A study performed by Davis and Fitzpatrick of Minnesota Mining and Manufacturing Company, in conjunction with the Minnesota Highway Department in 1952-1953, measured changes in reflectivity of highway sign materials due to "spray" and "splash" on a two-lane, rural highway with turf shoulders. The report, entitled "Sign Placement to Reduce Dirt Accumulation" is presented in HRB Bulletin 89, "Night Visibility", 1954.
The purpose of this study was very similar - to investigate the pattern of spray from passing vehicles with respect to determining the optimum lateral and vertical placement of milepost markers for an Interstate-type highway with wider, paved shoulders.
