Strange high pitch noise some high speed trains make

[HC1998]

A while ago I was in an Azuma to KGX and I noticed when the train got up to line speed it started making this high pitched “whining” sound a bit like this

What could be the cause?

 

[MerlinRail 804]

Also why does it seem to randomly change pitch? Is it to do with braking/applying power?

 

[Mr. SW]

I've wondered this. Is it the disc brakes? With regularly spaced slots, bolt heads or cooling fins, they could be acting like a crude siren. The random pitch changes could be caused by turbulence? Anyone?

 

[Crithylum]

My feeling is that this has something to do with the wheel rail interface. It sounds very similar on all stock types, so is likely caused by something common between different trains.

 

[Bayum]

Corrugation. Trains travelling over track cause specific wear and tear. When wheels ride over this, particularly at speed, it makes a high pitched sound, similar to how a vinyl works if you imagine the grooves etc.

 

[paulmch]

A few years ago there was a very distinctive bit of track just to the south of Great Chesterford station that played the first few notes of the Star Spangled Banner. Very handy for knowing how far along the journey you were!

 

[172007]

My instinct is the rail grinder / milling machine has been over this track recently.

 

[ac6000cw]

Re. noises in the video in the first post - note it's a Stansted Express train, presumably a 745, and possibly captured by someone sitting close to a motor bogie, so I suspect the video sound may well be traction inverter/motor/gear noise - it's reasonably audible if you're sitting close to a motor bogie on a 745 or 755.

 

[pompeyfan]

I’ve noticed on 444s when braking there’s a high pitched whine on board when sat in one of the motor coaches. It’s noticeable but not unpleasant.

 

[satisnek]

Sounds like freshly ground rail to me. The variation in pitch is presumably due to variation of the grinding machine's speed.

 

[Geeves]

If you stand in the vestibule of any electric or loco hauled passenger carriage you'll definitely hear that noise when it gets up to speed. You can't really hear it too much of a DMU. Reminds me of the old days where you could spend the whole journey with the drop light open on a MK3. Just enjoying the 110mph goodness on the WCML etc

 

[MerlinRail 804]

If you stand in the vestibule of any electric or loco hauled passenger carriage you'll definitely hear that noise when it gets up to speed. You can't really hear it too much of a DMU. Reminds me of the old days where you could spend the whole journey with the drop light open on a MK3. Just enjoying the 110mph goodness on the WCML etc

I hear it a tiny bit on the 168s. Not much though

 

[Bald Rick]

Corrugation. Trains travelling over track cause specific wear and tear. When wheels ride over this, particularly at speed, it makes a high pitched sound, similar to how a vinyl works if you imagine the grooves etc.

It’s not corrugation

My instinct is the rail grinder / milling machine has been over this track recently.

It’s recently ground rail. It’s what good rail is supposed to sound like!

 

[NSEWonderer]

I’ve noticed on 444s when braking there’s a high pitched whine on board when sat in one of the motor coaches. It’s noticeable but not unpleasant.

701s take this a bit more further. Very auidable whine when the regen engages.

 

[Trackman]

I always assumed it was the traction motors or coolers.

 

[nilvaj395]

701s take this a bit more further. Very auidable whine when the regen engages.

I remember seeing somewhere that electromagnetic interference with something like the PA system could cause this, but I am not sure at all. On the 777s you can hear both this sound and the traction motors at the same time or you hear the traction motors first and then this sound or vice-versa. I think it only happens on the higher speed sections.

 

[NSEWonderer]

I remember seeing somewhere that electromagnetic interference with something like the PA system could cause this, but I am not sure at all. On the 777s you can hear both this sound and the traction motors at the same time or you hear the traction motors first and then this sound or vice-versa. I think it only happens on the higher speed sections.

Ah I did wonder if it was interfering with the PA.

 

[sprunt]

Can I piggyback on this thread to ask why 700s/717s make a very distinctive sound when stopping/starting?

 

[Starmill]

Can I piggyback on this thread to ask why 700s/717s make a very distinctive sound when stopping/starting?

Do you mean the "mechanical" noises, like moving parts or the "electronic" noises like motors? I think the noise in discussion here is a mechanical "whine" noise made by the wheels on the track (@Bald Rick will correct me if I'm wrong, I always thought that noise was more to do with air pressure but apparently not, it's the rails?), but perhaps you're used to hearing the traction motor sounds which are quite distinctive on the Desiro City units?

 

[Railguy1]

It just sounds like a normal train to me. It would have been helpful if you posted a time stamp of where the different sound is heard.

 

[NSEWonderer]

So, in short, the sound the original poster mentions is primarily related to the rail-to-wheel interface, which at higher speeds resonates loudly enough to be heard. If the track has been freshly ground (by a rail grinder), as some have mentioned, the sound can be even more pronounced. Pitch changes can occur due to gradient and track wear quality, as the grinder doesn't always grind 100% uniformly, this would explain the sudden changes of pitch in the above video aswell as potentially IGBT inverter drive involvement if load is also beind demanded.

Some trains can also amplify the sound further. EMUs, specifically those with IGBT phase inverters, can resonate at certain frequencies with the aforementioned sound through the train body due to loads, etc.

DMUs don't always produce this sound at higher speeds on the same track that it may be heard more clearly by an EMU. This may be due to those DMUs also having a heavier, thicker body build that deadens the sound. Mark 3 carriages etc and newer trains are of a lighter construction, and the skin isn't often as thick, which can allow the sound to travel through more easily.

 

[Crithylum]

It just sounds like a normal train to me. It would have been helpful if you posted a time stamp of where the different sound is heard.

It is a normal train sound. Nothing wrong with your ears.

 

[M!T]

I never really noticed the whining sound until I travelled on 225s but I have since noticed it on Eurostars, HSTs and Azumas. Seems to be present at speeds over 100mph.

 

[milooo]

701s take this a bit more further. Very auidable whine when the regen engages.

Same on the 700s