Driver Behavior Analyses of 2+1 Roads based on a Driving Simulation Experiment

The Korean government has moved forward with the application of 2+1 roads to mitigate traffic delays and offer safety improvements relative to the two-lane highway. Before beginning construction of the first 2+1 road in Korea, calls have been made to conduct driver behavior studies prior to implementing these roadway types within the existing road network. In this study, experiments using a driving simulator were conducted to assess driver behavior on 2+1 roads. The study results suggest several concepts to be integrated into 2+1 road design in Korea. First, drivers tended to decrease speed suddenly in both critical and noncritical transition zones so that lane changing information system is significantly important in 2+1 roads. Second, the speed change patterns on the 2+1 roads were different for driver ages, with greater variations in speed by older drivers. Third, the locations of speed reductions are related to the passing lane lengths. Sufficient passing lane length is necessary to increase capacity and may offer safety benefits based on the driver behavior analyses. Fourth, inappropriate design of a passing lane can lead to traffic operational problems, especially for older drivers. Finally, safety treatments including median-delineators should be considered in bad weather conditions including snow.