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Speed limit sign

A motorcyclist passes a digital speed limit sign on northbound Interstate 270, a half mile south of the Dougherty Ferry overpass, on May 21, 2008. Photo by Adam Wisneski of the Post-Dispatch

TOWN AND COUNTRY • Electronic highway signs flashing “advisory” maximum speeds along Interstate 270 and Interstate 255 in Missouri will soon disappear. The Missouri Department of Transportation is expected to remove the 70 digital signs during the next two weeks. From May 2008 to June 2011, the signs were used to post enforceable speed limits that varied with traffic flow.

Drivers were cited for violating the original variable speed limits, and the changeable maximum speeds proved unpopular.

In fact, a study by researchers from the Missouri University of Science and Technology in Rolla found that nearly two-thirds of drivers wanted them eliminated.

Though MoDOT said the variable speeds made the highway safer, the study concluded that police did not think the system was effective in gaining speed compliance.

So the signs have been advisory-only for the past 2½ years. But MoDOT decided to remove them to lower operating costs and because the agency has received feedback that it would be less confusing to use the larger, electronic message boards.

MoDOT officials said Wednesday that 13 electronic message boards along I-270 and I-255 would be used to alert drivers of upcoming traffic slowdowns, along with the standard travel times to select destinations.

“We will continuously advise drivers of how fast or slow their vehicle should be moving in order to safely get to their destination, in the shortest amount of time,” said Tom Blair, MoDOT’s assistant district engineer. “The speed ahead message is similar to having advisory speed limit signs posted on curves and ramps. It is the suggested speed to safely travel that stretch of road.”

Blair said efforts would made to recycle components of the digital signs, which originally cost about $900,000 to install.

The overall goal is to reduce crashes, he added. There are about 150 crashes on I-270 in a typical month, making it one of the most conducive to accidents in the St. Louis region.

“That’s too many,” Blair said, “and that’s what we’re after here.”