Template:Moelwyn Tunnels Old & New
Tunnels and Loading Gauge, etc.[edit]
Comparison of Tunnels, etc.
| N | Year | Link | Gradient | Length | Curvature | Tracks | Ventilation | Width $ |
Height $ |
Sides | Roof | Lining | Engineer | Remarks | Notes |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 101 | 1842* 1863+ |
Old Moelwyn Tunnel * Horse Power + Steam power |
1 in 80? x | 730yd | Straight | 1 | 3 | 8' 0" | 9' 6" | Straight | roughly Semi-circle | Stone portals; unlined within | J. Spooner | Replaced 1836 inclines | * No Problems + Nasty, confined, wet |
| 106 | 1977 | New Moelwyn Tunnel | 1 in 80? x | 275yd | Straight | 1 | None | 11' (+/- 3") |
12' (+/- 6") |
Straight | Low arc | Shot Concrete (Shotcrete) |
M.A. Schumann; the Three Miners |
Deviation avoids flooding | Comfortable |
| 201 | 1851 | Garnedd Tunnel | 1 in 80; dips under portals | 60yd | Slightly curved | 1 | No | 8' 0" | ca.10' | roughly straight | Semi-circle, stone portals | Mostly unlined; brick piers in places | J. Spooner | Deviation of 1836 route | |
| 701 | 1836 | FR Structure gauge | 8' 0" various cuttings, now less; was ca.7' at Cemetery 1963 | 8' 6" (to 1956) but 9' 8"(since 1963) Rhiw Plas | Smallest bridge or tunnel | GS | |||||||||
| 705 | 1836 | FR Loading gauge | 6' 2" plus in-swing at carriage centres | 9ft +/- 3ins | Largest rolling stock | GL |
- Notes: N/A = Not Available.
- x Notes: Ruling Grade about 1 in 80.
- + Notes: At ruling gradient.
- $ Notes: Structure gauge and loading gauge are not simple rectangles.
Gallery[edit]
-
Tunnel profile Old Moelwyn Tunnel
An unpleasant tunnel in steam days. -
New tunnel (right) looks much wider
than the old tunnel (left). -
Tunnel profile New Moelwyn Tunnel -
Garnedd Tunnel west portal
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Rathole[edit]
A rathole tunnel is so-called when a combination of factors make it difficult, unpleasant, and even dangerous to operate, including
- gradient too close to the ruling gradient.
- length longer than the "momentum distance".
- wet rails from steam and/or water seepage.
- unhelpful wind direction.
- train load too close to full load.
- loading gauge too close to the structure gauge.
- awkward stop at bottom of tunnel.
- insufficient time between trains for smoke to clear.
- single line rather than double line.
- lack of escape route for crew in case of stall.
- even great engineers made mistakes and rathole tunnels.
There is a standing instruction to enginemen on the FR that in the event of the engine coming to a stand in a tunnel, the train must run back by gravity outside the tunnel before any effort is made to blow up steam.