What causes these rail noises?

[trainmania100]

This morning I was at Newhaven harbour for the RHTT and as the 69s approach the station the rails made a shrill noise, not flange squeel but the sound of the rails being incredibly stressed, listen as the train approaches ;

This has happened for as long as I can remember, obviously something to do with maybe the train leaning into the inside rail but this was louder than I can ever remember. Sounds like the rail could crack any minute and the train fall into the platform

 

[RGM654]

Do you mean the knocking/rattling between about 0:30 and 0:50?

 

[furnessvale]

Simply the wheel flanges touching the rails on a curve. Much amplified by the rails being continuous welded, transmitting the noise.

As an aside, this was a godsend in my youth when the noise transmitted by CWR warned of a train before you could see it. This was in the days before regular use of a lookoutman when solo trackwalking, let alone such innovations as red zones.

 

[trainmania100]

Simply the wheel flanges touching the rails on a curve. Much amplified by the rails being continuous welded, transmitting the noise.

As an aside, this was a godsend in my youth when the noise transmitted by CWR warned of a train before you could see it. This was in the days before regular use of a lookoutman when solo trackwalking, let alone such innovations as red zones.

I knew you get a "flashing" kind of noise I remember hearing it on long sections before the train comes but this was definitely on another level

 

[furnessvale]

I knew you get a "flashing" kind of noise I remember hearing it on long sections before the train comes but this was definitely on another level

Yes, on straighter track you get a "twanging" sort of noise, but as the curve gets tighter the loco especially starts to dig in a bit with its flanges. Hence rail sidecut on curved track.

It can sound like it is about to burst the 4ft open but the noise is quite common and I don't believe spreading the 4ft happens too often.

 

[Ploughman]

How frequent is any heavy fright traffic at that location?
If all the traffic is Lighter EMU the the heavy Loco may be forcing the rail downwards causing the creaking.
That is total guess on my part though.

 

[Annetts key]

As well as the causes already discussed, the rails moving in the fixings may make a noise.

Heavy trains may cause the rails to move very slightly outwards in the fixings on concrete sleepers. Caused by the weight of the train putting sideways pressure on the rails. That can make a sound. The reason this happens is that the plastic insulators ("biscuits") and rubber pads suffer from wear over time where they are pressed against / between the housing, fixings and rail. So over time, a very small amount of movement becomes possible. Fiction means that this movement is sudden and hence it makes a noise.

The above is far more noticeable on curves.

Note that in my experience, rails rarely break under a train. In CWR / LWR (continuously welded rail / long welded rail), broken rails most commonly break due to stress during the early hours on very cold nights during the winter. And even then, most times the sleepers and fixings keep the rails in line, so even if a train passes over the break, the train is not likely to derail. So, no, the rails are extremely unlikely to "crack" and cause a derailment.

These sounds are quite common. It is quite surprising how far sound can travel in CWR / LWR. Maybe it appeared to be louder than normal if there was no, little or less than normal background noise, which can happen at night.