The WHR Tunnels
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During Construction - note the red pads placed to make a comfier ride, and reduce vibration
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There are four tunnels on the Welsh Highland Railway. The first is immediately south of Beddgelert, and the other three start approximately 1.5km further south, within a short space of each other at the south end of the Aberglaslyn Pass. This page is mainly concerned with the Aberglaslyn tunnels.
- Main article: Goat Tunnel
The Goat Tunnel (T1) is located behind the Goat Hotel. At 38 metres long, this tunnel was originally completed around 1905 for the Portmadoc, Beddgelert and South Snowdon Railway (PBSSR) but was modified to ease the gradient for the WHR in 1922/3.
In Aberglaslyn Pass there are -
- A medium sized tunnel (T2) at 29 metres long
- A short tunnel (T3) at 9 metres long
- A long tunnel (T4) at 280 metres long
It was a condition of the rebuilding that remedial work was carried out in this area before any other work was done in the Snowdonia National Park.
These three tunnels go back even further than the old WHR, having been planned for the 1901 PBSSR which would have passed through Beddgelert on its way to Llyn Dinas in the Gwynant valley. Work started on them around 1905/6 but there were not finished until 1923 - T4 had only been bored half way. The 1904/6 alignment is slightly different from that planned in 1901.
There is a story behind the building of the tunnels which goes back to 1901 when the National Trust objected to the railway going through the Pass. They wanted it in a tunnel as far as possible and that could have been done (with no expense spared) with the northern end quite close to the river crossing i.e. opposite Gelert's grave not Bryn-y-felin. That would have been about 1300yds long. In the end the NT settled for one 700yds long which would have finished some way north of the northernmost short tunnel. An agreement was reached and the so-called "bargain" made but this does not appear to have been incorporated into the 1901 PBSSR Act. Anyone knowing the Pass would assume that a tunnel that long would be east of the ones actually bored. Quite what the NT expected is impossible to determine.
However the PBSSR had either been devious, or someone was incompetent, as the 1901 plans show the tunnel 20 to 40 ft on the west, i.e. the river side, of the ones actually bored. Such a tunnel is impossible and a track on that alignment would actually be suspended in mid air. So how was it that such a plan was approved in 1901? One assumes that the National Trust had not made a close comparison of the plans and the location. It is possible that the area around the short tunnels was a scree slope (and this is what Sir Douglas Fox said at the hearing) but if it was that big, it would have blocked the river. Why had the engineers not checked more thoroughly that such a tunnel could be bored? Apparently the PBSSR had agreed to make the tunnel 700yds long without consulting the engineers. That sounds the most likely explanation as one doubts the engineers would have risked their reputation by planning something they knew impossible.
So the PBSSR knew all along what they were doing. The National Trust wanted a tunnel 700yds long so they were told that's what they were getting! The crafty part of the plan was that the tunnel they intended to bore was within the limits of deviation so no additional permission was needed. By the time the National Trust found out it would be too late. At the hearing Sir Douglas Fox actually admitted that it would be too expensive to bore a tunnel to the length agreed, although it would be possible by going into the hill.
This information comes from National Archive file MT6 1721 and the above is an edited version of an article which appeared in Welsh Highland Heritage No.37
T4 is the longest tunnel on the network and its lack of ventilation leads to some special operational considerations. Because it is situated on a steep gradient locomotives heading for Caernarfon are working very hard and matters aren't helped by the 5 mph speed restriction before the Tunnel at Nantmor crossing followed by an often wet cutting. Before entering the tunnel all drivers must be confident of reaching the far end. If they do encounter difficulties in the tunnel there is a special procedure to get the train safely out in order to minimise any possibility of suffocation caused by fumes from the loco.