Kimma Harper, who owns Driving Academy of Northwest Arkansas in Springdale, wonders if yellow lights in Arkansas are on for less time than in Kansas City, Mo.
It felt like the Kansas City yellows were longer when she drove there, and driving instructors pay attention to these sorts of things.
The Guru knows the answer, and here’s the deal.
The Manual of Uniform Traffic Control Devices says, “The duration of the yellow change interval shall be determined using engineering practices.” That’s the guidance followed in Bentonville, said Brad Conley, the city’s signal technician.
Conley did a quick check of 15 traffic lights in Bentonville and they had yellow times that ranged from 3.5 to 4.5 seconds.
There’s another factor to consider, and that’s the so-called “red interval,” which is how much time lights all four directions are red. Bentonville signals are mostly 1 second for that, but there are some 1.5- and 2-second “all reds,” Conley said.
Mark Lyons, a traffic engineer for the Arkansas Highway and Transportation Department, said a 3.5- to 4.5-second yellow light is typical statewide. Usually, a street where the speed limit is higher will have longer yellow times, Lyons said.
As for Kansas City, there’s no special effort to have long yellow times, said city spokesman Danny Rotert. They shouldn’t be much different than yellow times in Arkansas, he said.
THREE-WAY STOP
Drivers who take Wagon Wheel Road to the west so they can go south on Interstate 540 won’t be happy to hear that the Highway Department plans to leave an intersection just like it is.
Greg Smith, who commutes from work in Lowell to his home in Prairie Grove, thinks a three-way stop where Wagon Wheel Road meets Puppy Creek Road makes sense, but the state conducted a so-called “warrant study” and determined the intersection is best left alone. Currently, drivers going west on Wagon Wheel are the only ones who must stop, and it’ll staythat way.
The Wagon Wheel-Puppy Creek intersection was within an eyelash of meeting the minimum criteria necessary for the state to take a closer look at whether changes are needed.
A key standard for deciding if an intersection needs a three- or four-way stop is its traffic volume.
To meet the minimum requirement, an intersection must have at least 300 vehicles an hour on its major street (Wagon Wheel) at least eight times during a 24-hour period and at least 200 vehicles an hour on its minor street (Puppy Creek). The intersection met the hourly requirement six times.
How close was it? The Guru reviewed a report of the Highway Department’s traffic count and determined Wagon Wheel averaged 314 hourly vehicles and Puppy Creek averaged 234 from 7 a.m. to 8 p.m., but that high average doesn’t trump the eighthour rule.
Robert J. Smith, aka The Guru, writes on traffic issues in Northwest Arkansas on Fridays. He can be reached at nwaonline.com/guru or [email protected].
Northwest Arkansas, Pages 13 on 05/27/2011