How are speed limits calculated?

[louis97]

All trains should have 1 minute engineering allowance approaching Tebay, not just 390s.

Noticed that when I had a look in the planning rules, not that everything does!

 

[Clansman]

The present track layouts at Dundee and Inverness both date from the second half of the 1980s and already contain a good number of crossovers and turnouts fit for 40 mph. Those with lower speeds are likely to be constrained by the physical characteristics of the sites.

Aberdeen's layout dates from the early 1980s and looks as though it might benefit from some higher speed turnouts.

Perth's steam age layout needs ripping up and starting again.

More should be done at Aberdeen I reckon, would save a few bob on upgrading the line speeds - although Usan is inevitable sooner or later.

Perth is frankly an outdated disgrace. The approach and tunnel could easily allow for 50mph running as opposed to the current 30mph.
Perth should be a central hub which would easily constitute a large rail depot/stabling point. It's currently wasting away.

 

[superkev]

I may be wrong but I seem to remember reading permisable speeds on curves are often lower in the uk than elsewhere.
K

 

[D1009]

I may be wrong but I seem to remember reading permisable speeds on curves are often lower in the uk than elsewhere.
K

It actually varies in different parts of the UK. Between Taunton and Exeter where the line speed is 100 I feel more lateral G forces than anywhere else in the country. It's a stretch you don't want to try to walk the length of the train to buy a coffee and take it back to your seat.

 

[Bald Rick]

It actually varies in different parts of the UK. Between Taunton and Exeter where the line speed is 100 I feel more lateral G forces than anywhere else in the country. It's a stretch you don't want to try to walk the length of the train to buy a coffee and take it back to your seat.

In this country, almost every line has a maximum of 4.5deg 'cant deficiency', which means the amount of extra 'banking' (super elevation for us track boys) that would be required for a given curve at a given linespeed for the passenger to feel no lateral force.

In a few places, 6deg cant deficiency has been used, notably in the ECML between Newcaslte and Edinburgh, and very possibly between Taunton and Exeter (it's been 2 decades since I've been down there). In such cases the lateral forces on passengers are higher when cornering

Much of France operates on 6deg cant deficiency, but then they look at us and shrug their shoulders when we talk about 25.5 tonne axle loads.

 

[Clansman]

It actually varies in different parts of the UK. Between Taunton and Exeter where the line speed is 100 I feel more lateral G forces than anywhere else in the country. It's a stretch you don't want to try to walk the length of the train to buy a coffee and take it back to your seat.

Clearly you've never been further north than Arbroath then

 

[QueensCurve]

It actually varies in different parts of the UK. Between Taunton and Exeter where the line speed is 100 I feel more lateral G forces than anywhere else in the country. It's a stretch you don't want to try to walk the length of the train to buy a coffee and take it back to your seat.

I always scalded my hands with the Maxpax BR coffee on the reverse curves just south of Winsford. They have been eased now.

 

[Joseph_Locke]

I always scalded my hands with the Maxpax BR coffee on the reverse curves just south of Winsford. They have been eased now.

(image removed - no applicable COSHH assessment found)

Adding the Down Loop?

 

[QueensCurve]

Adding the Down Loop?

I was thinking about just south of Winsford between the convergeance of the slow lines and the station.

I always assumed that the extra two tracks to crewe must have been added east of the original formation and the main lines slewed to connect to the fasts.

since then the turnout speeds on the slow lines has been upgraded to 75mph and I guess the convergeance has moved a little closer to Crewe.

I have never yet seen a suitable COSHH assement for Maxpax coffee (or even a hazard datasheet).

 

[Joseph_Locke]

I always assumed that the extra two tracks to crewe must have been added east of the original formation and the main lines slewed to connect to the fasts.

The current Down fast is now a straight from Hartford to Winsford, so you're probably right.

I have never yet seen a suitable COSHH assement for Maxpax coffee (or even a hazard datasheet).

It could only conclude that it should be disposed of to a licensed processor; definitely not for internal consumption.

 

[Boysteve]

As has been said signalling plays a big part. When the speed limits were raised on the York-Scarborough route in the 1990's some sections were then permissible for 90mph by the 158s. However when heading towards Scarborough (somewhere between Malton and Seamer) the speed limit dropped to 80mph simply to pass a distant signal, and then the speed limit increased again. Presumably the distance between the distant and home semaphores was not large enough to permit 90mph running with a safety overlap. Obviously this lower speed was only really needed in poor weather/fog/snow etc. In clear weather I often wondered how many drivers slowed down when they could see the distant signal was all clear from half a mile away!!!