why don't some subway trains accelerate smoothly?

[Marco927]

Sometimes when a train accelerates after stopping at a station, the train lurches forward, then stops accelerating, before it accelerates again. As a passenger, it is very uncomfortable, especially if you can't find a seat and have to stand. Why don't the train operators accelerate from a complete stop smoothly? Do you thing CBTC trains give you smoothier rides?

I ride the LIRR, I don't feel the same "stop and start" accelerations on those trains.

[texassubwayfan555]

If this is on a R142A, then it is not the fault of the operators. The bucking is caused by the uncoordinated release of the brakes and application of power by the electronic control system on these trains. This causes the some of the cars to take power while others are still releasing brakes, causing the cars to push and drag each other when the train first accelerates out of the station.

[trainfan22]

Trains sometimes still buck under ATO in CBTC on the line. Usually always an R143, can't recall the R160s ever bucking. 

 

[Via Garibaldi 8]

I also notice this on old Metro-North trains. The same sort of lurching issues. Quite annoying.

[texassubwayfan555]

Someone said that the bucking was a problem specific to the Bombardier/Adtranz MITRAC propulsion trains (R188, R142A, R143), and that the R142A's should be refurbished and have their propulsion replaced.

[553 Bridgeton]

3rd rail gaps as well. Happens at east 180th northbound as the train takes off.

[Marco927]

18 hours ago, texassubwayfan555 said:

If this is on a R142A, then it is not the fault of the operators. The bucking is caused by the uncoordinated release of the brakes and application of power by the electronic control system on these trains. This causes the some of the cars to take power while others are still releasing brakes, causing the cars to push and drag each other when the train first accelerates out of the station.

The redbird #7 train cars were retired 20 years ago. I remember feeling the lurching of the Redbird trains cars when they accelerated from a station stop.

Electric trains have been around for more than 100 years.  Manufacturers of electric trains can't still solve this lurching problem? What are the train manufacturers and MTA doing to eliminate the lurching?

[texassubwayfan555]

The MTA would have to reprogram the traction/brake controls on the R142A's or go the easy route of telling the operates to wait between releasing the brakes and applying power.

[LexAveExp5]

We’d lose a second at every station (it adds up) and then it might roll back depending on the grade

[RandomRider0101]

On 9/27/2022 at 9:13 PM, trainfan22 said:

Trains sometimes still buck under ATO in CBTC on the line. Usually always an R143, can't recall the R160s ever bucking. 

 

 

On 9/28/2022 at 12:34 PM, 553 Bridgeton said:

3rd rail gaps as well. Happens at east 180th northbound as the train takes off.

Yeah, the R160s usually always stop and accelerate smoothly. The Adtranz pack however (R143, R142A/188) are the worst when it comes to this issue.

When you hit a third rail gap, you will definitely feel it on an Adtranz propulsion-equipped train.

[texassubwayfan555]

Yeah, everyone says the problems stem from the Adtranz propulsion.

[RTOMan]

On 9/27/2022 at 5:50 PM, Marco927 said:

Why don't the train operators accelerate from a complete stop smoothly?

Train Operators have no control on a train bucking when we take power.

Its a car equipment issue when not all of the brake shoes release at the same time when they are supposed to.

On 9/27/2022 at 5:50 PM, Marco927 said:

Do you thing CBTC trains give you smoothier rides?

CBTC has nothing to do with how smooth the ride is, it basically controls the spacing between trains.

Edited October 6, 2022 by RTOMan