730 Abrupt Slowing

[Class 323221]

Hello Everyone,

Quite often, when I am on the 730s, they begin departing out of a station or through what was a signal at danger. You can hear the traction motors as the train accelerates for a couple of seconds. Then the train slows down, the traction motors cut out after the train starts slowing, the brakes hiss and then the train continues on its way. It doesn't always become stationary, just very close to being stationary. I think it's a bit odd seeing as you can stil hear the motors. Does anyone know why this happens? I have a theory that it could be something like hill start but I'm not too sure.

Thank you

 

[John Webb]

Are these trains leaving a terminus station or one where they've been turned round? What you describe sounds like a 'Running Brake Test' which drivers must do soon after moving off from a terminus or other turn-round point to check all is working as it should.

 

[800001]

Hello Everyone,

Quite often, when I am on the 730s, they begin departing out of a station or through what was a signal at danger. You can hear the traction motors as the train accelerates for a couple of seconds. Then the train slows down, the traction motors cut out after the train starts slowing, the brakes hiss and then the train continues on its way. It doesn't always become stationary, just very close to being stationary. I think it's a bit odd seeing as you can stil hear the motors. Does anyone know why this happens? I have a theory that it could be something like hill start but I'm not too sure.

Thank you

Are you sure you are passing signals at danger?

Most likely a proceed aspect signal which changes to red once train passes it, you are then seeing the red signal.

 

[AJDesiro]

I believe there is (or was) an issue with the hill hold system where the system engages after the train has just started moving. At least that's what I overheard from a guard instructor training up some guards on the units a while back.

 

[JLX5]

I believe there is (or was) an issue with the hill hold system where the system engages after the train has just started moving. At least that's what I overheard from a guard instructor training up some guards on the units a while back.

Still is the case. The brakes don’t fully release for some reason and the only way to get them to release is to go into coast and back into power, sometimes you don’t have enough speed to do this quick enough so you come to a stand and have to start all over again.

The extra hiss from the brakes that the OP is referring to is this process of going into coast and then back into power which makes the brakes fully release.

Alstom spent a good few months at the start blaming drivers but have since acknowledged it is a software issue with an update to address the problem supposedly being released by the end of 2024. Here we are over half way through 2025 still with nothing.

 

[800301]

Still is the case. The brakes don’t fully release for some reason and the only way to get them to release is to go into coast and back into power, sometimes you don’t have enough speed to do this quick enough so you come to a stand and have to start all over again.

The extra hiss from the brakes that the OP is referring to is this process of going into coast and then back into power which makes the brakes fully release.

Alstom spent a good few months at the start blaming drivers but have since acknowledged it is a software issue with an update to address the problem supposedly being released by the end of 2024. Here we are over half way through 2025 still with nothing.

So this must be a common 720/730 problem as the Greater Anglia units do it but I’ve never noticed it on a 345

 

[NSEWonderer]

I do hear that the 720s had an issue where if you didnt take full power from a standing start it wouldn't release the holding brakes properly and bring it all to a stop. I assume thats the issue 730s face? With 701s we first move the Traction brake controller into Coast and then into the appropriate power % after.

They've however been "fine so far with going straight into power" but its much more appropriate to bring it into Coast first before moving and then into power with the 701s. No clue how that will work on 730s or of they have a software specfic issue.

Does seem to be Alstom having a few brake related software stuff to fix on most of Aventras.

 

[Class 323221]

Are you sure you are passing signals at danger?

Most likely a proceed aspect signal which changes to red once train passes it, you are then seeing the red signal.

I am definitely sure. The train comes to a halt and traksy confirms it's a signal at danger.

== Doublepost prevention - post automatically merged: 10 Sep 2025 ==

Are these trains leaving a terminus station or one where they've been turned round? What you describe sounds like a 'Running Brake Test' which drivers must do soon after moving off from a terminus or other turn-round point to check all is working as it should.

The times I have noticed it is at a station within the route, not a terminus.

== Doublepost prevention - post automatically merged: 10 Sep 2025 ==

I believe there is (or was) an issue with the hill hold system where the system engages after the train has just started moving. At least that's what I overheard from a guard instructor training up some guards on the units a while back.

