By Jim Baxter, NMA President
Intersection safety issues usually break down into four general problem areas. Each of these situations has unique qualities that defy a universal solution.
1) Red light violations just at the moment of signal change.
These are the bread and butter of ticket camera industry. They are also the most easily corrected violations. The vast majority of drivers willingly comply with traffic lights, and they want to comply — there is no coercion necessary.
This kind of violation is usually rectified by increasing the yellow light time a second or two.
To really do it right, a speed survey should be conducted to determine normal approach speeds for an intersection (85th percentile) and then starting with three seconds for approach speeds of 25 MPH or less and going up one half second for each five MPH increase in approach speed, up to six seconds. When approach speeds hit 40 to 45 MPH, an active warning sign properly placed upstream of the intersection is also a valuable tool.
2) Accidental entry later in the light cycle.
This sometimes involves impairment; drugs, alcohol, health, or vision. Distractions are another possibility — including noisy children, cell phone use, spilled drinks, tuning the radio and roadside activity. Fatigue can be a factor as well.
These are the kinds of crashes that often generate headlines. Serious injuries and fatalities.
There are several things that can be done to minimize these crashes, including:
- Making sure the lights are highly visible.
- Increasing the signal head size.
- Adding “backers” or other devices that help to differentiate the lights when there is high ambient light behind the light head (low sun in the east or west.)
- Using high intensity bulbs designed specifically for traffic lights.
- Removing tree branches, conflicting signs, of anything else that might obscure the traffic light will help to get the attention of the dull and distracted.
Clarifying signage and lane markings can reduce inadvertent entries into the intersection. Synchronizing traffic lights with the intention of minimizing traffic interruptions decreases the opportunities for accidentally entering on a red light. It also reduces travel time, fuel consumption, emissions, noise, and vehicle wear and tear.
This is also where an “all red” phase can sometimes be of value. Currently, all red phases are typically used to compensate for short yellow durations, but their ultimate value is more likely to be an empty intersection during an accidental entry.
3) Intentional entries against the light.
Intentional entries include:
- Emergency vehicles.
- Attempts to elude.
- Entries when lights fail to cycle.
- Entries during periods when there is no traffic.
As most people know, emergency vehicles can be equipped with devices that allows them to momentarily control traffic lights. This requires compatible signals. The same technology could be employed to address “attempts to elude” by shutting down all entries to relevant intersections. However, this latter application may not be currently available.
On occasion, smaller vehicles fail to activate the sensors that initiate a traffic light cycle. While this is an irritant to the affected motorist it is not a serious safety problem and some states have addressed this by allowing the motorist to proceed against the light when it is safe to do so.
A combination of newer signal technology, where light cycles are activated by the presence of vehicles, or the use of flashing yellow and flashing red during periods of very light traffic should largely eliminate illegal entries against the light when the light is really not needed for traffic control purposes.
4) Congestion inspired violations.
One of the most commonly mentioned red light violations in urban areas is the left turn after the light has turned red, even when there is left turn arrow.
There are multiple options to addressing this problem, but sometimes congestion is so severe that the only solution is to prohibit the left turn at this location.
Some possible solutions:
- Traffic light synchronization.
- Longer left turn arrows during peak traffic times.
- Right turn/U-turn combinations.
- More left turn opportunities before and after the problem intersection.
- Improve the underlying infrastructure.
Clearly, this kind of congestion problem is not improved by adding a red light ticket camera.
This short rundown on traffic engineering solutions to intersection safety problems is not the last word on this subject. However, it’s important to note that the suggestions and recommendations mentioned above actually address the causes of intersection accidents and propose proven solutions.
The ultimate “value” of these cameras is to generate revenue from the failure of communities to properly manage, maintain, and operate their traffic light systems. Hardly an ethical endeavor.
Image Credit: rawmustard