03-12-2021, 04:09 PM
(03-12-2021, 11:19 AM)Bytor Wrote:(03-11-2021, 11:52 AM)ijmorlan Wrote: It doesn’t need to be twinned all the way anyhow.
Not twinning, however, makes it logistically very difficult to attain 30 minutes heads in both directions at the same time, as #2WADGO promised.
(03-11-2021, 11:52 AM)ijmorlan Wrote: In particular, the last 1/2 of headway of any route can generally be single-tracked without imposing significant operational difficulties. For an hourly service, this means the last 30 minutes of the route. The track distance from King St. in Kitchener to Gordon St. in Guelph, where the track is doubled around the station, is less than 23km.
The Kitchener to Guelph time is 22 minutes, according to the schedule. That means if you have a train leaving Kitchener for Guelph at XX:00, the opposite direction cannot leave Guelph until XX:22, and then that means a second train cannot leave Kitchener until XX:44, which is well below the promised half-hourly peak service for #2WADGO to Kitchener. Guelph→Acton and Acton→Georgetown are 16 minute trips, which means that they can't be run at 30 minute schedules, either.
(03-11-2021, 11:52 AM)ijmorlan Wrote: So as long as the trains are scheduled so that opposing trains meet in Guelph, no double-tracking is required between here and Guelph; and for that matter the first 30 minutes the other side of Guelph could be single-tracked as well, which gets all the way to Georgetown.
It's not really the "last 1/2 of headway" that is the issue, it's the length of the length of the scheduling blocks and whether you require them to be uni- or bi-directional that is the logistical hurdle. And as shown above, it's impossible for the Kitchener→Guelph block to reach it's stated peak target for #2WADGO.
(03-11-2021, 11:52 AM)ijmorlan Wrote: I’m ignoring freight here; those would have to be slotted in as well, meaning that hourly passenger service may require double-tracking. But every 2 hours passenger service definitely does not and depending on how flexible the timing of freight activity is it might be possible to move it to lower frequency periods of time.
And every two hours is also well below the off-peak service promised by #2WADGO to Kitchener. 30 minute peak, 60 minute off-peak.
To be honest, I had forgotten that a promise of 30 minute service had been made (is that true?); I thought the promise was for hourly service, and I’m not expecting anything better than every 2 hours for quite some time.
My point was that we could have something that could reasonably be described as “all day both ways” service without twinning the track. Eventually we will definitely want twinned track all the way; the part you might be able to get away with not twinning (in Kitchener) is already twinned.
You are right that there are some complexities, but it’s still fundamentally true that the last 1/2 headway can be single-tracked because there is only one train at a time in that portion of the line. Strictly, 1/2 of (headway minus terminal time). For example, 30 minute service that takes 10 minutes at the terminal only ever sees one train at a time in the last (30 - 10) / 2 = 10 minutes of the route. Time for switches and signals to adjust will shorten the physical length of track that corresponds to a particular amount of time.
Speed of operation is also an issue; with track improvements, the time between Kitchener and Guelph or Guelph and Georgetown should each be well under 30 minutes meaning that hourly service (but ignoring freight, which is unrealistic) should be achievable without twinning. Of course the closer the schedule gets to the theoretical maximum the worse the impact of any problems, but still we’re used to ridiculously slow operation on this line so distances seem to be of greater duration than they should be.