City Engineer Jenny Leshney said that when one of those stoplights changes from red to green, stopped motorists are given two seconds to get moving. If they don't react fast enough, the traffic lights' sensors cycle the light back to red, disrupting the flow of traffic.
Leshney said the widespread use of smartphones and Internet access has slowed motorists' reaction time when they use their phones while idling at red lights.
"It's created a situation where signals are not operating when they should," Leshney said.
She said her department has increased sensor-response time at seven major intersections from two to six seconds to give distracted motorists more time to notice that lights have changed from red to green.
Leshney said those seven lights are among 29 in the city that are interconnected and if one of them is "messed up" by distracted motorists that affects the 28 other signals.
"The problem perpetuates itself to many other intersections," she said. "It impacts everything downstream from there, so this is really getting to be a challenge when people are sitting at a stoplight and don't go."
Lafayette police Chief Pat Flannelly told the Journal & Courier (http://on.jconline.com/V3sKX9 ) that he checked out motorists at intersections to see the phenomenon for himself. He noticed people who pulled out their cellphones and stayed on them after stopping at red lights.
"I saw this over and over. This day and age, people are very attached to their social media and their smartphones," Flannelly said. "The technology that connects also really disconnects us in a way, because we aren't paying as much attention around us as we used to."
City traffic foreman Fred Koning said he was first alerted to the issue about year ago from a man who sat through several red-to-green traffic cycles at one intersection. That intersection is one of the seven that now has the six-second response time.
Lafayette resident Henry Mann said conceded that he will sometimes pull out his cellphone when stopped at red lights.
"A lot of times I use my phone for directions if I don't know where I'm going, and I'll look at the directions when I'm at a light to make sure I haven't missed a turn or something," he said. "I've been honked at a few times for doing it."