Abstract
A field experiment was conducted in winter 2017-2018 using an automated vehicle equipped with adaptive cruise control (ACC), a vehicle for measuring lateral friction on the snowy and icy road surface using the Real-Time Traction Tool-Curve and a meteorological measurement vehicle, where various winter road conditions were recorded in Hokkaido, Japan. On an experimental route, we determined where the driver overrode the ACC and decelerated, an action we herein call a “driver interaction”. The study used an ACC-equipped vehicle to investigate how the road surface condition and the road configuration affect the likelihood of driver interaction in winter. The experimental route passed through two types of road: a nationally administered road, and a regionally administered road. Driver interactions were found to occur only rarely on the nationally administered road. Based on the results of this study, drivers are expected to be able to use an automated vehicle equipped with an ACC system in winter on roads whose geometric road design is on par with that of nationally administered roads, except under slippery road conditions on curves and slope sections.
