Railway line speeds - how are they determined ?

[whiffey]

Watching railway videos, I see that the line speed can vary by very small amounts, e.g. there may be a long spell of 100mph working which suddenly drops to 95mph for no reason I can see, then back up to 100mph and so on.

Does anyone know how line speeds are worked out, and in particular what would determine a very small reduction - 100 to 95 ?

[CHOPSUEY]

Yawn...

[Mortartube]

From what I can gather, it helps to reduce wear and tear on the track and other hardware. A slight bend might see a small speed reduction whereas a sharper bend would see a larger reduction. I don't know how it is calculated but this seems to be the general gist of it, also I suppose it would add a little to the comfort of the passengers too.

[Gromit]

When a new piece of line is built, they send trains down at speeds increasing 5mph each time. When one flies off the rails, they know they have reached the optimum speed for that section.

[whiffey]

You may well yawn, but it is fascinating sitting in the cab of a Class 86 electric locomotive right next to the driver as it hurtles from Norwich to Liverpool Street through romantic places like Mellis. All in 90 minutes and without leaving the armchair except for cans of Budweiser.

[CHOPSUEY]

If you were sitting in the cab of a real train I would imagine it to be an enjoyable experience - especially with a bud - but in your armchair watching a film of said journey? Oh my god, the excitement!

[whiffey]

chopsuey, may I ask what you do post-tumescence ? Relaxing in an armchair watching the countryside flash by is very relaxing.

[CHOPSUEY]

...post-tumescence? You mean of an evening? Family time, martial arts, drinking, friends, one on one time with the wife...

[mrs_overall]

Just out of curiosity whiffey....apart from railway videos, do you own any of the following?
1. A notebook & pen
2. An anorak
3. A thermos flask & tupperware sarnie box
4. A flat cap
5. Any magazines devoted to trains

[whiffey]

MrsO, I collect pens.

I don't have an anorak, but I have a beautiful quilted Versace jacket. No thermos flask, no tupperware except to freeze phalls in, no flat cap (prefer My Little Pony bobble hats), loads of train books and magazines such as Traction Today.

If you see a cyclist at the very northern end of the Brighton platforms at Clapham Junction, it is probably me.

[mrs_overall]

Traction Today? Do you have a bad back then?

Re: My Little Pony - be careful with their merchandise. When my daughter was young I once googled the subject and came across a site that turned my stomach!

[heathfield]

Speed allowed will depend on the state of the track and the track-bed locally. Also, when approaching any potential hazard, like a level crossing. Non-stopping stations and pointwork may also have speed restrictions. And those curves that Mortartube mentions; some may be banked, others not.

[Panic Button]

Gromit's not taking this seriously.

Full marks to Gromit.

[Buenchico]

A Class 86 running from NRW to LST? I've heard of late-running trains but that's ridiculous - that one must be at 2� years late! ('one' withdrew the last Class 86 locos in 2005).

Anywhat, what's romantic about Mellis? It's close to where I live and I can't find anything at all romantic about it! However, it has got one important attraction:
http://www.mellistavern.co.uk/

And what's this about a Class 86 'hurtling' anywhere on that route? After a late start out of NRW (because of late downroad working), a typical journey would involve being delayed at Trowse Junction because of problems with the swing bridge, coming to a stand at Haughley Junction because of a track circuit failure between there and Stowmarket, a delay at Stowmarket while the driver worked out why he'd lost his 'line light' in the cab, another track circuit failure at Bentley, overhead line problems between Chelmsford and Shenfield, a fatality at one of the commuter stations on the approach to London and a points failure immediately outside of LST.

Chris

[whiffey]

Chris, it's a video

http://www.video125.co.uk/acatalog/Catalogue_I ntercity_Norwich_25.html

Maybe it was just a lucky run on this occasion, but it does keep up to linespeed all the way. I have a particularly nostalgic fondness for this route.

p.s. lucky you, living in Norfolk !