Metro General Manager Paul J. Wiedefeld, center, listens during a congressional hearing on the transit system’s problems. (Bill O'Leary/The Washington Post)

Metro reached a milestone this month when General Manager Paul J. Wiedefeld announced a “massive effort” to address safety problems and speed up the rail system’s rehabilitation.

The thing about milestones is that there’s one every mile. And the 40-year-old Metro system has a lot of miles on it.

Wiedefeld, who took over in November, wants to accelerate the maintenance program that was accelerated five years ago.

“It is clear that the current approach is not working,” Wiedefeld said of the agency’s rebuilding effort. “More aggressive action is necessary.”

He’s right about that. So was the guy who in 2011 said: “The system wasn’t maintained the way it should be, and we have to make up for that now. That’s why we’re doing this intensive work.”

That guy, former general manager Richard Sarles, outlined his version five years ago this month. As an example, he previewed a couple of days worth of special projects that would disrupt service on the Blue, Orange and Red lines.

“During the weekend, we will replace four track switches at the Eastern Market Metrorail station and 4,700 fasteners and make repairs to the aerial structure outside the Stadium-Armory Metrorail station.”

Some of the work involved setting up a fleet of shuttle buses to get riders around a closed part of Metrorail. “I appreciate that any temporary service change is an inconvenience to riders and a concern to area businesses,” Sarles said at the time. “These critical improvements to the safety and reliability of Metrorail are absolutely necessary.”

Five years later, we’re in for an even more intensive series of track-work projects. They also are absolutely necessary — only more so, because the previous five years of disruptions have left many riders disheartened by the delays and angry over the outcome.

It seems that the aggressive program Sarles outlined in May 2011 wasn’t aggressive enough. Wiedefeld compared Metro’s previous efforts to shoveling sand out of one side of a ditch while sand poured in just as quickly from the other side.

History is not telling us his effort is futile. It does suggest we should curb our enthusiasm about the likely results.

The work crews won’t be building a new railroad. They will continue rebuilding the old railroad at a faster pace. After a year of this added turmoil, we don’t know how much safer or more reliable Metro is going to be.

The new SafeTrack Plan is not a magic formula. It targets many of the same types of track projects that have been underway for years. For example, a SafeTrack goal is to replace about 48,000 old wooden track ties in the above-ground portions of the lines with 48,000 new wooden ties.

Assuming that gets done on schedule, the work crews could fall back to a normal pace, replacing 11,000 ties a year just to avoid falling behind again.

Metro’s promise is to speed up about three years of work into about one year. But it’s basically the same sort of work that had many riders wondering afterward, “How is this better?”

Addressing the legitimate skepticism about how much track rebuilding actually got done during the past five years, Wiedefeld pledged that there will be independent reviews of the work by people reporting the results directly to him.

By extending the hours for track work and adding in weeks of single-tracking and station closings, Wiedefeld raises the stakes on the results. It won’t be enough to tell us we got our 48,000 track ties. The riders, civic leaders and business owners who spent a year reinventing the way we commute are going to expect a Metro that actually is safe and reliable.

This is not to suggest that Metro is doing the wrong thing by implementing this new program. (And it’s not as though Metro will take a vote among the riders before deciding how to proceed.) But we need to cast a cold eye on the new plan and remember what we’ve been told before.

Dr. Gridlock also appears Thursday in Local Living. Comments and questions are welcome and may be used in a column, along with the writer’s name and home community. Write Dr. Gridlock at The Washington Post, 1301 K St. NW, Washington, D.C. 20071, or ­e-mail drgridlock@washpost.com.