Despite sparse communication from the MBTA that has frustrated local mayors and town managers alike, we know by now that the Orange Line is going to be closed for 30 days starting on Friday. But what, exactly, does the MBTA hope to accomplish during that time?

Since the initial joint announcement from Gov. Charlie Baker and MBTA General Manager Stephen Poftak on Aug. 3, updates from the MBTA have been few. Now, the agency has released A Rider’s Guide to Planning Ahead — a resource for alternate routes and modes of travel as well as a comprehensive primer to the repairs taking place throughout the Orange Line shutdown from Friday, Aug. 19 to Monday, Sept. 19.

Much of the work being done is to address safety concerns that have cropped up after numerous incidents on the Orange Line, including a train that caught fire with 200 passengers aboard last month, as well as to better accommodate decades-old rail infrastructure for an entirely new fleet of cars expected to be in place by the end of the year.

Among the scheduled repairs is the replacement of worn tracks along the Southwest Corridor — particularly through the Jackson Square, Back Bay, Tufts Medical Center and Haymarket stops — that have forced slow zones since 2019. Currently, going any faster than the limit of 10 mph through these areas could result in further damage to rail lines and trains.

According to the guide, 3,500 feet of tracks at Wellington Yard will be replaced, on top of the four miles of new tracks already implemented earlier this year. This year’s extensive work is the first since the station’s opening in 1975.

The Orange Line’s analog signal system will become fully digital, and new signaling infrastructure will be installed at the Malden Center and Oak Grove stations.

New power substations will be implemented at Oak Grove, Malden Center, Wellington, and Sullivan Square. Their facilities will also be upgraded “with new structural, mechanical, plumbing, and electrical repairs” to accommodate 152 new trains, according to the MBTA.

In addition, new crossovers, tracks, ties and ballasts will be installed to meet the Federal Transit Authority’s State of Good Repair guidelines. The agency had previously criticized the T and stated that its current operating conditions endangered staff and riders.

Alternative travel options during the closure — including the MBTA buses, Yankee Line shuttles, Commuter Rail, and free Bluebikes — are included in the guide as well.

The guide also contains information about the upcoming four-week Green Line extension closure, which will coincide with the Orange Line shutdown and likely cause travel confusion and delays among riders.

Baker and Poftak have justified the temporary closures by saying that they are more efficient than the five or more years that would be required to complete the repairs through normal maintenance procedures, which rely on mostly nighttime and weekend work.