Class 390 and Tunnel discussion

[508-111]

Hi guys probably a random one but does anyone know how many tunnels are between Crewe and London Euston on AWC and are class 390 doors air CONCEALED like TPE 802? And also does anyone else's ear hurt because of the pressure when a train goes speeding through a tunnel? Cheers

 

[LiftFan]

I certainly used to feel the pressure difference on the HSTs going through Box Tunnel, these days don’t feel it nearly as much although not sure if that’s from the IETs or if it’s from when they lowered the tunnel floor to make room for OHLE.

 

[Bald Rick]

Yes the 390s are pressure sealed. There are 9 tunnels between Crewe and London (via Weedon):

Shugborough
Kilsby
Stowe Hill
Linslade
Northchurch
Watford
Kensal Green
Primrose Hill
Park Street

 

[LNW-GW Joint]

The worst tunnel in the old days for pressure pulses was Kilsby south of Rugby, with its two big intermediate vent shafts.
So you got three pulses on every trip, as wel as from passing trains.
These days with 390s/221s, I'm not sure you feel anything but the momentary change in the light and "feel" as you pass the vent shafts.
The speed limit through Kilsby tunnel is still 110mph rather than 125mph, I think because of the pressure pulses involved.
The shorter tunnels, which is most of them, don't have vent shafts.

 

[Huntergreed]

Certainly on a Avanti 221 you can very much feel the pressure changes, my ears normally go when passing Kilsby tunnel!

This isn’t usually the case on a 390 I’ve found, just gets brighter and quieter momentarily as you pass the ventilation shafts.

 

[TurboMan]

I certainly used to feel the pressure difference on the HSTs going through Box Tunnel, these days don’t feel it nearly as much although not sure if that’s from the IETs or if it’s from when they lowered the tunnel floor to make room for OHLE.

Rumour has it that Alderton tunnel (between Swindon and Bristol Parkway) was restricted to 110mph in each direction (instead of 125mph as on the rest of that stretch) as the pressure resulting from 2 HSTs meeting with a closing speed of 250mph was likely to cause some blow back from the toilet if you flushed it at the wrong moment. It's been raised to 125 now that everything running that way has retention tanks.

 

[spyinthesky]

Hi guys probably a random one but does anyone know how many tunnels are between Crewe and London Euston on AWC and are class 390 doors air CONCEALED like TPE 802? And also does anyone else's ear hurt because of the pressure when a train goes speeding through a tunnel? Cheers

If you ears hurt it might be worth having them checked.
I have one of my ears that has an unbalanced pressure between the inner and outer ear and causes me issues when flying in that it sometimes takes a few hours back on the ground before it pops.

 

[Bald Rick]

The shorter tunnels, which is most of them, don't have vent shafts.

Some of them do, notably Northchurch just north of Berkhamsted, and Stowe Hill near Weedon, both of which are 125mph and had pressure relief shafts built specifically to enable the linespeed to be raised. The only other tunnel at 125mph on the WCML is Linslade (Leighton Buzzard) which is shorter (just!) than an 11 car Pendolino and is configured in a way that two Class 390s can not pass each other at 125mph.

Tunnel aerodynamics for railways are a fascinating (and niche) subject!