McClanahan's Red Light Running Solution

E. Thomas McClanahan, conservative pundit of the Kansas City Star, in a commentary of January 4, 2009, stated that "Longer yellow-light times mean fewer violations and accidents." In addition to the "blinking green" and "point of no return striping" he has offered yet another idea as to how the problem of motorists disrespecting red lights can be solved. McClanahan cites several studies that reported decreases in intersection accidents after yellow-light times were lengthened, but he did not mention the duration of the previous yellow-light phase of the traffic signal cycle, the speed limit applicable at the intersection, the type of collision reduced, or any other of several factors that could affect the number of collisions. In other words, he focused solely on the length of the yellow-light phase of the signal cycle as the determinant of motoring safety.

The KC Star editorial board stated recently that the yellow-light duration at intersections where cameras are planned ranged from 3.6 seconds to 3.9 seconds and, that where cameras are installed, they would monitor the times to see if they are changed or not. Considering all the interest in the fairness and practicality of red-light cameras, it is time to look at some facts. At 35 miles per hour, the speed limit usually applicable on streets with traffic signals, a vehicle will travel 180 feet in 3.5 seconds or 205 feet in 4.0 seconds. According to national traffic authorities, the stopping distance for a car traveling 35 mph, assuming good brakes and a good road surface condition, is approximately 51 feet. From this data, it can be seen that a vehicle driver, who is not speeding excessively or is not physically impaired, has more than sufficient reaction time and braking power to bring a vehicle to a stop before entering an intersection.

A short ( one to two second) yellow light phase can present problems to speeding drivers, while longer phases (three to four seconds) are more forgiving of excessive speed. Lengthening a short yellow phase could be beneficial, but doing the same for a yellow phase that is already of ample duration would be unlikely to provide any benefit.

Personally, I consider red-light cameras to be a "two-fer", better traffic enforcement and more revenue, both of which Kansas City surely needs. If McClanahan really wants to "step up enforcement in the proper way-- with traffic cops issuing tickets at the scene", then I'll be looking for his commentary supporting a tax increase to pay the bill for his desire.

Blinking Green

A KC Star Opinion writer suggested that, rather than red-light cameras, a blinking green light phase be included in traffic signals. The idea is that the running of red-lights would be diminished by the addition of a light phase of blinking green before the light turns yellow, because drivers would have more warning as to when a green light was about to turn red, and thus, could be prepared to stop when they saw the yellow light. Recently, on this blog, I offered the idea that a "point of no return" stripe be painted across the lanes at the intersection to help drivers gauge their ability to stop upon seeing a yellow light. Both ideas have merits and faults. Detractors will say that the blinking green light would just encourage speeding up before the light changed, an act which would persist through the yellow light just as speeding up occurs now. The warning stripe would not be readily visible at night or during inclement weather and would be confused with a crosswalk marking.

So, what can be done to reduce the number of drivers who go through an intersection on the red? For one thing, we could encourage drivers to relax. What's the big hurry? It is not life or death whether one arrives at his or her destination a few minutes later than would happen with aggressive driving. For another thing, we could stress respect for the law at all times, even when driving. The rules of the road are designed to benefit all by providing safer travel. Aggressive driving makes for accidents and that isn't worth the repair cost or the anguish of injury or death that results from accidents. Finally, we should do more to enforce speed limits even if by means of direct control of car speed. I foresee the day when cars are equipped with radio-controlled speed governors that adjust their speed so it doesn't exceed the posted speed limit. In the meantime, radar controlled flashing speed indicators are an example of how technology is helping with enforcement. More effort needs to be applied to the problem of speed enforcement.

Solving the world's problems, one at a time.

Point of No Return

A motorist approaching a traffic signal that has just turned from green to yellow must make a decision - accelerate to clear the intersection before the signal turns red or brake to stop for the light. In an effort to arrive at their destination as soon as possible, aggressive drivers typically accelerate often entering the intersection at full speed after the light has turned red. They have violated a red light, risked or caused an accident, and confirmed a defensive driver’s need to hesitate before proceeding on a green light. Defensive drivers typically brake, resigning themselves to waiting through a signal cycle.

With the increase in traffic on city thoroughfares, the problem of scofflaws running red lights has become serious. In response to the problem, the use of video cameras has been introduced to detect traffic signal violators and issue citations. The decision to adopt ‘big brother’ techniques of remote surveillance has brought heated objections from some motorists, which is somewhat disingenuous, because the simplest way to avoid a ticket is to simply stop on the yellow. But, perhaps the opposition to cameras is not simply a desire to avoid a fine and goes deeper. Perhaps, the motorists who object to the cameras are reacting to feelings of fear and frustration. Upon seeing the light turn yellow, such emotions can be produced and run the gamut from not knowing whether they will be able to stop in time, whether they will be rear-ended if they attempt to stop, or whether they can speed up in time to clear the intersection and avoid being hit by cross-traffic.

There is a possible solution to the dilemma of decision/indecision posed by a yellow traffic light. As a motorist approaches an intersection with a traffic signal, a point of no return is confronted. Based on the road’s speed limit and the vehicle’s stopping distance, there is an imaginary line across the roadway before the intersection, the point of no return, past which a stop short of the intersection cannot be made or before which a safe stop is possible. I propose that a new traffic marking be placed at signalized intersections. I propose that a yellow band be painted perpendicular to the center line of the street approaching an intersection to indicate to motorists the location of that ‘point of no return’. The cross street marking would be an aid to the motorist’s decision-making, enabling safer vehicle operation and fewer inadvertent violations.

The location of the cross street marking could have buffers built into it. A vehicle speed 5 miles per hour above the speed limit, a rate at which most traffic seems to travel, could be used to calculate stopping distance. The braking ability of a vehicle could be based on trucks, rather than passenger cars. The cross street marking could be made of reflective materials to facilitate recognition at night. A roadside sign could be added to help the motorist locate the point of no return. If marking lines across streets before every signalized intersection was considered too costly for traffic control budgets, the fine for running a red light at an unmarked intersection could be increased as a deterrent. There are most likely other considerations that would need to be applied to this traffic control innovation, before it would be considered state of the art. The most likely consideration would be to paint the lines at a few prominent red light violation intersections for a test to see if it worked.

Solving the world’s problems, one at a time.