Statewide Integrated Traffic Records System (SWITRS) is a database maintained by the California Highway Patrol. It contains extensive collision data from all over California, and is a powerful tool for transportation planners and bike/ped advocates.
The CHP is not very skilled at web design. Their web site is so primitive that I can almost picture a 1980’s-era IBM mainframe still being used in some back office to manage the database. Fortunately, the UC Berkeley SafeTREC researchers have geo-coded the data, and made it available through a nicely designed web page. The tool not only gives details on each collision, but will even bring up the Google Streetview image of the location!
For example, here is a map generated for the bike and ped collisions in Berkeley during the year 2011. There were 108 total:
If you are a transport planner, or bike/ped advocate, I think you will find this web tool to be invaluable.