DENVER -- The woman who managed the Regional Transportation District's FasTracks expansion program is leaving for a job in private industry.

Liz Rao, who has been with RTD for 13 years, said Monday she will become national transit development director for the engineering and design firm HNTB Corp. on Sept. 26.

Rao says the job is a promotion and she will become a vice-president of the private company.

The price tag for the project has ballooned to $7.9 billion from $4.9 billion because of fuel and materials costs.

"We do have challenges with FasTracks, but I'm not leaving because of that," she told the Rocky Mountain News.

The 12-year plan would expand bus service and add 119 miles of passenger rail service.