in the event of rain?

zhlow SG

was taking a west bound train today when not long after the train left bouna vista it encountered heavy rain with strong winds at about 2.25pm. what happen was that the train suddenly brake to a halt...can also hear the sound of gas releasing from the underside of the train ( emergency brake?? ). what could have happen? any of the train enthusiaist can enlighten me?

after stopping for sometime the train carried on moving and approached dover station.i think the train was running in cm mode, cos the braking was rather jerky before it came to a halt. however the doors was unable to be opened and the train had to move on to clementi. passengers dropping at dover had to drop off at clementi instead. IS this a case of too much over-run that the train doors cant open?

TIB1224Y SG

I think the procedure is to move the mode selector to CM mode and then the train will stop due to the power selector at B4, next, the train moves again when the TO selects it to P3 and so on... Rain wise P3 not lah, maybe P2.
Power levels 3, brake levels 4 plus emergency.
Overrun must see if its past the 'Set Back Limit'
But generally I feel that local TO are not good at CM/manual passenger ops... Try BVE trainsim and you will know... Can you attempt a 0.0 metre accuracy? Not easy...

Oceane SG

Poor visibility may be a cause. Anyway, the track leading to Dover has a decline just before reaching Dover; the TO may have to slow down to approach the slip.

Sound of gas releasing is due to hydraulic emergency brakes.

Train doors can still open if train over-run, but TO has to try to reverse train. Doing so will affect train schedules.

Vigelic SG

lol do they sometimes release sand? weird sound i heard once when it was travelling in rain.. my fren said releasing sand..

what does CM stand for?

and i agree that our TO not accurate one -.-

TIB1224Y SG

Hmm cause the training is not as comprehensive as some other systems?
This is metro afterall...
Not train, so quite normal lah...

^tamago^ SG

Sand increases friction. But they must be fine enough, if not derail. Laughing

CM = Coded Manual. Drive under supervision of speed codes. Nowadays only used when it is raining, or if special attention is required such that the driver has to drive the train himself.

Most times, the train is on Automatic Mode (AM). Fully operated by computer while driver looks on and make sure it's in order. Operates the doors as well at each station.

^tamago^ SG

our system cannot suga-suga reverse or change direction of travel de, cos will trigger ATP. Laughing

set back limits is dunno for what but doors can only be opened at stations within the limits where possible. if not the system wun let the doors open.

^tamago^ SG

dooo…~

Manager433 SG

Laughing

The sound of sudden air releasing is actually air dump out of the dump valve. This is to similar to a car with ABS system. Got it?

^tamago^ SG

Expert come in liow. Thank you. Razz Embarassed Laughing

Reading wiki now....

Scania SG

Hydraulic mechanisms don't create air sounds, they use liquid.

The_Bus_Guide SG

From what I understand, the "Set Back Limit" is the maximum distance from the end of the platform where the train is allowed to reverse. It is set at exactly 6 car lengths. If the driving cab passed this limit, indicated by a sign with 2 vertical black lines, it means the last car of the train had passed the platform edge. This is like the "Point of No Return" and the train must proceed to the next station.

zhlow SG

icic. now i understand how everything works. i used to think that the gas releasing sound was the spraying of sand cos in some diesel locomotives, sand is sprayed on the wheels to increase traction.

however, why isit that in rainy condition then CM mode have to be employed? is it due to the fact that due to wet rails hence the computer might be unable to correctly determine the power and braking power needed for the train?

i am also very interested in how those walk through connectors in between carriages work. anione can provide details? cheers!

The_Bus_Guide SG

There is only one brake pipe for the whole train. In an emergency application, the air in the brake pipe is cut-off immediately, exerting a 100% brake application.

^tamago^ SG

our system work quite differently wor. Surprised

^tamago^ SG

yes, and as a safety measure. because the deceleration can vary by a lot in slippery conditions and there is a possibility of overshooting the station on AM, the driver has to drive under CM.

i used to think so too, until i read up on how e-brake on trains work. Surprised but on older rail systems, particularly non-metro's, sand is still used.

The_Bus_Guide SG

.............

nenepokey SG

talking abt this, there's once i took a train to AMK to transfer a bus to sch. the train slowly entered the stationof AMK slowly, and suddenly giving a jerk, and stopped. many people had almost fell. after the powerful jerk, it stopped for another minute or so, before opening the doors. the TO must have applied the E-brake. could he be sleeping at that pt in time? then suddenly wake up to find the train almost exceeded the limit?

TIB1224Y SG

Its impossible for the TO to fall asleep in our systems, for there is a 'dead man switch' on the control stick whereby constant pressure is necessary to operate the train using the stick in CM and manual modes. Release the the brakes apply.

The situation may be that the TO misjudged distance, a very common occurance here because TOs are not trained specifically to operate the train manually. When he finds that the distance is closing up, even when the speed is low, there is a tendancy to apply hard brakes to stop the train immediately, which leads to those situations.

Remedy? Do not panic, apply brakes slowly and stay at that brake level, do not adjust to higher levels. BVE program trains excellent TOs and it should be included in the course. Get 40 x 0.0metres and graduate.

EXCO SG

Set Back Limits are anywhere between half to one car length only, depending on the station. Meaning to say if the train overshoots by one or half a car, it will not be allowed to reverse due to timetabling and ATP.

The TO will need to comms back to report the overshoot and obtain permission to go into CM, which will allow him to reverse. In time constraints, this might not be approved and the train will instead hold at the overshoot position before continuing on.