The Department of Transportation still needs to improve its administration of a key grant program, says the Government Accountability Office.

GAO said that while the department has made improvements in the $4 billion TIGER program, it should add more detail to the guidelines it uses to choose recipients of the grants.

Under TIGER (Transportation Investment Generating Economic Recovery), DOT solicits applications from states for grants and awards the money in a competitive process designed to focus resources where they are most needed.

GAO monitors the process and last May told the department it needs to do a better job of explaining why it awarded grants to applications that had lower technical ratings.

The department revised its guidelines as GAO suggested but they still lack detail, the watchdog agency said.

This is not necessarily the final word, however. GAO noted that its analysis came out as the department was still in the process of evaluating its most recent round of grants, and said it will review those grants to see if the department has improved its approach.

GAO recommended that the department develop clear links between performance measures and its goals for the grants. The department agreed to do so.

The GAO review had been requested by Sen. David Vitter, R-La., the ranking member of the Senate Committee on Environment and Public Works.