINGS HAVE CHANGED
Traffic lights that turn red prematurely because of inadequate yellow time duration, especially when cameras are used, create a host of safety and equity problems.
A BRIEF SUMMARY ABOUT HOW THINGS HAVE CHANGED:
In 1976, you're sitting on a side street and you have a red signal. The mainline traffic gets the yellow. Some vehicles stop and some continue out of necessity. Vehicles that cannot stop continue across the intersection and they do so on the yellow. Sitting there on the side street you're satisfied and happy as people are doing what they need to do and doing it safely and you understand that. Although perhaps not perfect, thing works pretty well. What you see is what is intended by national engineering policy.
In 1994, with the “lets make the lights turn red faster method”, you're sitting at the same side street with everything being exactly the same, except for how the lights are timed (but you don't know that). The mainline gets the yellow and again some stop and stop continue out of necessity. Those that continue now move across the intersection on a red signal while you are sitting there seeing red yourself. Some will actually both “enter on red” and “clear on red” by design but you don't understand the dynamics of what happens or the calculations involved to appreciate that. Some continuing vehicles must now accelerate to avoid the impossibilities created by the new signal timing methods and you know that's dangerous. Sitting there on the side street you are now unhappy, maybe getting madder and madder as more and more places adopt the 1994 “reduced yellow” practice. As that happens, you see more and more people “running the red light” and can't figure it out but one thing is for sure, you can’t remember it ever being this bad and, guess what, you’re right. As far as you are concerned, you see drivers “running the red light” more and more and they naturally become a convenient target for your outrage. Camera enthusiasts are happy that you are irritated because now you are becoming more receptive to their ideas and plan.
In year 2000, you’re in California and sitting at the side street looking at the red. The mainline traffic gets the yellow and exactly the same happens as some stop and some continue out of necessity. As those that continue cross the intersection (with some still entering if you understand the dynamics and calculations), you observe that they are doing so while they have a red light and at the moment they got the red you got the green! That’s right, as a matter of standard practice by design, you watch those damn drivers going across the intersection (with some still entering) while you have the green. Now you are really pissed! And deservedly so for you recognize the impropriety and dangers involved. But you don’t realize that it happens by design and intent......because the camera enthusiasts never told you and you probably never thought to ask. This is the latest trend in signal timing decisions, giving the green to cross traffic while small numbers of vehicles are still entering and others are still moving through the intersection going the other way on the red. You are even more unhappy than in 1994. Camera enthusiasts are happier than ever.
No clearance time at all (forget about whether it should be yellow or red) is becoming trendy and is working it's way into national policy. “The red clearance Interval is an optional interval that follows a Yellow Change Interval and precedes the next conflicting green interval. The red clearance interval is used to provide additional time following the Yellow Change Interval before conflicting traffic is released.” (emphasis added) page 482 TRAFFIC ENGINEERING HANDBOOK – FIFTH EDITION by ITE 1999. The key word is optional. See what I mean?
If you are a pedestrian, especially on the far side of the intersection, you would see essentially the same thing as the driver on the cross street. You can imagine the terrible consequences that can result should you start across the street having assumed that “RED MEANS STOPPED” for the through moving vehicles, which it does not as you now know.
The above describes the trend in national tech codes for establishing signal timings, particularly the yellow time duration.
If you agree that what is happening is good, then so be it. Just keep in mind that someday you might be the one “running the red light”, with all the potential deadly consequences. Or you might be the pedestrian who starts prematurely across the street. Or it might be a loved one of yours. Or some day you or a loved one might be falsely accused by an observer who is equally mad as you were on the cross street in the above and is ripe for expressing their own frustration at all the “red light running” they have been seeing lately.......and they might do so by accusing you.
The people who say they are against “red light running” seem to keep doing things that increase “red light running”. For example, for 50 years at least engineers understood that you should establish signal timings to accommodate the speed at or below which 85% of drivers use the road, called the 85th percentile speed. The new MANUAL ON UNIFORM TRAFFIC CONTROL DEVICES by FHWA (released online 12/2000) but not in print yet, changes all that as jurisdictions can now use their underposted speed limits. When posted speed limits are not reasonably established they are underposted, meaning they are below what they should be. Using an underposted speed limit to establish yellow time can results in shortfalls 20% or more over the shortened amounts already embedded in the newer contemporary technical codes. Imagine yourself on the side street mentioned above. You will start seeing even more of what you don’t like to see, what you don’t want to see and what you know is dangerous. But remember, the camera enthusiasts are happy.
Keep in mind that while decent people who don’t know these things waste their time pointing fingers at other people who are decent for the most part, which the camera enthusiasts like to see, their is less time available for decent people to contact their elected officials (federal, state and local) and express their concerns about how dangerous intersections have become.
The same Federal Highway Administration that is making new policy that will increase “red light running” (see above) has identified you as a “red light runner”. Go to http://safety.fhwa.dot.gov/fourthlevel/pro_res_srlr_facts.htm and read for yourself. “Red light runners do not conform to a set demographic – the dangerous practice reaches across drivers of all age, economic groups and gender. The perpetrators are everyday people; professionals, blue–collar workers, unemployed, homemakers, parents, and young adults.”
An important question should be asked. “Who are the real aggressive people in this whole matter and why?” Red light cameras do not treat the cause, they treat the symptom and, in so doing, they generate a lot of money for a lot of people at your expense.
Be your own judge as to what is wrong with the picture.
Be cautious about people who may be taking calculated risks with your life without your knowing......GET INVOLVED.
PS Just something to think about gang and maybe alert those you care about to.