After Metro’s new six-month schedule for major track work was published last month, readers noted that two of the projects have been appearing on the service disruption schedules for a long time. They are the rehabilitation of the platforms at Minnesota Avenue and at Deanwood, and the construction of a test track between College Park and Greenbelt for the new Metrorail cars.

I asked Metro Assistant General Manager Rodrigo Bitar about them. He is in charge of transit infrastructure and engineering services.

The platform rehabilitation at the two stations in the District is really the rebuilding of platforms, he said. This is much more than the replacement of the terra-cotta-colored tiles that wear out and crumble. It turned out that the concrete supports for the two platforms on the east side of the Orange Line needed reconstruction. If workers had replaced only the tiles, Bitar said, they would have cracked and crumbled as the concrete beneath them deteriorated further.

Project managers didn’t realize the extent of the foundation problem until they had uncovered some of the surface material, he said. They had to design a new support system, demolish some of the old structure and then rebuild it. And the crews must rebuild while maintaining service. This is an issue with road and bridge projects as well as with transit work. Jobs would go a lot faster if the road or bridge or rail station could be shut completely for a lengthy period of time.

But engineers find that impossible to arrange on major commuter routes. That applies to huge projects, such as the rebuilding of the Woodrow Wilson Bridge, and to relatively small ones, such as the rehabilitation of the New Hampshire Avenue bridge over Sligo Creek in Takoma Park.

One of the new rail cars is seen at the Kawasaki Rail Car plant in Lincoln, Neb. ( Washington Metropolitan Area Transit Authority)

A road or bridge reconstruction is done lane by lane over a long time, and a transit project is done section by section.

So the platform projects have made frequent appearances on Metro’s weekend work schedule and will continue to do so. In some cases, the work zone is limited. Orange Line trains share one track to get around it. To prevent trains from bunching up while awaiting their turn on the open track, Metro puts more space between the trains than on a normal weekend.

In other cases, the work is more extensive, and the stations are closed.

Whenever Metro managers schedule work on the platforms, they attempt to coordinate it with other projects along the Orange Line, such as replacements of track circuits, switches, rails and rail ties.

“It’s much more complicated to rehabilitate than to build from scratch,” Metro spokeswoman Caroline Laurin said.

The Deanwood platform rehabilitation project is scheduled to be done by October, Laurin said. Most of the structural rehabilitation is complete, but the architectural work — including the tile, granite edge, paint and lights — depends on good weather. That work won’t resume till spring.

Minnesota Avenue’s is scheduled to be finished by October 2015. The structural work is about half done. After that’s complete, the architectural rehabilitation is scheduled to begin in spring 2015.

Test track

Construction of the test track for Metro’s 7000 series rail cars also involves a sharing issue, but this one is with CSX freight rail operations in that same area, between College Park and Greenbelt. The target for completing the Metro test track is this fall, Bitar said. But this schedule should not delay the new rail car program.

Four new cars have arrived from the manufacturer, Kawasaki Rail Car. They will undergo months of testing to make sure their systems are compatible with the rest of Metrorail. (These cars are distinctly different from previous generations.) If track testing is necessary before the new track is completed, it can be done overnight when the rail system is closed to passengers, Bitar said.

But it’s only when Metro is satisfied with the performance of this initial batch of cars that the plant will get the go-ahead to send more. There won’t be a bunch of new cars waiting around in a yard for testing while the track is under construction.

With this construction project along the Green Line, Metro has used a variety of approaches to reducing the effect on weekend riders. Sometimes it uses the single-tracking technique and spreads out the gaps between trains.

On other weekends, Green Line trains don’t operate between College Park and Greenbelt. The next of these weekend shutdowns of the Greenbelt station is scheduled for March 15-16.

One frequent weekend project of last year that isn’t on this year’s list for major track work: the weekend disruptions on the west side of the Orange Line to establish the tie-in with the new Silver Line. We’re done with those.