From tailgating to psychology to wives, explanations for seemingly inexplicable traffic jams on the drive north from Colorado Springs to Denver on the interstate ran the gamut.
Mark Dickerson, a physics instructor at Colorado Technical University, calls it the “Inexplicable I-25 Traffic Tieup” phenomenon.
“Something actually triggers IITT,” he says. “The trigger may be someone pulling a trailer onto the on-ramp who is having a hard time picking up speed. He or she tries to merge anyway, generating an evasive maneuver by another driver, whose rapid lane change causes the next person in the left lane to hit their brakes. Meanwhile, someone coming up from behind in the right lane hits their brakes to avoid hitting the slowpoke, and the person behind them is surprised and slams on their brakes as well. Chain reaction.”
IITT happens because we expect IITT to happen, Dickerson says.
“We can see a long way around here, and all of us a quarter mile behind this small incident see a bunch of brake lights suddenly coming on. ‘OMG,’ we say. ‘There IITT is!’ And we all start slowing down in preparation for what we knew was coming… and cause it to actually happen.”
And then, there’s Tim Melchior and the “freak out” factor.
He surmises that when a lot of cars are in the same area, “some will freak out and hit their brakes.”
“This causes the cars behind them to catch up, which cause more congestion and causes more people to freak out and hit their brakes which cause more cars to catch up which causes more congestion which causes more people to freak out and hit their brakes and causes more congestion, and so the process continues to feed on itself.”
Whew! That’s called word congestion.
“What people don’t realize when they don’t pay attention or freak out on the highway is that they are potentially starting a chain reaction that will affect hundreds of cars behind them,” Melchior says.
Brian Tunney blames his wife.
The cause of the congestion, he says, is a “dynamic related to female passengers.”
“For instance, my wife lets me know when she is feeling unsafe due to our proximity to other vehicles or speed of travel,” he explains. “This in turn nearly immediately changes the speed of our vehicle and its relationship to the distance of nearby vehicles by way of my foot control/moderation/alternate pedal options etc.
Simply put, her yelling and my cursing subside simultaneously. I think you know how this might affect numerous other motorists nearby with similar passengers. Darn near gridlock slowdown in the vicinity.”
Brian will be sleeping on the couch for the next month or so.
Douglas McNutt, a PhD with the MacNauchtan Laboratory, says it’s “not really much of a mystery.”
Then, being a scientist, he indulges in obfuscation, which makes it seem even more mysterious.
There’s milk and bubbles, the lift on an airplane wing and input parameters.
Then for people like me, he puts it in more simple terms.
“The reason for the traffic jams is simply the presence of more vehicles on a section of road than can be handled at the published speed limit while obeying the one-second rule,” he says. “That’s all. Nobody up there has to be doing anything but safe driving. Thirty vehicles per kilometer per lane is likely about right.”
Mike Witty sums it all up in one word, tailgating.
“The tailgating driver must overreact to any slight slowing of the car ahead,” he says. “In response, the car tailgating the tailgater overreacts. Each reaction is larger, until noticeable slowdown happens. Given enough traffic in a limited area (traffic density) the slowing outpaces the recovery and we’re all jammed up.”
One thing seems to be certain amid all this roadway lament, all the explanations in the world aren’t going to change things.
Steve Sinn from Manitou Springs doesn’t hold much hope for the future.
“My wife and I headed to Fort Collins a couple weeks ago and found the traffic jam we (you too) encountered at Woodman Road and it lasted until (on and off, more on than off) we got to Fort Collins,” he says. “Really, I could not believe it. No accidents, just every car in Colorado going to Fort Collins.”
Sinn says his son worked for an urban planner in Oregon and told him that research has shown that when cities build new highways or expand old ones, it helps for a while, then people start using that new capacity and it fills up all over again.
“The expansion north to Monument will help for a while, then it will fill up again,” Sinn says.
“Traffic – argh!”