Some questions interested to know

Chunghong2004 SG

Curious about some questions, hope someone knows the answers

Q1. How does the train behind a train sense the distance and active brake to stop about 1 train length?

Q2. When does the train applies emergency brake automatically? Sometime in heavy rain? Approach station at high speed?

Q3. Sometime when the train stop for too long, or the doors opens for a certain amount of time, i can hear a continuous beep from the driver cabin at times. The beep stops only when the driver closes the door. What is the beep for?

Q4. Who manages the change of signal light from red to white? Automatic?

Q5. Who change the direction of switch on the track at jurong east interchange towards marine bay? Automatic?

Q5. During emergency brake, we often hear train giving out some ?gases and knocking sounds. What is that for?

Q6. What training must the driver goes before becoming a train driver?

Q7. How does the station knows train will be arriving in X mins? Are there sensors 0n the track?

Q8. Noticed that a blue colour box (at night it will shine a blue colour light) beside the track every 400m or so. What is that for?

Q9. Why is there stones on a levelled track but not in underground track?

...

sni1996 SG

Curious about some questions, hope someone knows the answers

Q1. How does the train behind a train sense the distance and active brake to stop about 1 train length?

Q2. When does the train applies emergency brake automatically? Sometime in heavy rain? Approach station at high speed?

Q3. Sometime when the train stop for too long, or the doors opens for a certain amount of time, i can hear a continuous beep from the driver cabin at times. The beep stops only when the driver closes the door. What is the beep for?

Q4. Who manages the change of signal light from red to white? Automatic?

Q5. Who change the direction of switch on the track at jurong east interchange towards marine bay? Automatic?

Q5. During emergency brake, we often hear train giving out some ?gases and knocking sounds. What is that for?

Q6. What training must the driver goes before becoming a train driver?

Q7. How does the station knows train will be arriving in X mins? Are there sensors 0n the track?

Q8. Noticed that a blue colour box (at night it will shine a blue colour light) beside the track every 400m or so. What is that for?

Q9. Why is there stones on a levelled track but not in underground track?

...

Please direct your questions to this thread :http://sgforums.com/forums/2080/topics/408388

joeyfjj SG

Curious about some questions, hope someone knows the answers

Q1. How does the train behind a train sense the distance and active brake to stop about 1 train length?

Q2. When does the train applies emergency brake automatically? Sometime in heavy rain? Approach station at high speed?

Q3. Sometime when the train stop for too long, or the doors opens for a certain amount of time, i can hear a continuous beep from the driver cabin at times. The beep stops only when the driver closes the door. What is the beep for?

Q4. Who manages the change of signal light from red to white? Automatic?

Q5. Who change the direction of switch on the track at jurong east interchange towards marine bay? Automatic?

Q5. During emergency brake, we often hear train giving out some ?gases and knocking sounds. What is that for?

Q6. What training must the driver goes before becoming a train driver?

Q7. How does the station knows train will be arriving in X mins? Are there sensors 0n the track?

Q8. Noticed that a blue colour box (at night it will shine a blue colour light) beside the track every 400m or so. What is that for?

Q9. Why is there stones on a levelled track but not in underground track?

...

Q1. How does the train behind a train sense the distance and active brake to stop about 1 train length? It's a system called ATP where a continuous stream of information is sent to and from the train. The track is separated into "blocks" of varying length, marked by the following sign.

The train will receive via the ATP appropriate Limit/Target speeds, where Limit is the speed the train can travel up to, while Target is the speed the train must target for as the train approaches the next block. The Limit/Target speed pair will take into account preceding trains, and through varying the target speed, will stop the train before the preceding train.

For more information refer to this article of the LU Central Line's ATP system, which is based on the NS/EWL system.

Q2. When does the train applies emergency brake automatically? Sometime in heavy rain? Approach station at high speed? Some train operator does that when the have to switch modes between auto, coded manual, or restricted manual. Emergency braking can also occur when the train receives the ATP code of STOP. Of course, there are many other situations where such a application is made.

Q3. Sometime when the train stop for too long, or the doors opens for a certain amount of time, i can hear a continuous beep from the driver cabin at times. The beep stops only when the driver closes the door. What is the beep for? I am not certain, but it appears to be something to notify the driver that the timetabled departure time is approaching.

Q4. Who manages the change of signal light from red to white? Automatic? It is automatic and linked to a computer system, which can be over-ridden by a trained personnel.

Q5. Who change the direction of switch on the track at jurong east interchange towards marine bay? Automatic? Should be computerised.

