At rural intersections, vehicles traveling at highway speeds on major roads combined with vehicles crossing from minor roads creates ample opportunity for severe and often deadly collisions.
J-turns are increasingly a go-to solution for improving safety at these thru-stop intersections. A J-turn restricts a vehicle on a minor road from driving straight across a major highway or from turning left directly onto it. Left-turning drivers must first turn right and then make a controlled U-turn.
Despite their proven benefits, J-turns can initially confuse drivers—which makes education and clear signage critical for their successful adoption. A U of M research project exploring the best signage for J-turns was recently featured in a Minnesota Department of Transportation “Research Radar” webinar on driver behavior.
During the webinar, St. Louis County traffic engineer Vic Lund noted that the first J-turn in Minnesota was constructed in 2010. Last summer, the state constructed its 100th J-turn, “and many more are coming,” Lund said. “This is because they work. We’re seeing an 80 percent reduction, or perhaps even higher, in serious crashes at these intersections every time we install a J-turn.”
However, a driver unfamiliar with J-turns can make mistakes while navigating these intersections—which can also lead to minor crashes.
Nichole Morris, director of the U of M’s Human Factors Safety Laboratory (HFSL) and a CTS research scholar, is focused on helping drivers adapt. “J-turns are such life-saving interventions at high-risk intersections that it’s important communities are accepting of them,” she explained. “Initial errors at these intersections can create confusion for drivers, potentially poisoning the well for their acceptance…and leading to negative word-of-mouth discussions about them across communities.”
Morris’s research is exploring how to increase J-turn community acceptance, understand the risks of driver errors at J-turn intersections, and reduce driver errors through design and signage.
A previous study found that customized messages and powerful testimonials by trusted experts, such as local business owners and law enforcement, increased acceptance of J-turns. That study also used a driving simulator to assess how different levels of J-turn signage affected inexperienced drivers’ performance and attitudes.
Building on these findings, Morris’s current study investigates whether clarifying J-turn signage and road markings could help drivers navigate these intersections more effectively and improve their driving performance. Using the HFSL driving simulator, the research team is examining the effects of streamlined signage and pavement markings at two types of J-turn intersections: the extended U-turn and the compact U-turn.
“One thing we are looking at is ‘fishhook’ signage to really signal that [drivers] are approaching a J-turn and give a birds-eye view,” Morris explained. The team is also studying additional pavement markings for compact U-turns to guide driver movements directly into the deceleration lane.
The study has recently completed data collection, with 60 study participants (a majority with little to no prior J-turn experience) having completed the driving simulation. Preliminary analyses indicate that drivers made fewer observed errors when presented with fishhook signage. When presented with an experimental pavement marking, drivers were better able to immediately enter the deceleration lane on a compact J-turn. Additional study data analyses will determine the full impact of the new signage on driver interactions with each J-turn design type.
Morris’s team will also analyze video data collected in a before-and-after field study at a newly installed J-turn intersection in Minnesota. The team’s ultimate goal is to better inform sign design and pavement markings at J-turn intersections across the state—supporting driver decision making and safe crossing behaviors.
—Megan Tsai, contributing writer
