Area plot showing the distance to react and stop at various highway speeds


stop distance v. speed

Data on the website

table image


       The table itself is difficult to interpret: the column headings are not clearly aligned with the data, the extra lines are helpful for the numbers but not the text. The table doesn't indicate that some of the columns are simply sums of others.
        I have presented the data as an Excel 2007 'stacked area chart' that more clearly relates speed to both the time/distance required to react to a danger and to physically stop.
        The insight gained is that both reaction time and stop time are a function of speed but the latter is nonlinear (in fact proportional to the square of speed).
        Apparently the old rule-of-thumb that you need a car length for every 10 miles per hour no longer applies at today's levels of highway congestion


Code of Virginia § ยง46.2-880. Tables of speed and stopping distances.