Q5. During emergency brake, we often hear train giving out some ?gases and knocking sounds. What is that for? It is the sound of the air being drained from the equipment, which leads to the application of the physical brakes.

Q6. What training must the driver goes before becoming a train driver? Ask SMRT Trains or SBS Transit. :)

Q7. How does the station knows train will be arriving in X mins? Are there sensors 0n the track? The "Arriving in" is calculated based in the train's position, which is probably gotten from the signalling system.

However, the "Departing in" time given at terminal stations are based on pre-scheduled times, as it is impossible predict when the train operator will decide to depart.

Q8. Noticed that a blue colour box (at night it will shine a blue colour light) beside the track every 400m or so. What is that for? Not sure, never got to see it up-close...

Q9. Why is there stones on a levelled track but not in underground track? The crushed stones, or rather ballast, is present to facilitate the drainage of water from the tracks, distribute the load from the sleepers, and to prevent the growth of vegetation on the tracks from interfering with the track equipment and trains. The first and last reason I have given is not necessary or of less importance underground, therefore there is no need for the presence of the ballast.

Please correct me if I am wrong. :)

TPS Timothy Mok SG

Moderators, please do:

C751A 70049/70050 SG

Moderators, please do:

Why move Trivia thread when this person (TS) does not seemed to testing our skills / knowledge?

Honestly speaking, I was pwned by his qns.

Gus.chong SG

Q1. How does the train behind a train sense the distance and active brake to stop about 1 train length? It's a system called ATP where a continuous stream of information is sent to and from the train. The track is separated into "blocks" of varying length, marked by the following sign.

The train will receive via the ATP appropriate Limit/Target speeds, where Limit is the speed the train can travel up to, while Target is the speed the train must target for as the train approaches the next block. The Limit/Target speed pair will take into account preceding trains, and through varying the target speed, will stop the train before the preceding train.

For more information refer to this article of the LU Central Line's ATP system, which is based on the NS/EWL system.

Q2. When does the train applies emergency brake automatically? Sometime in heavy rain? Approach station at high speed? Some train operator does that when the have to switch modes between auto, coded manual, or restricted manual. Emergency braking can also occur when the train receives the ATP code of STOP. Of course, there are many other situations where such a application is made.

Q3. Sometime when the train stop for too long, or the doors opens for a certain amount of time, i can hear a continuous beep from the driver cabin at times. The beep stops only when the driver closes the door. What is the beep for? I am not certain, but it appears to be something to notify the driver that the timetabled departure time is approaching.

Q4. Who manages the change of signal light from red to white? Automatic? It is automatic and linked to a computer system, which can be over-ridden by a trained personnel.

Q5. Who change the direction of switch on the track at jurong east interchange towards marine bay? Automatic? Should be computerised.

Q5. During emergency brake, we often hear train giving out some ?gases and knocking sounds. What is that for? It is the sound of the air being drained from the equipment, which leads to the application of the physical brakes.

Q6. What training must the driver goes before becoming a train driver? Ask SMRT Trains or SBS Transit. :)

Q7. How does the station knows train will be arriving in X mins? Are there sensors 0n the track? The "Arriving in" is calculated based in the train's position, which is probably gotten from the signalling system.

However, the "Departing in" time given at terminal stations are based on pre-scheduled times, as it is impossible predict when the train operator will decide to depart.

Q8. Noticed that a blue colour box (at night it will shine a blue colour light) beside the track every 400m or so. What is that for? Not sure, never got to see it up-close...

Q9. Why is there stones on a levelled track but not in underground track? The crushed stones, or rather ballast, is present to facilitate the drainage of water from the tracks, distribute the load from the sleepers, and to prevent the growth of vegetation on the tracks from interfering with the track equipment and trains. The first and last reason I have given is not necessary or of less importance underground, therefore there is no need for the presence of the ballast.

Please correct me if I am wrong. :)

For Q7, I thought the SBS Transit trains are driverless?

C751A 70049/70050 SG

For Q7, I thought the SBS Transit trains are driverless?

Yes, NEL (SBST trains) & CCL are driverless and it has nothing to do with Qn 7.

theWEIRDme SG

this dude is like lazy or whut. he can email smrt or check from books and internet.

Interception_7 SG

Q1. How does the train behind a train sense the distance and active brake to stop about 1 train length? It's a system called ATP where a continuous stream of information is sent to and from the train. The track is separated into "blocks" of varying length, marked by the following sign.

