file/staffTraffic comes to a halt on Interstate 26 as it approaches the Interstate 526 interchange.
COLUMBIA —South Carolina’s highway planners have more insight than ever into how congested our roads are, thanks to the phones, navigation devices and other personal electronics that we carry with us in our cars each day.
And this data confirms what many Lowcountry commuters know too well: The Charleston metro area has many of the state’s most clogged roads.
In fact, almost half of the 20 most congested interstate and non-interstate segments in the state are found in Berkeley, Charleston and Dorchester counties. U.S. Highway 17 between Interstate 26 and downtown Charleston and the Mark Clark Expressway at Interstate 26 sit atop the list.
And the data — mined from the same sources that are used to create the real-time television and smartphone maps with red-, yellow- and green-colored roads — also is providing insight into the success of road projects as well as other solutions to ensure that traffic continues to flow as well as possible.
And that will become an increasing challenge as South Carolina’s economy continues to grow, said Dipak Patel, who directs the state Department of Transportation’s system performance management.
“Can we beat congestion? No, we can’t beat congestion,” he said. “There will never be enough funding to do that.”
Transportation planners didn’t get serious about measuring congestion until the 1960s, said Tony Voigt, a research engineer with the Texas Transportation Institute in Houston.
That’s when California’s traffic planners began installing inductive loops into many of that state’s roads — metal strips that sense a change in the magnetic field when a car or truck passes over them. These loops — commonly found today in the roadway at many traffic lights — provide a traffic count and can even measure speed if they’re spread about 40 feet apart.
They also work like pneumatic tubes, which use air instead of electricity, but those tubes are used mostly for temporary measurements because the tubes’ rubber will decay over time — especially when pounded by thousands of car and truck tires.
Voigt said the technology of measuring traffic has evolved over the last 40 years to incorporate radar and video analytics and, most recently, communications technology.
During recent years, motorists buying GPS units like TomTom, trucks with their own locators and smartphones have increasingly painted a real-time picture of traffic flow on every road during every minute of the day.
South Carolina started using so-called “big data” in 2008, Patel said, and the quality of it has improved in recent years — just as the state was emerging from the Great Recession and traffic volumes across the state began growing again.
Voigt said the big-data measurements have really found their way in the last several years. “It’s relatively new,” he said.
Patel said the state began using this traffic-flow data in 2008.