Great Western Coffee Shop

I was at Slough at lunchtime and a freight train came through.. As I was bored I counted the carriages and it was an (in my opinion) impressive 38 carriages.. It just made me wonder if there is some sort of limit or if anyone can better that?

The limit in the UK is usually constrained by the length of passing loops, which I believe is around 775m.  No point running a train if you can't loop it to let passenger trains past.

I recall several years ago seeing a train in Winnipeg, Canada, that was 100+ vehicles long. And a quick google indicates that trains of up to 4,000m are common in North America. I just hope the driver doesn't have to pop to the back to check that the tail light is lit very often.  ;D

Hmmm, no comment.

I can remember in the early 1980s being invited to Western Tower opposite Reading Station which was then used as offices by BR and seeing a Foster Yeoman train coming off the Berks & Hants line.  I believe it was 46 wagons plus the loco and was described at the time as either the longest train or the most number of wagons, I forget which.

I do remember it brought the whole station to a standstill as it snaked its way across to the relief lines to head towards Acton.  It has only taken 30 years to get the flyover!

Oh gosh, Jo ... the pedant in me took over and got me wondering how many horseless carriages could be gotten onto a train and I came up with a figure of 132 ...

http://www.eurotunnelgroup.com/uk/eurotunnel-group/operations/le-shuttle/

Eurotunnel offers the fastest, most reliable and easiest cross-Channel service. With the passenger Shuttles, it takes barely 35 minutes to cross the Straits, without having to get out of your car. The Shuttles travel through the Tunnel at a speed of 140 km/h (nearly 90mph) and are capable of transporting 120 cars and 12 coaches each.

I then wondered about the horses ... and it seems they can go too

http://www.eurotunnel.com/uk/traveller-info/pets/Horse-travel/

Although stone trains for Acton will take the new line from Reading West to the Reliefs under the flyover it seems trains will not be able to wait on this line due to possible problems restating such heavy trains on the gradient.

Therefore they will have to be given a clear run from Theale.

Is the gradient a problem? This has been discussed here before and I seem to remember that other posters didn't consider the gradient to be such an issue. Essentially the Up Feeder line from Oxford Road junction goes under the flyover at approximately the same level as the previous lower yard. The embankment carrying the Main Line is about 3 metres high hereabouts so the line has to rise this amount to join the Reliefs over a distance of about 500 metres before the Caversham Road bridge, This gives a gradient of 1 in 166 or thereabouts, within the capability of a Class 59 on a 4,000 tonne train. The acceleration might be a bit slow though! On the other hand the rear of the train will be on the flat or on the falling gradient from Oxford Road to the flyover.

The length of the train might be a bit critical if the positioning of the points and signals means that halting a full length train might block a junction. However NR is working to a standard freight train length of 775 metres so I would hope that a train of this length could be held on the feeder line clear of the junctions at each end. If this is not possible then, as  you say, they will need a clear run.

We'll see!