Fig. 7
From: Effects of weather conditions, light conditions, and road lighting on vehicle speed
The data from Tables 9 and 10 plotted against the posted speed limits. Differences in speed in darkness or twilight light conditions compared with the speed in daylight at the same TF measuring station are plotted against the posted speed limit (top row; “Light cnd.”). Differences in speed in rain or snow compared with the average speed in clear weather are also plotted against the posted speed limit (bottom row; “Weather”). Differences given in km/h (a and c) and as percentage (b and d). Regression line is shown in black