Background
With its sharp curves and intersecting on and off ramps, the interchange where I-64, I-65, and I-71 converge in downtown Louisville has always been known as “Spaghetti Junction.” Portions of this interchange have experienced a high rate of traffic incidents in the past, particularly large truck rollovers and car spinouts. Local officials were seeing numerous rollovers annually, which impacted road safety and caused expensive ramp closures and delays to motorists. In 2018, the District’s Traffic section started exploring ways to improve the situation.
The Search for Solutions
After thorough data collection and review of the area, both by observation and personal experience, the agency determined priorities based on the costs and budget. The Traffic Engineer encouraged his team to, “…think outside the box. Typically, if there is a known problem, the standard fixes might have already been tried, don’t be afraid to ask permission to try something new.”
The KYTC District 5 Engineering Team, started by studying the ramp to understand traffic volume and how people were navigating the curve. This led to a list of possible improvements, including changes to roadway striping and infrastructure to improve visibility in all different weather conditions.
Trying a New Approach
Major changes involved eliminating a lane ending merge within the problem curve and the reallocation of this pavement into two, exit only lanes, thus reducing conflict points and improving the curve geometry. In addition, it was determined that increased awareness and delineation was needed throughout the entire curve. To address lane awareness, they installed 3M™ Stamark™ High Performance All-Weather Tape for lane markings on bridges along with thermoplastic markings utilizing 3M™ All-Weather Elements. These products are designed for superior durability and visibility using high-index optics to be visible in dry and wet conditions.
Analysis of the collected data showed that it was imperative to make the curve itself more defined. To improve safety and provide better visibility, KYTC installed 3M™ Diamond Grade™ Linear Delineation System (LDS) panels throughout the curve. These LDS panels are engineered with a special corrugated pattern laminated with retroreflective sheeting. This reflects more light at different angles—making them perfect for applications where they needed to guide drivers through challenging curves. The panels were a low-cost safety improvement and met their safety goals and budget.
The KYTC District 5 team recently completed another similar project on a problematic curve on the I-64 West ramp to I-65 North. Here, 650 lineal feet of fluorescent yellow LDS panels were installed on the curve’s barrier wall – installation time was only three hours, utilizing two teams of three people each.
