Plenty of evidence signals need for better traffic control
By Jack Schnitzius
8/8/2012 12:33:34 PM
Splash Guest Column
Would someone please stop the insanity? Would someone in the Liberty Lake government realize they are in over their collective heads and they need the advice of a real traffic engineer? God bless him, but this isn't Chief Asmus' area of expertise. It doesn't appear to be Doug Smith's, either.
A real traffic engineer, consulting with, making the argument for and representing the city should be able to convince the "answer is no" bureaucrats in WSDOT that there are other criteria beyond traffic volumes to justify the use of a signal to control traffic at an intersection ("Seeking safe passage," Aug. 2 Splash).
As the chief points out, 24 accidents at Mission and Harvard roads in two years - many of them right-angle accidents - are more than enough to meet the threshold of the required five per year used by qualified traffic planners to justify a signal.
Dwell time, or delay studies, and gap analysis can also be used independent of volumes and collisions to justify a signal. This is based on the scientifically proven fact that the longer a person must wait at a stop sign, the greater risk they are willing to take to cross the intersection. Therefore, more accidents occur.
Spread, or distance between signals, is a consideration when installing a device. The distance to the closest signal at Appleway is more than enough to prevent back-ups and congestion, especially given the current technology of programmable and interlinked signal controllers. Much of the traffic heading north on Harvard Road turns right onto the freeway ramp before reaching the intersection of Harvard and Mission. The intersection of Molter and Appleway is a great example of demand-style programming.
In the 1970s and 1980s, "roundabouts" - we called them traffic circles in those days - were removed at major intersections because of the number of collisions and gridlock they produced. What replaced them? You guessed it, programmable signals!
While the traffic engineer is at it, he can recommend establishing realistic speed limits along the two stretches of speed trap roadways in town, Appleway and Country Vista. Realistic limits are set by looking at the 85th percentile of speed travelled by free-flowing traffic in the absence of law enforcement. This is based on the principle that 85 percent of motorists will travel at a safe speed given the conditions of the roadway and surrounding traffic conflicts. Sitting alongside the road in a silver Crown Victoria gathering data does not constitute the absence of law enforcement. Taking the measurement near an intersection where the speeds from vehicles entering from the side road are slower is also a no-no to a trained and qualified traffic engineer.
By the way, the 85th percentile speed taken along Country Vista, prior to the speed change and even under these flawed conditions, was over 42 mph, suggesting a realistic speed limit of 45 mph. Future development should not enter into the equation, as limits can be reestablished as conditions change. It is an ill-advised misconception that artificially reduced speeds contribute to traffic safety. The resources used trying to enforce an unrealistic speed can be better used patrolling our neighborhoods and businesses.
Finally, let's talk about cost. $1.5 million dollars can buy a lot of valid roadway improvements. Heck, $550,000 of city funds can do the same thing. Let's understand, there is no such thing as a free lunch. While the remainder of the funds might come from state or federal funding, it still comes out of the pockets of we the taxpayers. Please stop the delusion that anything from the state and feds is free!
And no, I'm not a traffic engineer, nor am I looking for a job, but I did stay at a Holiday Inn Express last night.
Jack Schnitzius lives in Liberty Lake. He originally wrote this column as a post on The Splash Facebook page. Join the conversation at www.facebook.com/libertylakesplash.