Remember, the speed to be posted shall be based on the results obtained from test runs with the ball-bank indicator (described later in this section),

not the calculated value

.

The posted speed shall be a multiple of 5 miles per hour.

In selecting the speed to be posted, care should be taken that the calibrated speed for any given speedometer reading is used rather than the speedometer reading itself. As a final check, the posted speed is aimed at the highest value that will permit the average car to travel around the curve in its own lane without causing an uncomfortable side throw to its passengers.

The speed to be posted on the curve should not be reduced arbitrarily below that determined by the procedures provided in this section.

When there is a reverse curve or a series of three or more curves, the advisory speed sign shall show the value for the curve having the slowest safe speed in the series.