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BYU study notes safety value of no-left-turn road medians

SHARE BYU study notes safety value of no-left-turn road medians

SALT LAKE CITY — BYU traffic engineers teamed up with the Utah Department of Transportation to address what they call one of Utah's biggest driving safety concerns: left turns.

Grant Schultz and Mitsuru Saito, professors of civil engineering, headed a study with UDOT to identify the safety impacts and benefits of installing raised medians between busy two-way streets, blocking left turns for drivers until they reach an intersection.

"Every time we have a vehicle making movement that crosses the path of another vehicle, then we have what we call a conflict point," Schultz said.

Schultz said with the addition of a raised median, those conflict points would drop from 32 to 4.

"We wanted to look at those safety benefits and simulation tools that are available to help us identify conflict," Schultz said.

Fifty-three percent of crossing-path crashes involve left turns, while only 5.7 percent involve right turns, according to federal data.

Schultz, who has been involved in transportation engineering for about 30 years, said he's spent the majority of his career looking at transportation impacts and safety.

"One of the biggest concerns we have in transportation safety is left turns," Schultz said. "I spent a lot of my career looking at left turns and identifying ways to improve safety and educate people about impacts and benefits."

Saito said a large number of accidents involving left turns are severe crashes. Consequently, replacing the middle turning lane with a median would reduce the number of severe crashes in that road's area.

But it wouldn't just improve safety, he said: "Adding this two-way left turn to a raised median includes the safety side and the operational side. Left-hand turns decrease the performance in traffic flow."

Saito and Schultz addressed one of the top concerns that come with adding medians: drivers might not have as easy access to businesses, potentially harming its income.

"The businesses are not necessarily affected so negatively," Saito said.

Schultz said he's done research over several years to look at the economic impact of installing raised medians in Utah and other states.

"The economic impact is actually positive," Schultz said. "Safer transportation systems improve business."

Schultz added that while road construction is a pain, his studies show the overall impact of installing a raised median on busy roads is positive.

"The biggest thing here is we're not trying to make life more challenging for people; we're trying to improve safety and make our systems operate and help all our residents in the state of Utah be safe in what they do," he said.

The study is part the UDOT research division's effort to identify new topics or concepts that can benefit Utah's transportation system.

"It really confirmed what we've known for a long time now that the elimination of left turns is in the best interest of safety," said John Gleason, UDOT spokesman. "But you can't always do it — it's not a one-size-fits-all application. We really have to look at every project that we undertake."

Robert Miles, UDOT's director of traffic and safety, said this study was not so much about the effectiveness of medians themselves, but was more about better analysis of when they are needed.

"We're well-aware that left turn movements are more risk-prone manuevers," Miles said. "But it's not something you can totally get rid of. We're focused on trying to find the safest possible ways to do that and still provide a convenient and effective transportation system."

Miles said this study doesn't necessarily mean Utah residents will be seeing more raised medians across the state.

"(Medians) are a prominent tool in our toolbox and we're going to use them when they make sense and when we can," Miles said.