Introduction TXDoT has available, online, detailed data regarding traffic collisions throughout the state. The data itself must be queried and downloaded manually as CSV files, but that is not too bad. I downloaded the data for Harris county from 2010 to 2018.
Database is documented at https://www.txdot.gov/inside-txdot/division/traffic/data-access.html
Access is from https://cris.txdot.gov/secure/Share
Log on and download one year at a time. The zip files will require the login password to open them.