Here are some of the reasons why you won't get to see a
consistent 2 mins per train frequency:
1. We are currently facing "train shortage".
2. SMRT & LTA prefers to have the system to perform at it's
optimum (24tph), rather than at it's maximum (28~30tph).
3. Normal Mode and Fast Mode Exist in Auto Mode. A train coasting @
40~60km/h is not utilizing every seconds. When accumulated enough
over time, it will have sufficient headway to allows an
extra train to be placed into the system for revenue service.
4. Inefficient schedule. Trains are given too much time to travel
in between stations. (See point 4)
5. Schedule of train's frequencies are inconsistent.
Train C <--5 mins frequency--> Train B <--2 mins
frequency--> Train A
6. During CM, performance of system decrease as TO are not
trained well enough to operate a train as well as a computer.
7. Automatic system has it's constraints and because of these
constraints, multiple redundant failsafe mechanism are required to
prevent an accident/incident from occuring. These failsafe
mechanism decreases the maximum performance acheivable when
compared to a system where trains are driven manually.
Train congestion, is acceptable as long as there is no more than
one train stopped completely waiting for the front train to clear.
This problem can be minimized by enforcing effective &
efficient scheduling of train as well as "dwell time abuse".
When the system are pushed to it's maximum:
North-South/East-West Line: 45~70 seconds (6-car formation)
(ATC-4)
Keikyu: 0~30 seconds (4,6,8, 12-car formation) (C-ATS)
Keio: 15~24 seconds (10-car formation) (ATS-S)
Yamanote: 25~30 seconds (11-car formation) (D-ATC)
Frequencies given above are obtained by having the
timer:
- Start: The moment the train starts to move off
- Stop: Front-end of the train behind touches the back end of the
platform
As different train system has different no.-of-car/train length,
it's unfair to determine frequency by:
- Timer start when train totally cleared station, timer stop when
train behind made a complete stop in station
- Timer start when the moment the train starts to moves off, timer
stop when train behind made a complete stop in station
- Timer start when train has totally cleared the station, timer
stop when front end of the train touches the back end of the
platform
If train shortage, why still got train in depot?
I think is TO shortage since not many people want to be TO.
6. CM mode should be used only when necessary.
