A Metro committee says it will be acceptable for trains to run every 30 minutes during off-peak times when maintenance or repair work is being conducted. (Jabin Botsford/FOR THE WASHINGTON POST)

Metro has redefined what it means for its trains to be “on time” when the transit agency is carrying out maintenance or repair work.

Under guidelines approved Thursday by a Metro committee, it will be acceptable for trains to run as infrequently as every 30 minutes during off-peak times and every 15 minutes during peak times when maintenance or repair work is being conducted on the line. Acceptable wait times during normal operations will be shorter but are unspecified under the rules.

The new criteria will have no direct effect on service schedules, Metro officials said, but some riders fear that by setting such low standards, Metro is taking a step toward more regimented service.

“It would be like Amtrak, right?” asked Jay Harris, 40, on a Red Line train Thursday. “You’d really have to plan ahead.”

Kathy Porter, a Metro board member from Maryland, said she thought average wait times would be a more useful measure than the maximum wait times that were proposed. “I understand what you’re trying to do,” she told the Metro staff members presenting the proposed criteria, “but I’m also worried about ‘you get what you measure.’ ”

The proposal came before Metro’s Customer Service and Operations Committee on Thursday.

Alternate board member Mary Hynes of Virginia, who sent a message to be read in her absence, said that 30 minutes is “way too long” to wait for a train.

But Tom Harrington, Metro’s director of long-range planning, insisted that he and his colleagues are “not proposing any service-level reductions.”

Another senior Metro official, Andrea Burnside, said the guidelines are a first step toward establishing a “more robust set of criteria” to rate Metro’s performance. “This is step one of the process, not the end point.”

Board member Tom Downs of the District was satisfied with the new criteria.

“If ultimately this is a tool that is useful,” he said, “this should be an active management tool. I think this has the potential to have the same kind of impact as bus guidelines.”

The committee ultimately approved the proposal and board member Mortimer Downey’s amendment that would require shorter but unspecified wait times when the Metro system is operating normally and leave the 15- and 30-minute standards to apply during repairs or maintenance.