Make simple plot of car incidents using https://data.seattle.gov/Public-Safety/Seattle-Police-Department-911-Incident-Response/3k2p-39jp Seattle Police Department 911 Incident response data.  Next find nearest compkey road segment and make map that scales thickness with incident quantity.  Also could incorporate car counts and do incidents normalized for vehicles, or incidents vs. vehicle quantity.
Need much faster method to link crashes to nearest compkey