Lateral vehicle placement as affected by shoulder design on rural Idaho highways.

During 1957, 1958, and 1959, lateral placement observations were made by the Idaho Department of Highways on bituminous-paved 2- and 4-lane rural highways having different shoulder designs. Placement data were recorded for 7,777 free-moving passenger and commercial vehicles at eight locations throughout Idaho. The study was made to evaluate the influence of shoulder design on vehicle pavement. Before-and-after data were recorded to measure the effect of shoulder striping and contrasting shoulders. Effects from other factors have been kept to a minimum by rational selection of study locations. Lateral placement on the roadway was recorded from visual observations of the vehicle in relation to 1-ft markings on the pavement. (A)