The train will receive via the ATP appropriate Limit/Target speeds, where Limit is the speed the train can travel up to, while Target is the speed the train must target for as the train approaches the next block. The Limit/Target speed pair will take into account preceding trains, and through varying the target speed, will stop the train before the preceding train.

For more information refer to this article of the LU Central Line's ATP system, which is based on the NS/EWL system.

Q2. When does the train applies emergency brake automatically? Sometime in heavy rain? Approach station at high speed? Some train operator does that when the have to switch modes between auto, coded manual, or restricted manual. Emergency braking can also occur when the train receives the ATP code of STOP. Of course, there are many other situations where such a application is made.

Q3. Sometime when the train stop for too long, or the doors opens for a certain amount of time, i can hear a continuous beep from the driver cabin at times. The beep stops only when the driver closes the door. What is the beep for? I am not certain, but it appears to be something to notify the driver that the timetabled departure time is approaching.

Q4. Who manages the change of signal light from red to white? Automatic? It is automatic and linked to a computer system, which can be over-ridden by a trained personnel.

Q5. Who change the direction of switch on the track at jurong east interchange towards marine bay? Automatic? Should be computerised.

Q5. During emergency brake, we often hear train giving out some ?gases and knocking sounds. What is that for? It is the sound of the air being drained from the equipment, which leads to the application of the physical brakes.

Q6. What training must the driver goes before becoming a train driver? Ask SMRT Trains or SBS Transit. :)

Q7. How does the station knows train will be arriving in X mins? Are there sensors 0n the track? The "Arriving in" is calculated based in the train's position, which is probably gotten from the signalling system.

However, the "Departing in" time given at terminal stations are based on pre-scheduled times, as it is impossible predict when the train operator will decide to depart.

Q8. Noticed that a blue colour box (at night it will shine a blue colour light) beside the track every 400m or so. What is that for? Not sure, never got to see it up-close...

Q9. Why is there stones on a levelled track but not in underground track? The crushed stones, or rather ballast, is present to facilitate the drainage of water from the tracks, distribute the load from the sleepers, and to prevent the growth of vegetation on the tracks from interfering with the track equipment and trains. The first and last reason I have given is not necessary or of less importance underground, therefore there is no need for the presence of the ballast.

Please correct me if I am wrong. :)

Hi Joey, would like to correct/add more answers to the above :)

Q4. Who manages the change of signal light from red to white? Automatic? All the signallings are controlled from the HQ. Stations can also control the signals, but this will only be made if the HQ is unable to set/reset the signals.

Q5. During emergency brake, we often hear train giving out some ?gases and knocking sounds. What is that for? That should be because the air in the main reservoir is being released to 0. In emergency brake applications, most of the air kept in the reservoir will be used so that the train can stop in the shortest time possible.

Q8. Noticed that a blue colour box (at night it will shine a blue colour light) beside the track every 400m or so. What is that for? Inside the box, contains a phone to contact a nearby station or HQ for assistance needed. It should only be used for emergency purposes. The TO or any staff working on the main line may operate this if needed.

--

If you have any questions or are still in doubt, you may wish to direct your questions to the "Questions on MRT/LRT" thread. Thank you and have a nice day ahead.

joeyfjj SG

this dude is like lazy or whut. he can email smrt or check from books and internet.

This dude is like unproductive or whut. He can just not reply if he does not have the answers.

Chunghong2004 SG

thanks for the answers

Gus.chong SG

Yes, NEL (SBST trains) & CCL are driverless and it has nothing to do with Qn 7.

Oops, I was referring to Q6, my mistake.

C751A 70049/70050 SG

Oops, I was referring to Q6, my mistake.

For Qn 6, in driverless trains (NEL onwards), the drivers are the "Customer Service Officer" who will drive in times of necessary (When train got breakdown, I have seen several incidents in CCL / NEL). Well, ot a bit, that is why developers of BVESG also got do a train cab of C751A (SBST train) and such. (More details please go BVE forums)

AFAIK, if I am not wrong, the training would involve understanding the controls (How to horn, open / close doors -- I have seen the controls before in 085/086 inside TO cabin and NEL / CCL trains, the lighting system [They can switch off the lights if it goes DNB], the use of microphone (Manually announce, you may see / hear it if that train is going to DNB such as LTE OTP bound) etc.), how to stop the train in CM (Braking in train is more CMI than a bus / car), "playing" with a train simulator (Far better than our BVE one, but that is expensive million $$ budget one and not available outside SMRT / SBST while BVE one is free in cost and availbility. I doubt there is a simulator for bus driver) and the ability to react on emergency situations (Like someone pressed ECB a.k.a use the microphone or the ESP pressed on the platform).

