From: Gene Quinn
To: San Diego Union-Tribune
Sent: Sunday, December 03, 2000 8:16 AM
Subject: "Red-Light Runners" - Your article 4-16-2000
Dear San Diego Union-Tribune:
I see from your article that red light cameras are catching on out there on the west coast. There are a few things you and your readers should know about this issue.
In 1985, to pave the way for camera enforcement, the camera enthusiasts formally proposed in the nation's capital a change to the national engineering codes to reduce yellow time on the lights. The reduction can be as much as 30-40%. That means the lights would turn red that much faster in those jurisdictions that might eventually adopt the proposed practice. The proposal was not approved/adopted because it could not garner a peer review consensus amongst the technical people. However, the proposed practice was nevertheless revised and printed as part of a technical report in 1994. In that report the proposed practice of reducing yellow time on the lights was given "top billing" and the previous national standard was relegated to a mere 3 short paragraphs, almost as an after thought. The 1999 edition of a national technical handbook portrays only the practice of reducing yellow time on the lights. The national standard that existed for years is essentially disappearing from print. You might have noticed in your area that the current "red light running" epidemic commenced essentially in parallel with the dates noted. Of course, common sense dictates that making the lights turn red faster will invariably increase the incidence of "red light running", along with attendant consequences.....dangerous intersections. Camera peddlers and enthusiasts, while at the same time expressing their shock at the resulting "red light running" epidemic, stand by with their very own cameras at the ready.
In your article it states "Before the cameras are put into place, city engineers make sure the lights are timed correctly, giving motorists adequate time to stop, given the speed limit of the road".
1. The national codes use a one second reaction time in the calculations for stopping. A one second reaction time is a 53rd percentile driver reaction time. That means 47% of drivers are predisposed to failure when it comes to responding to the signal color indications, particularly the yellow indication.
2. The national codes proscribe a formula for "brake time" that is impracticable and unreasonable. "Brake time" is the time that brake pedal pressure is applied when coming to a stop. For example, a driver is expected to stop using a mere 2.93 seconds of "brake time" from a speed of 40 MPH. Get a stop watch and try that sometime and then ask yourself if it is reasonable to expect drivers to expose themselves to such a dangerous maneuver. Ask yourself if it reasonable and practicable or anywhere close to normal. For reasons obvious to those who try it, most drivers reject the option of stopping this way.
3. Most jurisdictions calculate the required yellow time using the speed limit and not the 85th percentile speed from a speed study. The 85th percentile speed was long ago established as representing normal driving. Speed limits are supposed to be set to the 85th percentile speed, rounded (usually, but not necessarily, upward) to the nearest 5 MPH increment. Many speed limits today are underposted. Using underposted speed limits, and not the 8th percentile speed, in the formula for stopping, results in inadequate yellow time duration on the signals for stopping. The 85th percentile speed, or the posted speed limit, whichever is greater, should be used when assessing the yellow time needed for stopping.
4. Top end truncation of yellow time - The Manual on Uniform Traffic Control Devices (MUTCD) by the FHWA specifies a yellow time duration of up to six seconds, this amount generally being for higher speed approaches. The Traffic Control Devices Handbook by FHWA (1983) defines high speed approaches as those with approach speeds over 35 MPH. Engineering handbooks for generations have recommended, contrary to the federal code noted, a maximum 5 seconds of yellow time on a signal. Some jurisdictions adopt top end limits to yellow time of less than five seconds. As you can see, when the required and needed amount of yellow time is arbitrarily truncated below the amount needed, it is a conscious decision to allow "entries on red" and/or movements of vehicles through the intersection on a red indication.
On page 5 of Determining Vehicle Signal Change and Clearance Intervals by the Institute of Transportation Engineers (1994), regarding yellow time duration it states "When the percentage of vehicles that enter on a red indication exceeds that which is locally acceptable, the yellow change interval may be lengthened (or shortened) until the percentage conforms to local standards, or enforcement can be used instead". You see, you can correct the lights or install cameras. That so many communities chose the camera option is disappointing.
The yellow time on traffic signals today is considerably less than it was just a few short years ago, at least in those jurisdictions that adopt the practices of the camera peddlers. Less yellow time means the lights turn red faster, creating a statistically larger pool of "red light runners" to issue citations to. This scheme is dangerous and deceitful. I have stumbled on some jurisdictions that issued hundreds and thousands of tickets, citing those citations when bragging at the time about how well the cameras were working. Later, the yellow time was increased (quietly and without fanfare) but nobody wants to talk about that. I am concerned that much of the reduced "red light running" attributed to cameras may be the result of after the fact and unannounced increases to the yellow time on the lights and not because of the cameras at all.
The current methods of establishing yellow time for traffic signals provide for, some would say encourage, "red light running". Establishing the duration of the yellow signal indication so as to provoke driver failures and then turning around and measuring the outcome with a camera to collect money is wrong. What do we say to a driver in an accident falsely accused by bystanders, unknowing of the aforementioned, of "running a red light". Why are we so eager to portray people this way. What do we say to someone on the far side of an intersection who is injured or worse because they stepped into a crosswalk based on signal indications that imply that vehicles are stopped when in fact it is intended by design for them not to be?
When someone says that signal timings are timed correctly, the real question is from who's perspective and on what basis?
National Motorists Association