Bob Kelly of Snohomish writes: As frequent travelers of British Columbia’s high-speed Island Highway we have found very helpful their system of using timed flashing amber lights to warn drivers that the next signal light will be red by the time they get there. The warning gives all drivers time to slow down as they approach the signal and from our observations seem to eliminate red-light running.
It seems that this system could have a lot of benefit on some of our roads such as Highway 9, especially between Snohomish and Woodinville.
Bronlea Mishler, spokeswoman for the state Department of Transportation, responds: This is a question we’re asked from time to time. With a signal-activated warning light, drivers can become conditioned to react to the warning light, rather than the signal itself. This can become very dangerous if the warning lights lose power or become inactive for some other reason. This could easily lead to a high-speed collision at the intersection.
National studies have shown that collision rates at signals with activated warning flashers are about 10 percent higher than intersections that have continuously operating flashers.
Additional observations have shown that when drivers see that the warning flashers have activated, they tend to speed up in order to make it through the signal.
Again, this leads to the possibility of very dangerous high-speed collisions.
Highway 522 signals
F. L. “Pat” Jacobs of Snohomish writes: When the Highway 522 overpass was completed at Echo Lake-Fales Road, we were advised that the lights were not trip lights, but computer controlled. However, sometimes there seems no rhyme or reason to their operation there.
When exiting westbound from 522, to go south on Echo Lake Road, there are arrow lights. If you are stopped by the red arrow, when you get a green arrow, most of the time, one can barely make it through the light before it changes. If you are second in line, the yellow comes on before you ever get near it, and you end up “running a red.” If you’re third in line, forget it. That is most of the time.
Also, when northbound on Echo Lake Road, there are arrows for left turns onto westbound 522, and regular lights if continuing north onto Fales. Sometimes, you may stop for a red while the green arrows are lit, and then have to wait through two cycles of green arrows before getting a green northbound light. This is incomprehensible! It is frustrating when you are waiting for a light, and the lights next to you cycle more than once.
Mike Swires, state Department of Transportation traffic engineer, responds: I understand that it can be frustrating to have to sit and wait for a green light. We’ve closely monitored the operation of the intersection since it was opened to traffic in its current configuration. The layout of the intersection includes a very wide space that vehicles must completely cross before we can give a different direction a green light.
Generally, when a signal detects a vehicle waiting at a red light, it will start the process to give that vehicle a green light. It must wait for the direction that currently has a green light to either get every vehicle it detects through that light, or it must reach the maximum amount of green time we’ve set, then switch to the waiting vehicle. The typical signal cycle length can vary between 90 and 120 seconds at this intersection. The only way we can ensure that vehicles have enough time to safely cross the wide space at this intersection is by giving the Echo-Fales left turns a green light when switching. The current sequencing of the signal is as follows:
1: 522 offramps right turns
2: 522 offramps left turns
3: Echo-Fales through movement
4: Echo-Fales left turns
If, for instance, a vehicle was waiting to go straight through from Echo Lake to Fales, we first give the Echo-Fales left turns to 522 a minimal green light before switching — even if no one is waiting to make the left. This again ensures that any traffic in the intersection has adequate time to get all the way through it. We are continuing to monitor this intersection and are exploring improvements to reduce the waiting time drivers experience without compromising safety.
E-mail Street Smarts at stsmarts@heraldnet.com. Please include your city of residence.
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