Spent a few months on this dataset. Engineering Services collects traffic count data for various purposes. These counts were plot manually into a map. This is not ideal, and it would have been easy to collect X, Y coordinates at the time of the count, but the dataset only describes vaguely where the sensors were placed.
In these counts the yellow dots are
Low and the darker purples are
High. So arterial corridors are generally darker in colour as there should be a high amount of traffic. This was how i detected a problem in the dataset initially after auditing.