You might be surprised to learn that 84 percent of drivers speed on U.S. 278 on Hilton Head.
Or you might not.
Town of Hilton Head Island engineers requested a speed study from the South Carolina Department of Transportation in September 2018 to get a handle on how fast drivers are going on the main road that leads on and off the island.
That study came back with no recommendation from SCDOT that officials change the speed limit on William Hilton Parkway, which is 45 mph right now.
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But town leaders are itching to reduce the speed limit on sections of the road. They cite collision rates, unsafe conditions for pedestrians and an overall contradiction with Hilton Head’s “brand” — a relaxed community where it isn’t so obvious the island is bisected by a four-lane state highway.
“It’s a state road in our neighborhood,” Hilton Head Town Council member Bill Harkins told SCDOT officials at a meeting Thursday before asking how the town may be able to reduce the speed limit to 35 mph.
The speed study — presented by SCDOT district traffic engineer Josh Johnson — shows that the average speed on the road from Squire Pope Road to Sea Pines Circle is 49 mph.
In some places, 95 percent of vehicles are going above the speed limit.
Law enforcement or other measures?
Since most cars are traveling within 5 mph of the speed limit, Johnson said 45 mph is the appropriate speed limit.
“We are seeing a significant amount of speeding above limits,” Johnson said. “I think that has a lot to do with the limited resources of law enforcement.”
But Johnson said the speed study wasn’t developed to “point fingers” at the Sheriff’s Office, which had a rocky relationship with the town toward the end of 2018 after the results of an audit of the Sheriff’s Office duties led to a verbal sparring match between Sheriff P.J. Tanner and a consultant hired by the town.
Tanner — who was at the meeting — said the main causes for the 935 collisions between Squire Pope Road and the Sea Pines Circle in three years were distracted driving, inadequate lighting and roadside signage that’s too small.
“If you’re going to study speed as your main contributing factor to collisions, you’re off course,” he said. “Is it a contributing factor? Sure. But it’s not the same contributing factor that distracted driving offers.”
Tanner, who focused on stopping collisions in his remarks to the intergovernmental and public safety committee, said, “We have to look at heavy traffic; we have to look at road rage; we have to look at unlawful lane change; we have to look at too fast for conditions; we have to look at a variety for reasons.”
SCDOT officials disagreed with some town leaders’ calls to lower the speed limit. Johnson said to “neglect the engineering” behind the study and lower the limit would not slow people down.
“The travel speed is generally not affected by the change in speed limit,” Johnson said. He added that wanting to reduce the speed limit is typically a community’s response to speed studies.
Some members of the public said keeping the speed limit at 45 mph ignores the needs of Hilton Head’s pedestrian and bicyclist populations.
“I did not hear one word ... in the report about pedestrians and cyclists,” Patsy Brison, a resident of South Forest Beach, told town leaders. “Is the goal to move vehicles as quickly as possible from point A to point B? Or is (the goal) increasing public safety?”
What’s in the study
SCDOT performed the speed study via radar collection from 10 a.m. to 1 p.m. on Dec. 12, 2018, Johnson said.
The study was done on what SCDOT considered a “normal traffic day,” and the purpose was to measure the speed of cars when they’re less likely to be stuck in traffic.
To measure traffic speed on U.S. 278, the island was divided into three sections: Squire Pope Road to Northridge Drive (zone one), Northridge Drive to Mall Boulevard (zone two) and Mall boulevard to just East of Sea Pines Circle (zone three).
In each zone, SCDOT found the following:
- Zone 1: the average speed was 47 mph, and 68 percent of vehicles exceeded the speed limit.
- Zone 2: The average speed was 51 mph, and 95 percent of vehicles exceeded the speed limit.
- Zone 3: The average speed was 50 mph, and 89 percent of vehicles exceeded the speed limit.
In order to determine if the speed limit is right, engineers calculate the 85 percentile of the speeds recorded on the road. On U.S. 278, that speed was around 53 mph — which means 85 percent of drivers felt comfortable driving at or below that speed.
According to the study, the speed limit should be set more than 5 mph below the 85th percentile.