(Note correction at the bottom of this post)

The newly minted TTC commissioners will have their first meeting on Wednesday, December 13, and on their plate is a decision that may significantly disrupt service for riders over six weekends starting this February, but which may open the fabled Lower Bay station to public view for the first time in forty years.

Commissioners will consider this report which looks at diverting Bloor-Danforth trains through Lower Bay station and into Museum station through the wye, in order to allow construction crews to make necessary major structural repairs to the tunnel roof between Bay and St. George stations.

The report suggests that the Bloor-Danforth subway could be split in two every Saturday and Sunday from February 18 to March 31, 2007:

Service will be provided between Kipling Station and Museum Station, and between Kennedy Station and Museum Station. Customers making a through-journey between the east and west portions of the 2 Bloor-Danforth Subway will have to transfer at Museum Station, which has a centre platform and thus allows easy cross-platform transfers. There will be no change to the route of the 1 Yonge-University-Spadina Subway.

Bay station would be closed during this diversion, with passengers expected to access Bloor-Yonge station via the Cumberland Terrace mall. The lower platforms of St. George station would also be closed. Service on both the Yonge-University-Spadina and Bloor-Danforth lines would be reduced from four minute intervals to six so as to leave enough time for both lines to use the tracks between St. George and Museum stations.

It is important to note that this is a decision that still has to be taken, and the details can still change. The wording in the report leaves some confusion as to how the diversion could be handled. The most convenient option would be to route Kipling-Museum trains through the wye, past the southbound platform on the upper level of St. George, through the crossover east of St. George and south down the northbound tunnels to terminate at Museum station. There, trains could change ends and use the wye to access Lower Bay station and return to their route at Yonge station. Trains from Kennedy could follow the reverse route, coming out of the wye at the southbound platform of Museum station, changing ends and using the crossover at St. George to access the northbound platform and resume the westbound route. However, this arrangement would not result in trains from Kipling “terminating” at Museum station.

Alternately, Bloor-Danforth trains could use the pocket track between Osgoode and St. Andrew station to change ends, out of the way of Yonge-University-Spadina trains. This makes for less “wrong way” operation between Museum and St. George. Trains would operate empty and express between Museum and Osgoode.

Another possibility could be that trains from Kipling and Kennedy could be routed south on University, to serve the University-Spadina subway up to Finch, restoring the interlining arrangement that operated for the first few months after the Bloor-Danforth subway originally opened, and maintaining more normal service frequencies on the Yonge-University subway between Museum and Finch. This and the previous option would require passengers making through trips between the western and eastern sections of the Bloor-Danforth subway to change trains at Museum.

Further details will likely come to light after the December 13 meeting.

Other reports to consider include spending up to $49 million next year to pave the way for the Spadina subway extension to York University. Although funding for this project has not been confirmed, this money may have to be spent now in order to save costs down the road (link).

(Update: Saturday, 2:03 p.m.): A clarification has been issued. Sources suggest that trains from Kennedy will deadhead between Museum and the Osgoode pocket track while trains from Kipling will deadhead between Museum and the St Andrew-Union pocket track. The use of both pocket tracks will give these trains more time to change ends and return to service.

Some consideration was given to operating these trains up the University-Yonge subway to Finch, but this was dropped due to signalling issues with the older models that operate on the Bloor-Danforth line, and because this would increase the number of operators required to provide the service.

This may change on the day, as required, and it may change between now and when operations begin, so stay tuned.

I’ve received a correction to a number of inaccuracies from this post, thanks to readers in the know. First of all, commissioners won’t have to approve this arrangement, as it is a temporary service change. The report offered to the commissioners is to keep the commission informed of what is coming, and not a request for approval, as it would be for a permanent service alteration.

The operational arrangement of the diversion has been confirmed as that specified by the Saturday update. Trains from Kipling and Kennedy will head through the wye via the southbound University tracks to the southbound Museum platform. Trains will then go out of service and head south on University to turn back at either the Osgoode or St. Andrew-Union storage tracks, picking up passengers from the northbound platform of Museum station and proceeding through the wye back onto the Bloor-Danforth line and on to their destinations.

Either way, it should make for an interesting six weekends, and you can expect to see a few railfans come out to catch this rare glimpse of Lower Bay from the windows of revenue trains (even if the trains won’t stop at Lower Bay).