Tube Trains on the Overground?

[Starkey7]

Why should it matter what speed they go under a bridge at? They're still going to be the same distance away from the brickwork however fast they go...

I've been told that if you want a more comfy seat then go for the fold down disabled seats as they are more padded than the regular fixed seats

Sam, you're a genius.

Also, I quite like the new Overground trains, but they take forever, having closed the doors, to get a flaming move on! They seem to hang about ages, with little beeping noises and clicks and various other utterances!

[tubeguru]

Why should it matter what speed they go under a bridge at? They're still going to be the same distance away from the brickwork however fast they go...

Funny you should mention that, as I was discussing this with someone at work the other day.

Just after Bathampton Junction on the way towards Trowbridge you come to Dundas Aqueduct. The railway line runs under one of the aqueduct's arches at this point, but each track runs through a separate bored tunnel built into the arch. On the down line, a sprinter-type unit can pass through the tunnels at 70mph. An HST can only go at 30mph. The tunnel is on a curve and the movement of the MkIII coaches at 70mph would cause them to crash into the tunnel walls.

The reason that A and C stock trains cannot go as fast as deep-tube stock is to do with the amount of "wobble" that those trains experience over points and in certain tunnels due to their height and bogie characteristics compared to deep-tube stock.

The other factor in both cases (HSTs and tube stock) is one of weight. HSTs are much heavier than sprinters and would probably cause more wear to the track if they were to go round the curves at 70mph. Similarly, I assume that A and C stock trains would cause more damage to the track than deep-tube stock. Certain pieces of track are only maintained for certain linespeeds. Carriage lines 1 & 2 at Kensal Green are maintained for 15mph running. The relief lines next door are maintained for 85mph.

So that more or less covers why different trains have different linespeeds over structures and in certain tunnels.

[Edgemaster]

You only just discovered Clive's site then?

No?

[tubeguru]

You're asking me?

[Starkey7]

Thanks for the explanation Tubeguru; much appreciated.

[Edgemaster]

I saw one outside Ashford (Kent) station on Saturday.

I was sober.

Aha, found some details of the testing they're doing today, 378137 is running back and forth between Ashford and Redhill most of this afternoon for a commissioning trip.

[jamesthegill]

I saw one outside Ashford (Kent) station on Saturday.

I was sober.

Aha, found some details of the testing they're doing today, 378137 is running back and forth between Ashford and Redhill most of this afternoon for a commissioning trip.

You have no idea how pleased I am to have confirmation that I wasn't seeing things.

Now, anything about the pink dragon placed atop it? Chinese new year?

[Edgemaster]

Since this seems to be the de facto ELL thread, I found this on youtube:
http://www.youtube.com/watch?v=tZXFTEmJMrg