Williams was named to the interim post on Thursday by MTA chairman H. Dale Hemmerdinger. Friday was the last day on the job for Sander, who agreed to resign after the State Legislature's long-delayed passage of a bill to address the cash-strapped agency's growing deficits.

"This is a time of transition at the MTA, but it is critical that we continue to serve our customers without missing a beat," Hemmerdinger says in a statement. "Helena Williams is doing a terrific job at the Long Island Rail Road and will be an excellent steward for the entire transit system until a new chairman and CEO is appointed."

GlobeSt.com reported in early May that Gov. David Paterson is revamping the MTA's governance, combining the responsibilities of executive director/CEO and chairman into one job. Hemmerdinger, president of Alco Properties and Management, is himself leaving his unpaid position as MTA chairman next month to allow the governor to start with a clean slate.