it appears u happen to be taking a train during morning peak
hours. train bucking is common during peak hours, where headways
are as short as 1.5-2 mins (time required to travel a typical
station's distance). all these delays are part & parcel of a
non-fully-automated train operating system with short
train-to-train distances. do remember that ang mo kio station, jus
after yio chu kang station, is also a very busy with trains
changing tracks a lot during evening peak hours as they turn in
& out of bishan depot, or move to the middle train when they
terminate at amk.
from my observation 5mins between same phase. let's take this phase
as train departing. train departs yio chu kang at 0th min, enters
at khatib at 4th min 15th sec, doors open at 4th 35sec, close &
depart at 5th min. taking a new black KNS train and observing the
time display (especially on-minute changes) will reveal so.
smrt trains move with predictable movements, like it will start
accelerating here, decelerate here etc. these are strictly followed
by every PTO to ensure the predefined time schedule (in this case
5mins) is met. during heavy-load but not peak hours (like after
evening peak all the way up to 11pm) trains will move faster but
this is compensated by the fact that they will stop longer at each
stop due to heavier movements thus it's still the same travelling
time in the end. trains can always move on to the fast mode to
catch up if it is behind schedule.
in my many trips down from yio chu kang northbound, i have not
experience a single hiccup, even during evening peak hours, worse
than a 3-min wait on a train parked at yishun mrt NB, due to an
impatient PTO driving from yishun's overlay track to the sountbound
track before the train at yishun SB platform moved out, causing an
ATP (Automatic Train Protection) panic & stalling all trains in
that sector. any train that stopped along the tracks on the KTB-YCK
sector moved off within a minute.
for southbound KTB to YCK (all best detected at 4th door),
normal: trains accelerate to yishun stadium, cruise until buillion
park & accelerate uphill, cruises, brakes immediately at the
point of teething sounds just after castle green, cruise until 3rd
door jus enters the station before braking normally to stop.
fast: trains accelerate to yishun avenue 1, brake twice briefly at
seletar intake station, accelerate about 3 times briefly on the way
to SLE, accelerate way before uphill section until halfway up, then
accelerate again until near end of bend, cruises or may accelerate
one time more, brakes immediately at the point of teething sounds
just after castle green, cruise until 3rd door jus enters the
station before braking normally to stop.
for northbound YCK to KTB,
normal: trains accelerate till end of bend outside station, cruise
at low speed, accelerate jus before castle green until near yio chu
kang rd, cruise all the way to seletar intake station, accelerate
briefly along the leftward bend, then accelerate from yishun ave 2
to after yishun ave 1, cruise, brakes when the front of train is
about 20m away from station (4th door about a 2 seconds after it
left the parallel).
fast: trains accelerate till end of bend outside station, cruise at
low speed, accelerate jus before castle green until near yio chu
kang rd, accelerate again along until lentor intake station, brake
briefly once on the way downhill, then brake twice (or sometimes
thrice) briefly under SLE flyover, accelerate about 3 times upon
reaching small bridge leading to on-land rail all the way to the
end of on-land rail, accelerate about 3secs after reaching viaduct
from on-land rail until seletar bridge, accelerate along the
leftward bend from after lentor intake station to yishun ave 2,
then accelerate from yishun ave 2 to the S-bend reaching yishun ave
2, accelerate a few seconds along the straight rail along yishun
ave 2, brakes when the front of train is about 65m away from
station (4th door straight after it left the parallel).
