SEPTA is performing maintenance on the Market-Frankford Line in Center City this weekend, and will be running shuttle buses from 11th Street to 30th street all day Saturday and Sunday while through service is suspended. Additionally, single tracking will occur 8th St-15th St after 22:00 Friday, and 8th St-13th St Saturday and Sunday. See the Service Advisory on septa.org for all the details.
While I approve of SEPTA taking proactive measures to achive and maintain a state of good repair, and a full weekend shutdown will give plenty of time for repairs too complex to be done overnight, I have to object to the use of shuttle buses to bridge the gap between the 69th-30th and FTC-13th services. The Market St corridor is the main commercial axis of the City of Philadelphia, and is served by three rail transit modes: the MFL, the Subway-Surface trolleys, and the RRD Center City tunnel. On weekdays, each serves a different travel market and runs at capacity at rush hour, with each complementing the other two. On the weekend, with none of the three running anywhere near capacity, it should be possible to compensate for the loss of the one solely with the other two, without resort to busing.
First, the Subway-Surface trolleys will be running through the tunnel full-time, forgoing their usual 22:00 Sunday shutdown and diversion to 40th/Market. This is especially helpful to Westbound passengers coming from the Frankford El/Old City side, since 13th St will be open as a discharge-only stop for them, allowing a normal transfer to Juniper St Loop, and a transfer back to the West Market end at 30th St. Eastbound passengers will not be able to board at 13th St unless they require an elevator for ADA access, to minimize the time required to turn trains, but those West Market passengers bound for Center City West and the Broad Street Line transfer at 15th St will be able to access those points, and also retain the option of walking 2.5 blocks from Juniper to 11th Streets. If SEPTA fears overcrowding on the trolleys’ light weekend schedules, extras can be run in the tunnel only, turning back at the loop at 40th St Portal.
Second, SEPTA can accommodate local passengers on Regional Rail between 30th Street and Market East. Market East Station is immediately adjacent to 11th St Station on the MFL, while 30th Street and 30th Street lie on opposite sides of their namesake without an open connection beyond the crosswalk. There is, with extremely rare exception, no such thing as a crowded weekend train on the RRD; and while there is a fare for within-Center-City trips listed in the tariff, and the paranoid fear of losing those fares is a driving force behind SEPTA’s plan to install faregates at the Center City stations, it remains true that standard procedures mean that no fare is ever collected between the three Center City stations. SEPTA can “suspend” fare collection between 30th and Market East during the MFL shutdown by making an announcement to the effect and then not lifting a finger. The only potential downside is that the high passenger count might cause delays, especially on slot-sensitive trains like Trenton trains. This wouldn’t be a problem on an all-Silverliner V fleet, where three doors are available at high-platform stops, but the majority of the fleet, especially on weekends, is Silverliner IVs. On weekend trains that often only have two cars, this means that both cars are often restricted to a single end-door; at high volumes, this could produce delays even to the excessively padded schedules. An alternative would be to use the spare track capacity of the tunnel to run dedicated “El Shutdown Special” trains back and forth between Powelton and Roberts Yards, directing local passengers to those trains (and making sure they run with Silverliner Vs!) and safekeeping the on-time performance of SEPTA’s regular weekend schedule. Some wily passengers would figure out that they could just use any train, but only just as many as will have figured that out anyway.
As always, you should not commit fare evasion, but this weekend, as any weekend, all Transpasses, Trailpasses, and Cross County Passes are good Anywhere on the SEPTA system, including on the RRD between Center City stations. Safe travels!
Sic Transit Philadelphia 
I’m slightly confused about verb tenses — is the paragraph beginning with “First” actual or hypothetical? Is this something SEPTA is already doing (for the reasons you state? for other reasons?) or something they should be doing?
Busstituting the MFL for the 30th-69th corridor makes sense. Busstituting in Center City traffic, where there are numerous redundant rail lines, is just odd. The only advantage of buses is that bus-riders seem to have evolved (out of necessity!) a nearly telepathic ability to figure out whether their buses are on detour and where they will be making stops, in the absence of effective communication from SEPTA. So maybe SEPTA is trying to take advantage of this trait!