Chief Executive Officer Roelof Van Ark announced his resignation at the High Speed Rail Authority's Board meeting in Los Angeles. He was named to the job in 2010 - news reports say he cited personal reasons for leaving.
Van Ark oversaw the release of a new updated business plan, which showed the cost of the project had increased to nearly 100-billion dollars.
In another shakeup, board Chairman Tom Umberg announced he'll nominate Governor Jerry Brown's appointee, Dan Richard to take his own place.
Brown has remained a staunch supporter of high speed rail. However, many lawmakers have been questioning the ballooning cost of the project as well as a decision to begin construction in the Central Valley, instead of larger population centers. A recent survey showed voters have growing concerns about the project.