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The London underground doesn't use a yellow (intermediate) aspect for a few reasons 1- Very short times between trains 2- All trains stop at every system 3- Stopping distances are so short All these mean that the underground doesn't benefit from a three aspect signal

@@reliantrailways Thank you for your response there. I'm sure that's valid on the vast majority of London underground tracks. However there are some sections of track on the London underground that are indeed quite lengthy. Examples of which can be found on the Metropolitan Line, for example, between Finchley Road and Wembley Park. I recollect that trains on this section can run pretty fast (70 mph). There are some sections of the London underground that use same tracks as mainline railways. How does this marry together?

A great insight there!

If the driver can’t see any signal because of snow he must stop and report it .

And the red is at the bottom because it’s closest to the drivers line of sight.

@@bigal5791 yea

Thanks for the extra info!

Maybe, although I don't own a K2 at the moment, I may purchase one as I am after more engines

The class 60s are very powerful yes

Thank you!

Thanks very much James

Thank you!

I got it a while back at my local model railway exhibition (Rainhill) it cost me £35! It has lights and runs well with a driver figure installed, my best purchase ever

I have been playing with variations of my layout, it's the same usual 3 tables

Thank you very much!

Thank you very much!

@@reliantrailways anytime

except the western region. nuff said

Quite simple Western region chose lower Quadrant every other region chose upper. nothing to do with being less safe. And your quoting Thomas the Tank as a signalling guide.

when semaphore signals were first introduced, lower quadrant signals were used. However, it was evident that there was a problem: when the wire snaps, gravity pulls the signal arm down around the pivot (since the wire is no longer providing a counter force), and the signal shows a proceed aspect, when in fact it should be a danger aspect. I haven't seen the thomas the tank engine episode you are referring to, but i would assume thats what happened in the episode. This type of failure is very bad. It is referred to as a wrong side failure: where a piece of equipment shows a "false positive" (a signal showing proceed when it should show stop) In signalling (and other safety critical systems), you need to ensure that should a failure occur, the most restrictive information should be shown. This would mean that should the semaphore signal fail (due to a wire snapping), then the signal should default to a danger aspect. This is called a right side failure: where a signal should show proceed, but instead a danger aspect is shown. Early railway companies had to solve this issue, as currently with the lower quadrant semaphore, the very bad wrongside failure could occur. Most railway companies fixed this by introducing the upper quadrant signal. Using the very thing that made the wrong side failure occur, the upper quadrant signals were "failsafe". should the wire snap, gravity (the thing that caused the wrongside failure in the lower quadrant signals) will pull the signal down into the danger aspect. This solution did have a drawback: drivers now needed to be retrained (or at least told) that the new proceed aspect is a raised arm, rather than a low arm. But this was a minor drawback, so most railway companies used this solution, including the vast majority of signals in the uk right now (in fact i dont think there are any lower quadrant semaphores left on the national rail netwrok, but i might be wrong) Great Western Railway (GWR), however, were stubborn. They did not want to adopt this upper quadrant system to make their signal failsafe, so they came up with a different method. GWR installed counterweights on the signal, weights that were heavy enough to pull the signal to danger should a wire snap. When the signalman pulls the lever, they are pulling the counterweight UP, thus allowing the signal to be lowered. Whilst GWR came up with a rather strange and convoluted solution, it worked. should the wire snap, as explained before, the counterweight falls, pulling the signal into the horizontal danger position. GWR made them FAILSAFE, as long as they were installed with counterweights. I can assure you that since GWR installed their method, the lower quadrant signals are no less (or more) safe than upper quadrant signals.

@@j.a.g1291 A lower quadrant signal will return to danger in the same way as an upper quadrant. Firstly, the lens adds a fairly significant amount of weight, which is usually enough to counterbalance the arm, and, even if the lens isn't heavy enough, lower quadrants are all counterbalanced anyway, with a rigid steel rod acting from the counterweight to the arm, so if the cable snaps it will help push the arm back to danger (if you build a ratio signal kit it may help you understand). Lower quadrants are just as safe as upper quadrants (and, in my opinion, easier to see).

Your incorrect.

@@railwaymechanicalengineer4587 Try this one then, from MP12 driver training 1985.This signal can be passed in a direction that when it is cleared does not apply too.

I'm not local to Nottingham so I'm not sure, but those 2 car units both terminated there, split, one went one way and one went the other way

That's a very interesting story, typical chairman.

Try your best and look at some railway series images

Thanks!

Some signals do go down, but the main reason to go up is to avoid snow / debris forcing the signal down and showing all clear all the time

@@reliantrailways Oh? Makes sense! ;) Thanks! ;) If only it were designed that way then Henry wouldn’t of had his crash pulling the flying kipper

Different rail networks also

safer. if you snap the wire, it goes to danger.

​@@bussesandtrains1218incorrect. Both upper and lower quadrant signals will return to their most restrictive aspect if the control cable snaps. This is basic fail-safe design. This is accomplished by the different placement of the lenses with respect to the pivot. With lower quadrant signals, the lenses and their mounting (quite heavy to ensure counter balance even with snow on the arm) are fully to the right of the pivot. Upper quadrant signals have their lenses mostly underneath the pivot, which reduces their effect on the balance of the signal arm to a minimum.

Thanks for the correction, this video is mine, all my content is original and filmed by me

Thank you!

Thanks very much! Glad you enjoyed it

Thanks digger!

Thanks

Thanks very much, glad you like it

Yes, a brilliant man (Ratio)

@@reliantrailways counter ratio

Thank you! Glad you liked it

Thanks! Good rake of coaches those are

Thanks very much!

Thanks very much!