The Anonymous Widower

Noise From Trains Revisited

Nearly, two years ago, I wrote a post entitled Are You Annoyed By Noisy Trains At The Bottom Of Your Garden?.

A few days ago, the post had a comment from a lady saying this.

we live on top of thames link between st pancras and farringdon stations. We are used to the trains having lived here for nearly 30 years. But recently in the last 6 months 2017/2018 the noise and vibration from the trains has increased also the frequency. From before 6am until after 1am in the morning. These new trains make the house rattle and you can feel the vibration through the floor. You have to turn up the radio or TV and visitors always comment on how do you manage to live with it.

No one seems to know anything when I made enquiries to thameslink. Spoke to me as if i was completely mad.

I contacted the lady and the problem seems to be that the eight-car Class 700 trains are the problem.

Now if the twelve-car trains are quieter, it sounds to me, that there must be a peculiar resonance between eight-car trains and the track.

According to Wikipedia, the train formations are.

  • Eight-car – Bo’Bo’+2’2’+Bo’Bo’+2’2’+2’2’+Bo’Bo’+2’2’+Bo’Bo’
  • Twelve-car – Bo’Bo’+2’2’+Bo’Bo’+Bo’Bo’+2’2’+2’2’+ 2’2’+2’2’+Bo’Bo’+Bo’Bo’+2’2’+Bo’Bo’

Note.

  1. Bo’Bo’ is a powered-car.
  2. 2’2′ is a trailer car.
  3. The plus sign separates each car.

From my engineering knowledge, could it be something to do with the fact that the twelve-car train has four trailer cars in the middle of the train, whereas the eight-car train has only two.

I suspect that these trains were designed as twelve-car units and because of the problems of lengthening some platforms, Siemens were asked if they could build an eight-car version as well.

With the dynamics tuned to the twelve-car train, I’m not surprised that the eight-car trains create an annoying resonance.

I shall be using my Freedom Pass to investigate this phenomenon, by riding in the middle sections of these trains.

April 6, 2018 - Posted by | Travel | ,

3 Comments »

  1. How interesting!

    Comment by Little Miss Traveller | April 6, 2018 | Reply

  2. An excellent piece of detective work…and yet another example of the law of unintended consequences.

    Comment by Alan Boyce | April 6, 2018 | Reply

    • In the 1960s, I used to work on a PACE 231R analog computer, to solve various dynamic problems in chemical plants.;

      One of the problems the section was dealing with was the mathematics of whirling shafts in the reactors for making polythene. I believe the guy doing it had correspondence with British Rail research who were looking at the dynamics of railway wagons, which kept derailing. BR solved the problem and could that resarch have led tosome of the wonderful bogies designed by Bombardier?

      I will get to the bottom of this.

      Comment by AnonW | April 6, 2018 | Reply


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