Cross Over

[whole diary]

[Western Enterprise]

Hello Everyone.
I thought I would just share with everyone my journey in this morning.
I had caught the 8.35 Maidenhead to Paddington ^Turbo, a journey I regularly take. We switch on to the up main just before Slough and cross back onto the relief just after Ealing Broadway.
Passing through Broadway this time, the train was still whipping along at a good speed. Maximum for the unit is 90 and I would say we were probably not far off it.
Anyway we came up to the cross over and went over it at quite a rate of knots. I was in the front carriage and it shocked me from my seat . 
Almost before we had reached the down relief (from up main), the brakes came on, almost emergency like. It was like the driver had just realised the speed was far too high. We continued braking until on the up relief and by this point the speed was noticeably less.
Usually, having used this crossing before, there is a noticeable braking prior to cross-over; followed by power back on once the cross is complete.
I don^t know what the speed limit is across here, but I would suspect 50/60/70?
Perhaps someone can advise?
I presume that the limit on these is set some way below the critical point at which train leaves track (which is also dependent upon rolling stock). 
What sort of safety margin is there?
I am a little concerned that this was dangerous and not a figment of my imagination, and feel I should report this, just in case this is part of a trend, but to whom? 
Incidentally, the unit was 166220!.

[JayMac]

Question for the technical bods.

Aren't such junctions with a large speed differential approach controlled?

At the crossovers east of Ealing Broadway, according to the Sectional Appendix, the speed from Up Main to Down Relief is 70mph for Multiple Units. Speed from Down Relief to Up Relief is 35mph for Multiple Units.

[SandTEngineer]

I can answer later as I'm not at home at the moment and need to have a look at the relevant signalling notices.  However, if I remember correctly the Up Main junction signal at the end of Ealing Broadway station does not have a delayed clearance control to the Up Relief but has other signalling controls associated with it which are somewhat complex.  All of the crossovers that form the junction are 70mph for MU^▸ (Multiple Unit) (that is Multiple Units; which includes Turbos and HSTs^▸ (High Speed Train (Inter City class 43 125 units))).  The Down Relief to Up Relief crossover is however restricted to 35mph for non-MU trains.

[IndustryInsider]

If I remember correctly there is a splitting distant (http://i.imgur.com/BGbIPul.jpg) signal just after West Ealing, which indicates the train will be crossing over the the Up Relief.  You then get a Junction Indicator 1 (http://upload.wikimedia.org/wikipedia/commons/thumb/4/43/Signal-routediverge1.jpg/105px-Signal-routediverge1.jpg) at the signal just off the end of Ealing Broadway station.  I believe the speed is also controlled by a TPWS^▸ (Train Protection and Warning System) overspeed sensor, but I would imagine that would trip at more than the 90mph that a Turbo would be doing as it's designed to ensure trains are braking from 125mph which would result in a derailment!  I believe most points are designed to be safely taken at around 25% over the permitted speed, which would be the equivalent of about 90mph in this case - though it would involve quite a lurch and is not recommended!

SandTEngineer should be able to confirm and elaborate on those details. 

If you wish to report it, then I'd just go through the normal customer service channels - If they consider it necessary they'd be able to pass it on to the driver managers who could arrange for the data recorder to be downloaded - details are held on them for a couple of days at least.

[IndustryInsider]

Almost before we had reached the down relief (from up main), the brakes came on, almost emergency like.

Just to add a couple of points from my post yesterday.  The braking system on a Turbo means that if the emergency brake is selected then you can't deselect it until the train is going less than 6 mph - so in other words it brings you to a grinding halt, so the most the driver could have selected was a 'full service' application.

Also, to add to my comments about a TPWS^▸ (Train Protection and Warning System) overspeed sensor, I had omitted to say that ATP^▸ (Automatic Train Protection) would also control the speed of the train on the 125mph capable stock that is used in the area, so there's no chance of the driver hitting the crossover at 125mph.

[SandTEngineer]

OK, you can find the explanation of how the junction signalling operates at Acton West Junction in Figure 9 to be found here:
http://www.railsigns.uk/info/jcnsig1/jcnsig1.html.

The difference from this drawing and the installation at Acton West Junction is that the 'Preliminary Route Indicator' is not required as the junction turnout (crossover) is designed for a linespeed of 70mph and the approaching linespeed is 125mph. There is sufficient braking distance between the splitting distant signal (SN212) and the Junction Signal (SN204) to allow the necessary braking from the 125mph maximum speed of a HST^▸ (High Speed Train (Inter City class 43 125 units)) or 90mph maximum speed of a turbo to the 70mph of the turnout.

For those that are interested in a more detailed description of this method of junction signalling this can be found in Section 5.2.6 in Railway Group Standard GK/GN0645, Issue 4 to be found here (you need to enter 0645 in the search box as you cannot link to the actual document):
http://www.rssb.co.uk/railway-group-standards

I would not wish to speculate on the speed at which your train took the crossover but if you feel that you are still concerned then I suggest, as Industry Insider has stated in his post above, that you contact GWR^▸ (Great Western Railway) with details of your concern.  It would be interesting to see their response if you are happy to share it.