Teton Transplant

This is a call for volunteers to help measure and monitor the yellow light durations in Seattle.

I have set up a data entry form here:

The location of traffic cameras in your area of Seattle can be found here.

The results you submit will be posted here:

I measured the yellow light durations at the two intersections in West Seattle that have ticket cameras. Here are the results:

The above times are consistent with what has been stated by Wayne Wentz, Seattle’s traffic management director.  Seattle PI quoted him as saying that yellow signal times were shortened as part of a re-timing of downtown signals in March 2008, to make sure intersections are cleared of vehicles when lights change.

“Many of our downtown signals were operating with four seconds of yellow time, then going directly to green for the other direction,” Wentz said. “During our recent optimization, we changed the signals to 3.5 seconds of yellow time and added one second of red in all directions for a total of 4.5 seconds. This actually increased the vehicle clearance time by 0.5 seconds.”

The “all red” time at the two intersections I observed was about one second.  So that is also consistent with Mr. Wentz’s statement.

The 3.5 seconds of yellow is too short in my view for 35 MPH streets, and it is shorter than the 4 seconds recommended by others.  If borrowing a second or so from the green light would screw up the city’s carefully optimized system,  I would support moving .5 seconds from the all red period to the yellow light, at least on an experimental basis to gather data.  That would give drivers more time to make the stop-or-go decision, and still leave a half second of all red to allow the intersection to clear.

Seattle Time columnist Danny Westneat isn’t letting go of the stoplight camera issue.  He informs us that the state law enacted in 2005 that authorized stoplight cameras limits the fines that can be assessed to no more than what can be assessed for a parking ticket.  At least one sponsor of the bill expected the fines to be lower than the prevailing $124 to $189 range.  Westneat quotes Senator Mary Margaret Haugen saying the following when she introduced the amendment limiting fines to parking ticket levels:

“I know that some people would perceive that a local government would use this as a cash cow,” she said. “That is not our intention at all … What this amendment does is it restricts them, so that they cannot have a fine higher than their parking violations.

“Which is about — the state recommends $20. The idea is to change behavior, not collect a lot of money.

Of course, it’s the words of the statute, not a legislator’s intent, that matters.  Legislation has consequences.  It’s difficult, if not impossible to determine all of the effects.  Which is a good reason to “proceed with caution.”

I am creating a map to identify the location of stoplight cameras in Seattle and record the duration of yellow lights.   Feel free to measure the stoplights in your area and send the information to me in a comment to this post.
View Seattle Stoplight Camera Locations in a larger map

Record the following information (shown with an example):

Intersection: 35th Avenue and Thistle, S.W.
Street: 35th
Direction: northbound
Lane: left and right lanes (as opposed to turning lanes)
Speed limit: 35
Duration of yellow: 3.5 seconds

Make sure to use a stopwatch so you can look at the light. Measure it about five times and average your times. DON’T TRY TO DO THIS WHILE DRIVING.

According to this Seattle Times article, Seattle Councilmember Nick Licata wants to increase use of automated “speed vans” and red-light cameras to increase revenue from traffic tickets.

Traffic control devices or enforcement practices should be about promoting safety, not increasing revenue. Available data indicates that short yellow lights contribute to red light violations, and that traffic safety increases by simply increasing the timing of yellow lights. Of course if revenue enhancement, rather than safety, is your goal, short yellow lights are what you want. Which is why several cities were caught shortening yellow light times just to raise ticket revenue.

This article in The Atlantic, argues that America would do better to follow the British system, which is generally safer than ours, relying less on extensive signals and regulations, and more on driver attention, caution and judgment. The reason is that drivers can pay attention to only so much:

Economists and ecologists sometimes speak of the “tragedy of the commons”—the way rational individual actions can collectively reduce the common good when resources are limited. . . . But what is the limited resource, the commons, in the case of driving? It’s attention. Attending to a sign competes with attending to the road. The more you look for signs, for police, and at your speedometer, the less attentive you will be to traffic conditions.