Slope Meter - SCSI The safe driving speed for any curve is quickly and accurately determined with the "SCSI" Slope Metermounted in the engineers car. The scale reads zero when the car is level, and will show "tilt" up to 25 degrees on each side. The scale is red beyond +/-10 degrees to denote danger zones. The "SCSI" was designed by Slope-Meter in accordance with the specifications of the Minnesota Highway Dept. Traffic Division and is used nation-wide by highway and traffic engineers.