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Tunnel length visibility

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Greetlander

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Noticed on another one of the excellent Don Coffey videos earlier that when you enter Summit Tunnel, you can see the pinprick of light 1.6miles away at the other end. What is the longest tunnel length in the UK where you can see one end from the other?
 
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Mintona

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Chipping Sodbury Tunnel is more than two miles long and arrow straight so can see straight through during daylight. That’s probably not the longest though.
 

Taunton

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Just to start us off, Brunel's Box Tunnel, nearly 2 miles, has the sunrise shine right through it, on Brunel's birthday.
 

Scotrail84

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Kilsby tunnel is around 1m,666yds long and is straight I think. Also has huge vent shafts built in and is rumoured to be haunted by navvies who perished during its construction.
 

Spartacus

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Just to start us off, Brunel's Box Tunnel, nearly 2 miles, has the sunrise shine right through it, on Brunel's birthday.

Not quite his birthday’s on the 9th, and it does it on the 6th, or 7th on a leap year, either because he didn’t account for atmospheric refraction, or because he wanted it on his sister’s birthday. Or it’s just a fluke it’s close to either.
 

The Lad

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I noticed recently that one of the tunnels between Halifax and Bradford appears to have strengthening frames in the roof, any idea which one?
 

Grecian 1998

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Kilsby (2224m / 1 mile 666 yards) and Box (2939m / 1 mile 1454 yards) you can definitely see straight through. Those calculations might be slightly out as there are usually slight differences in exactly how long a tunnel is . Polhill Tunnel through the North Downs at 2370m / 1 mile 832 yards between Orpington and Sevenoaks can be seen through, as can Clayton Tunnel just north of Brighton at 2065m / 1 mile 499 yards.

Penge I believe you can stand on the platforms at Crystal Palace and Gipsy Hill and see through the tunnel to the next station.

I think the winner would have been the old Woodhead Tunnels closed in 1954. A book I've borrowed from the library, 'The Woodhead Route' by Anthony Dawson, asserts that when the first tunnel opened in 1845, the Sheffield Iris commented it was possible to see daylight straight through the bore from one end to the other. At 4840m / 3 miles 13 yards that's a fair distance. I think the second tunnel opened in 1852 was also straight but the new tunnel opened in 1954 was curved at the western end.

It seems impossible to find photos to prove this though, as with the narrow bore and huge numbers of heavy steam-hauled freight trains using the route every day, daylight would almost always have been blocked out by the sheer volume of smoke in the tunnel during its working life.

Chipping Sodbury seems to be the working winner named so far at 4065m / 2 miles 926 yards.
 
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Llama

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Noticed on another one of the excellent Don Coffey videos earlier that when you enter Summit Tunnel, you can see the pinprick of light 1.6miles away at the other end. What is the longest tunnel length in the UK where you can see one end from the other?
Summit tunnel is sufficiently curved that you can't see directly through it. 95% of it is straight, but there's a slight curve at the Lancashire end and a significant curve at the Yorkshire end (with an associated permanent speed restriction).
 

Llama

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I noticed recently that one of the tunnels between Halifax and Bradford appears to have strengthening frames in the roof, any idea which one?
I'm not aware of any of those in the six tunnels between Halifax and Bradford, there are some with drain pipes though.
 

SlimJim1694

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Strood and Higham tunnels you can see right through the pair of them. I doubt there are two consecutive tunnels that long you can see through both of anywhere else.
 

Llama

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You can see through six tunnels between Edge Hill and Liverpool Lime St, but that's more a technicality than in the spirit of the previous post.
 

MarkyT

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Strood and Higham tunnels you can see right through the pair of them. I doubt there are two consecutive tunnels that long you can see through both of anywhere else.
And at least from a vertical curvature point of view that's because they originally contained a canal.
 
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