This is not comprehensive list anyway, but what I can think of.

I think one may need a Class 3 license (Not 3A) before can start training on this, just like the bus.

Gus.chong SG

For Qn 6, in driverless trains (NEL onwards), the drivers are the "Customer Service Officer" who will drive in times of necessary (When train got breakdown, I have seen several incidents in CCL / NEL). Well, ot a bit, that is why developers of BVESG also got do a train cab of C751A (SBST train) and such. (More details please go BVE forums)

AFAIK, if I am not wrong, the training would involve understanding the controls (How to horn, open / close doors -- I have seen the controls before in 085/086 inside TO cabin and NEL / CCL trains, the lighting system [They can switch off the lights if it goes DNB], the use of microphone (Manually announce, you may see / hear it if that train is going to DNB such as LTE OTP bound) etc.), how to stop the train in CM (Braking in train is more CMI than a bus / car), "playing" with a train simulator (Far better than our BVE one, but that is expensive million $$ budget one and not available outside SMRT / SBST while BVE one is free in cost and availbility. I doubt there is a simulator for bus driver) and the ability to react on emergency situations (Like someone pressed ECB a.k.a use the microphone or the ESP pressed on the platform).

This is not comprehensive list anyway, but what I can think of.

I think one may need a Class 3 license (Not 3A) before can start training on this, just like the bus.

Oh, thank you.

But C751A & C830 are streamlined-front driverless trains, when trains breakdown occurs, which part of the train did they go to drive?

C751A 70049/70050 SG

Oh, thank you.

But C751A & C830 are streamlined-front driverless trains, when trains breakdown occurs, which part of the train did they go to drive?

You can go to the end of the train (1st door on 1st carriage or the last door on last carriage where the 2 emergency exits are), on the right side. where there is a slot for people to go in one. There is a lock there if u see carefully and SBST train used to put a sticker of no sitting / lean, apparently is due to kids who would love to see the "dungeon" (tunnel).

TIB1224Y SG

Hi Joey, would like to correct/add more answers to the above :)

Q4. Who manages the change of signal light from red to white? Automatic? All the signallings are controlled from the HQ. Stations can also control the signals, but this will only be made if the HQ is unable to set/reset the signals.

Q5. During emergency brake, we often hear train giving out some ?gases and knocking sounds. What is that for? That should be because the air in the main reservoir is being released to 0. In emergency brake applications, most of the air kept in the reservoir will be used so that the train can stop in the shortest time possible.

Q8. Noticed that a blue colour box (at night it will shine a blue colour light) beside the track every 400m or so. What is that for? Inside the box, contains a phone to contact a nearby station or HQ for assistance needed. It should only be used for emergency purposes. The TO or any staff working on the main line may operate this if needed.

--

If you have any questions or are still in doubt, you may wish to direct your questions to the "Questions on MRT/LRT" thread. Thank you and have a nice day ahead.

As our trains do not use straight air pipe system, the correct explanation for question 5 is actually the release of air from the immediate brake pipe line valve in a manner like the ABS (Anti-lock Braking System) of a car. The pssh pssh sound is when the air is released from the brake pipe line in a rushed manner. B3 air brake pressure is about 2.8 bar (280 kPa/40.6 PSI), and EMG brake is about 1.0 bar higher than this. Releasing this amount of pressure would generate sounds like that.

There are two main types of air brake systems, straight air and automatic electric command.

Straight air would mean that the brake piping from the reservoir to the brake mechanism is pressurised during normal operations. Normal braking is achieved by adjusting the brake pressure from the brake pipe to the brake mechanism. The reservoir will top up the brake pipe pressure when it drops. It would require mechanical levers to achieve a ABS function, if any. Straight air pipe trains seldom have ABS functions. When the pressure applied is sufficient to overcome the wheel adhesion with the rail, it will cause the wheels to lock-up. In an emergency situation, the pressure in the brake pipe line will be emptied to the brake mechanism to provide the EMG braking effect to the brakes. It does not account for wheel slip (as it does not have ABS) and recharging time simply means recharging the brake pipe pressure to its standby level (usually the equivalent of the EMG brake pressure).

