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West of the Sheppard station, there is an incredibly long tail track [aronund 800m long] used to store up to two or probably three spare trains. Under normal service, this line always have four trains running, and frequently I saw another train parked on either side of the tailtracks. East of Don Mills station, there are a pair of two very short tailtracks, which are probably never used unless they are used to store work cars. I have a few questions regarding the usage of these tailtracks.

I am kinda curious as the Sheppard tail tracks is the only dead-end tracks that contain multiple interlock signals within it; furthermore these interlock signals can change from double red to something like yellow over green, so trains heading into these tail tracks don't need to be called on to access it. More interestingly, trains must use the tail track to go back to the Yonge line, maybe for maintenance over the Davisville or Wilson yards. Each day I see this station I saw a different arrangement of trains parked on these tail tracks; it likely implies that these tracks are used regularly each day, possibly during regular times like maybe every midnight or so.

On the other hand, the Don Mills tail tracks are controlled by interlock signals that are always double-red, but with a call-on signal. The tail tracks are very short, implying that they might only be used to store non-revenue vehicles like work vehicles and garbage trains. I never saw such usage ever during my time I took the TTC.

It can be said that the Sheppard line is incomplete and that there has been multiple failed proposals to extend the lines both ways. This way, 6-car trains can be used and the removable walls can be tore down. Attached is the layout and all the observed signals I saw around the Sheppard-Yonge subway station; I still have trouble clearly observing the link that leads trains from the Sheppard line to the Yonge line deep within the tailtracks, and understanding which signals are used to lead northbound Yonge trains into the Sheppard line.

How often are the Sheppard tailtracks used? Do trains enter the tailtrack at scheduled times or randomly depending on whatever maintenance is needed? How often are the Don Mills tailtrack used?

SheppardTailTrack.GIF

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There are 6 trainsets that have been configured to operate on the Sheppard Line, 5 of which are stored on the line overnight, primarily in the tailtracks. (When the line was opened, 3 were stored in the tailtracks and the other two on the platforms at Sheppard-Yonge. I don't know if this is still the case.) And yes, 4 are used for service on a daily basis. The idea is that if one of the 4 trains needs to be replaced for any reason, there is a spare nearby that is ready to insert into the rotation with a minimum amount of fuss and hassle.

 

Your schematic of the tailtracks is not correct. Refer to this one: subway-5110-20.gif

 

As for the signalling within the trailtracks, I've not found any diagrams that show the signalling layouts in the tailtracks.

 

Dan

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On ‎7‎/‎29‎/‎2019 at 2:04 AM, --Mulliganaceous-- said:

 

How often are the Sheppard tailtracks used? Do trains enter the tailtrack at scheduled times or randomly depending on whatever maintenance is needed? How often are the Don Mills tailtrack used?

SheppardTailTrack.GIF

The cut-and-cover tunnel extends west to Welbeck Road. However, track is laid all the way to Welbeck only in the westbound direction. The eastbound tail track gradually curves and merges with the westbound wye (connecting with the Yonge Line) at switch S196 and then joins the westbound tailtrack at switch S197. (refer to the attached PDF's that document both signal and track installation). Beyond S196, the eastbound tunnel is empty (i.e. there is no track laid), but my understanding is that there is track foundation all the way to Welbeck. Beyond S197, the westbound tail track extends enough to fit at least an eight-car train, which is necessary to allow reversal into the westbound wye if a train becomes disabled and needs towing to Davisville or Wilson. I have not seen diagrams of the signal configuration either, but my understanding is that all signaling in the tailtracks is grade-timed.

The tail tracks are used whenever change-offs are needed, which is unpredictable, although they generally happen outside of rush hour. Before the introduction of OPTO, when the T1's were running and no spares were stored on the line itself, it was not unusual to have some sets in daily, continuous service for 27-28 days before being changed-off.

Since all the fleet required for service is stored overnight at Sheppard-Yonge, a team of mechanics does go up there every night. Regarding storage, the situation is as follows:

between Nov 2002 and Oct 2003, five trains were stored overnight at Sheppard-Yonge (4 needed for service + 1 spare at all times).

in Oct 2003, a change was made, in that they no longer stored a spare in the tail tracks at all times. This made sense, since Davisville was only 10 minutes away and provided all the change-offs as needed.

In Oct 2016 when OPTO was introduced, and probably because of the service disruptions that occurred regularly in the first few months following the change, they reverted to having one spare train in the tail tracks at all times. This remained the case even after operations normalized, probably in connection with the loss of storage space at Davisville during the carhouse expansion project. More recently, if all six four-car trains are available and none is undergoing maintenance at Wilson and Davisville, they keep both spares in the tail tracks at Sheppard-Yonge.

The tail tracks at Don Mills are so short because when the line was being built, the MTO refused to allow tunneling under Highway 404. This leads to somewhat degraded operation, since the blind trips are active at all times, so entering the station has to be done at lower speeds. Refer to the attached PDF's for more info on signal and track installation on Sheppard.

 

Signal Installation.pdf Track Installation.pdf

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