In reply to:

My recollection is that the Tiger data is what Kim already tried with his software, and the lack of street directionality was a major problem.



I thought he said he had directionality turned off entirely at this point, but anyway...

DLGs can include fields for travel direction and speed limit. Standards for Street Centerlines explains how to use the data, however it appears to not be widely adopted. Interestingly Massachusetts seems to do something a little different and not as useful.

A few Xastir folks talked about trying to use this data to warn APRS users who were being tracked at higher than the speed limit. I'm still using Xastir in a mode where I don't broadcast, so how fast I'm going isn't being broadcast anyhow