While the science is sound and the new arrows can help alleviate traffic congestion, many Iowa drivers still have no idea what to do when they approach these intersections. They stop, they slow down, and some simply drive straight through without knowing exactly what’s going on or how to react.
This has caused some traffic engineers to scratch their heads in bewilderment at an idea they thought seemed reasonable enough, but is now causing almost as many problems as it was meant to solve.
The Iowa Department of Transportation is trying to educate motorists about the left-turn signals, which have been adopted as a national standard by the Federal Highway Administration. Sioux City has 25 to 30 of the traffic signals, some installed as far back as 2008. But elsewhere in Iowa, the signals are relatively new.
The city of Des Moines began installing flashing yellow-arrow signals last summer along Merle Hay Road and now has about eight to 10 signals throughout the city, said Mike Ring, the city’s principal traffic engineer.
West Des Moines began using the devices last December and has them at 10 intersections. Meanwhile, Clive shares some of the signals with West Des Moines on University Avenue, which is a border for the cities.
A few other cities have flashing arrow devices, but they are not widely used yet statewide, DOT officials said. In Missouri, state transportation officials have installed nearly 100 of the new signals in the St. Louis area and have reported positive results.