There's a good source for California accident data (which probably has most of the street typologies of interest) here:

http://www.tims.berkeley.edu/ (signup is annoying but automatic, I can send copy or postgis dump)

It might require some work to categorize streets by design types, or it might make sense to use something like this as a reference:

http://www.sfbetterstreets.org/design-guidelines/street-types/ (just emailed Paul Chasan at SF planning about the underlying data for this)

It would be pretty straightforward to compare accidents per street type in CA as a base reference, but properly weighting for total volume of all kinds of traffic would require data that I don't know how to get yet (although I suspect that big roads induce usage, so "controlling" for traffic patterns as some kind of exogenous factor is maybe a mistake that is already made too much.)

I got some great data from Paul, the source files for the sfbetterstreets.org maps are now here:

http://sfgeo.org/data/contrib/street-types/

via @baronjutter in issue #57:

Instead it would be nice to have lanes rated for certain speeds. A narrow urban lane with a 40kph speed limit is very different from a highway lane or 60kph arterial. Have a little description for each item explaining it's use and "stats"