Bruce Jenner -- Full Steam Ahead On Sex Change Docuseries

Bruce Jenner's upcoming docuseries chronicling his change from a man to a woman is going full bore ... despite Saturday's fatal car crash.

Production sources say there has been absolutely no move to slow down the shooting, editing or airing of the special, which will begin airing as early as May. We're told Bruce has given no indication he's had a change of heart.

We've learned the show is being produced by Bunim/Murray Productions, which also produces "Keeping Up with the Kardashians." The company has produced a slew of reality shows, including "The Real World."

As we reported ... the L.A. County Sheriff's Dept. is investigating the crash. Law enforcement sources tell TMZ they believe Bruce was following too closely behind the Lexus he hit, sending the car into oncoming traffic. The driver was killed after colliding with a Hummer.

Bruce faces an almost certain civil lawsuit and could be prosecuted if the D.A. believes he was indeed following too closely, but as we reported such prosecutions are "very rare."