File talk:949.4.2 Driveway Conflict.jpg

Where did this driveway conflict curve come from or what equation was used to derive it? I have not been able to find anything in HCM or AASHTO Green Book as to where this came from.

Keith L. Smith: Thanks for the question. Here is Traffic Division's response:

This chart may pre-date me... I know it has been a part of our prevailing speed determination for a long time. My best guess is that it came from a publication like NCHRP. The intent is to try to quantify the impacts the number of driveways would have on the operation of the road. With new research in this area, and publications like the Highway Safety Manual and software like USLIMITS, it is something we should review. Not much help, but it is what I know...