Automatic electric command brake system would use microprocessor control to adjust brake demand together with electric brake (regenerative braking) to achieve the adequate braking demand. It does not need to empty its brake pipe pressure to achieve EMG braking effect, all it does is to adjust the pressure from the reservoir to provide the braking pressure. The pipe line will not have any pressure when no air brake is needed/applied. That is why drivers complain that electric command brake has a slower response than straight air pipe brakes. However, in accidents that involve brake pipings, straight air pipe brakes are much more dangerous than electric command brakes, as they are activated using a main brake pipe line while electric command brake systems have individual pipe lines and are activated individually using automated electric signals, thus failsafe. This would also provide further levels of failsafe like EMG braking on individual carriages when the CPU senses separation from the main train formation (breaking of coupler etc). This function can only be disabled when the train goes into the yard and needs to be separated. This function is also present on all MRTC trains.

All MRTC trains use the electric command brake system, however, when ATP is tripped, the holding of emergency braking is akin to the straight air pipe system, simply because the brake pressure can only be released after the train has come to a complete stop! This scenario may have caused some confusion as to what braking system our trains have, but through MRTC documents this (electric command brake) can be confirmed.

Hope this technical tibit have cleared some confusion.

Interception_7 SG

As our trains do not use straight air pipe system, the correct explanation for question 5 is actually the release of air from the immediate brake pipe line valve in a manner like the ABS (Anti-lock Braking System) of a car. The pssh pssh sound is when the air is released from the brake pipe line in a rushed manner. B3 air brake pressure is about 2.8 bar (280 kPa/40.6 PSI), and EMG brake is about 1.0 bar higher than this. Releasing this amount of pressure would generate sounds like that.

There are two main types of air brake systems, straight air and automatic electric command.

Straight air would mean that the brake piping from the reservoir to the brake mechanism is pressurised during normal operations. Normal braking is achieved by adjusting the brake pressure from the brake pipe to the brake mechanism. The reservoir will top up the brake pipe pressure when it drops. It would require mechanical levers to achieve a ABS function, if any. Straight air pipe trains seldom have ABS functions. When the pressure applied is sufficient to overcome the wheel adhesion with the rail, it will cause the wheels to lock-up. In an emergency situation, the pressure in the brake pipe line will be emptied to the brake mechanism to provide the EMG braking effect to the brakes. It does not account for wheel slip (as it does not have ABS) and recharging time simply means recharging the brake pipe pressure to its standby level (usually the equivalent of the EMG brake pressure).

Automatic electric command brake system would use microprocessor control to adjust brake demand together with electric brake (regenerative braking) to achieve the adequate braking demand. It does not need to empty its brake pipe pressure to achieve EMG braking effect, all it does is to adjust the pressure from the reservoir to provide the braking pressure. The pipe line will not have any pressure when no air brake is needed/applied. That is why drivers complain that electric command brake has a slower response than straight air pipe brakes. However, in accidents that involve brake pipings, straight air pipe brakes are much more dangerous than electric command brakes, as they are activated using a main brake pipe line while electric command brake systems have individual pipe lines and are activated individually using automated electric signals, thus failsafe. This would also provide further levels of failsafe like EMG braking on individual carriages when the CPU senses separation from the main train formation (breaking of coupler etc). This function can only be disabled when the train goes into the yard and needs to be separated. This function is also present on all MRTC trains.

All MRTC trains use the electric command brake system, however, when ATP is tripped, the holding of emergency braking is akin to the straight air pipe system, simply because the brake pressure can only be released after the train has come to a complete stop! This scenario may have caused some confusion as to what braking system our trains have, but through MRTC documents this (electric command brake) can be confirmed.

Hope this technical tibit have cleared some confusion.

Ok. Thanks for the clarification, TIB1224Y. Learnt something new today!

Merry X'mas! :)

Gus.chong SG

You can go to the end of the train (1st door on 1st carriage or the last door on last carriage where the 2 emergency exits are), on the right side. where there is a slot for people to go in one. There is a lock there if u see carefully and SBST train used to put a sticker of no sitting / lean, apparently is due to kids who would love to see the "dungeon" (tunnel).

Thanks for this answer.

As romanista2001 SG

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willis_chong SG

Q7. How does the station knows train will be arriving in X mins? Are there sensors 0n the track? The "Arriving in" is calculated based in the train's position, which is probably gotten from the signalling system.

However, the "Departing in" time given at terminal stations are based on pre-scheduled times, as it is impossible predict when the train operator will decide to depart.

Addon for this, similarly for stations near any terminus, the arrival time above travel time from terminus to current station is predicted by shedule, and thereafter by the sensors.

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