As the MBTA seeks to accelerate its efforts to rebuild the city's transit system, its riders are preparing for some disruptive times ahead.

The MBTA began instituting weekend-long "diversions" in 2019 as passengers were diverted to shuttle buses while tracks, signals and power systems were replaced and several stations upgraded. Although it did inconvenience riders, it gave workers enough time to make more progress. The results were so encouraging that the T decided to expand the effort to not just weekends, but whole weeks and, in some cases, entire months.

A panel of transit experts — including Tom Nally, planning director at A Better City, a group of business leaders working to bolster the region's economic health, and Ari Ofsevit, a Boston Program senior associate at the Institute for Transportation and Development Policy — will discuss these issues on March 4 at the Boston Public Library.

The T said that in 2020 there will be more weekend "diversions" on all rapid transit and several Commuter Rail lines.In addition to more weekend diversions on the Green Line, there will be two month-long shutdowns: the C Branch in July and the E branch in August.

T officials said all of this means projects will be able to be completed eight years sooner than originally planned.

In addition, there will be an 11 month suspension of all Green Line service between North Station and Lechmere beginning in May 2020 as the Lechmere Viaduct is rebuilt. Weekend diversions can also be expected on the Orange Line, the Silver Line and, for the first time, the Blue Line.

On the Commuter Rail there will be weekend diversions on the Franklin Line. In March, there is a planned suspension of weekend train service between Worcester and South station — in addition to a massive project getting underway to rebuild part of South Station and connect it to the bus terminal.

The MBTA advised that commuters to allow an extra 10 to 15 minutes beginning in July as the South Station work shifts into high gear.

Add to that more work at Back Bay and North Stations. Transportation Secretary Stephanie Pollack admitted all of thew work — in addition to projects at Back Bay and North Stations — is a lot for commuters to deal with.

"Right now the most disruptive thing that happens on the T is the unplanned shutdown," she said. "The reason we are asking our customers to tolerate these planned disruptions to their commute is to reduce and eventually eliminate the unplanned disruptions that have been the biggest complaint of our customers."