I thought it could be this as you could still hear the traction motors. There is another post that also makes sense as well. Thank you for your help.

== Doublepost prevention - post automatically merged: 10 Sep 2025 ==

I do hear that the 720s had an issue where if you didnt take full power from a standing start it wouldn't release the holding brakes properly and bring it all to a stop. I assume thats the issue 730s face? With 701s we first move the Traction brake controller into Coast and then into the appropriate power % after.

They've however been "fine so far with going straight into power" but its much more appropriate to bring it into Coast first before moving and then into power with the 701s. No clue how that will work on 730s or of they have a software specfic issue.

Does seem to be Alstom having a few brake related software stuff to fix on most of Aventras.

This makes a lot of sense. It does sound similar. Maybe the brakes aren't releasing in time but the power is enough to move the train as they release, before it stops itself perhaps? Thanks for your help.

 

[pdeaves]

I am definitely sure. The train comes to a halt and traksy confirms it's a signal at danger.

Are you describing a) a train stopping at a red signal, then proceeding once the signal clears (normal operation), or b) a train routinely passing a red signal (big problems)?

 

[NSEWonderer]

Are you describing a) a train stopping at a red signal, then proceeding once the signal clears (normal operation), or b) a train routinely passing a red signal (big problems)?

Or has the train actually been the one to activate the red by way of normal passage by it.

 

[Class15]

Are you sure you are passing signals at danger?

Most likely a proceed aspect signal which changes to red once train passes it, you are then seeing the red signal.

I think @Class 323221 actually meant heading away from a signal that was previously red and the train moves when it turns to proceed?

 

[Liam L]

I am definitely sure. The train comes to a halt and traksy confirms it's a signal at danger.

Sounds like to me that the train has proceeded through the signal and trasky has updated the train has moved into the next block section then the 730s 'throw a hissy' as I like to describe it and the brakes bring the train to a stop

However trasky isn't the greatest when it comes to relibity when it comes to showing signal aspects. Opentimetrains is often far superior.

 

[Class 323221]

Are you describing a) a train stopping at a red signal, then proceeding once the signal clears (normal operation), or b) a train routinely passing a red signal (big problems)?

Sorry, I wasn't clear. A - Normal Operation

I think @Class 323221 actually meant heading away from a signal that was previously red and the train moves when it turns to proceed?

Yep, this is what I meant.

Sounds like to me that the train has proceeded through the signal and trasky has updated the train has moved into the next block section then the 730s 'throw a hissy' as I like to describe it and the brakes bring the train to a stop

However trasky isn't the greatest when it comes to relibity when it comes to showing signal aspects. Opentimetrains is often far superior.

It was definitely a red signal. Crew also announce this. I don't recall it happening as frequently as at stations, but I haven't been stopped at danger as much as at stations.



To clarify - The signal was definitely at danger. The train proceeds through it once the signal goes to clear. I am definitely sure.

 

[800001]

I think @Class 323221 actually meant heading away from a signal that was previously red and the train moves when it turns to proceed?

They state signal passed at danger in the opening post. Which is why I asked what o did.

 

[Class15]

They state signal passed at danger in the opening post. Which is why I asked what o did.

No they didn’t. They stated “what was a signal at danger”.

 

[800001]

No they didn’t. They stated “what was a signal at danger”.

Ok. Read it how you want, I will
Read it how I do.

Read #8 to what they also wrote.

 

[pompeyfan]

Could it be that because the signal is restrictive after stepping up from red, drivers are only taking a low power setting and that’s why the holding brake is sticking? Same would apply for platforms with low speed departures like Birmingham New Street etc etc.

 

[JLX5]

Could it be that because the signal is restrictive after stepping up from red, drivers are only taking a low power setting and that’s why the holding brake is sticking? Same would apply for platforms with low speed departures like Birmingham New Street etc etc.

It happens even when taking full power straight away.

 

[66701GBRF]

Ok. Read it how you want, I will
Read it how I do.

Read #8 to what they also wrote.

I agree, I read it as passing a signal at danger on both those posts.