MONTHLY SPOTLIGHT - August 2021
Using Curve Safety Assessment Devices for High Friction Surface Treatment Site Selection in Georgia
HFST Pavement Treatment
(Photo Source: Georgia Institute of Technology, March 2020)
CHALLENGE: Roadway Departure crashes are a major emphasis area for Georgia. To address this crash type, the Georgia Department of Transportation (GDOT) investigated and implemented several solutions to crashes at locations with horizontal curves. One solution that GDOT is using to improve safety is the installation of high friction surface treatment (HFST) at curves where roadway departure crashes have the greatest likelihood of occurring. GDOT initially identified these curves using a traditional ball bank indicator. A traditional ball bank indicator uses a ball held in fluid that moves in response to travelling around a curve. This approach is both time and resource intensive requiring two to three workers (driving, reading, and writing). Therefore, a new approach was tested: a market-ready curve safety assessment device that utilizes an electronic ball bank indicator traditionally used for setting safe speeds at curves.
ACTION: GDOT rented the devices for each of its Districts to collect data on all curves on the road network. Once the data was collected, GDOT manually located each curve on the road network since data from the devices are imported as individual data points and may not be geospatially located correctly. GDOT used the data to determine potential safety projects.
RESULT: GDOT utilized HFST on several roadways across the state to reduce head-on crashes, sideswipe-opposite direction, and roadway departure crashes along horizontal curves. Eight roadways with HFST installed were analyzed, using the new curve safety assessment device, to determine the effectiveness of this safety countermeasure. The locations were in District 4 (Grady County), District 5 (Telfair County) and District 6 (Murray, Walker, Catoosa, Whitfield, Dade, and Cherokee Counties). While GDOT did not undergo an advanced statistical analysis of their crash reductions, a simple before and after analysis identified an average of 19 percent decrease in property damage only crashes and 49 percent decrease in injury/fatal crashes per year. Once curve data for all districts is collected, a data-driven process will be used to identify new locations for HFST projects.
Read the High Friction Surface Treatment Site Selection using Curve Safety Assessment Devices - Georgia Department of Transportation noteworthy practice.
Learn about more about High Friction Surface Treatments on the FHWA Office of Safety’s website: https://safety.fhwa.dot.gov/roadway_dept/pavement_friction/high_friction/.
Learn about more about how FHWA is addressing roadway departure and pavement friction: Enhancing Safety through Continuous Pavement Friction Measurement.