Snowdon Mountain Railway bridges

There are main seven bridges on the SMR. Three of these are sizeable structures whilst four are the minor crossings over the Llanberis path and two others over the Afon Hwch or its tribituaries. There are two other minor bridges, not described. These are located on the long 1 in 6 incline towards Hebron and another just above Hebron.

The first crossing can be found at the end of the 1 in 50 gradient just 350 yards from Llanberis station. The crossing over the Afon Hwch marks a short section of 1 in 6 that leads to the largest structure on the SMR. This is Lower Viaduct, with a length of 166 yards (500ft.) Fourteen arches rise on a 1 in 8½ gradient, making the next up arch four feet higher than the previous one. One of the arches is larger than the rest and skewed across a minor road in Llanberis.


The large skewed arch near Victoria Terrace, Llanberis © Copyright Gwychder y Wyddfa

Just round the corner is the Upper Viaduct, whose length of 63½ yards and four arches heralds a spectacular view of the Ceunant (or Afon Hwch/Llanberis) falls. The start of this also gives rail passengers and viewers to the waterfall look out point a gllimpse of Snowdon summit 4 miles distant.

Both structures are often known as the Afon Hwch viaducts, but neither actually cross over the Afon Hwch.


Just a very small part of the Lower Viaduct is visible in this picture © Copyright Gwychder y Wyddfa

The Upper Viaduct is smaller than its precessdor. Its perched on the edge of a rocky outcrop that straddles the gorge in which the Ceunant Mawr falls are sited, and it must have poised some difficult construction tasks for the builders of the railway in the 1890’s. Its position commands excellent views of the waterfalls.

Before any tracks could be laid to the summit of Snowdon, these viaducts had to be completed as the railway was to be used to transport materials up the mountain. The viaducts were completed in early November 1895, having taken roughly 10 months to build.


The Upper Viaduct at 600ft (182m) above sea level. The waterfall can just be seen lower right © Copyright Gwychder y Wyddfa

Just below the closed Waterfall station the railway crosses its one and only minor stone arched bridge at Cae Esgob. The railway’s history mentions Cae Esgob bridge but does not tell us which of the two bridges immediately either side of Waterfall halt it refers to. The only clue to this location is the adjacent Cae Esgob farm.


Cae Esgob bridge is just below Waterfall Halt © Copyright Gwychder y Wyddfa


At the end of the gentle 1 in 20 incline above the closed Waterfall station the railway crosses Ceunant Bach bridge, sited 656ft (200m) above sea level. This has a single arch and is the only stone structure to actually cross the Afon Hwch. The lengthy stretch of gently rising 1 in 20 gradient from Waterfall to Ceunant Bach bridge does not require a gripper rail and this explains why Ceunant Bach bridge has the unusual position on the SMR in not having the safety rails.


Ceunant Bach bridge is on a short section of 1 in 10, following the long 1 in 20 from Waterfall station. The lack of gripper rail is obvious.

There’s a picture of Ceunant Bach bridge under construction in one of the railway’s publications, The Snowdon Mountain Railway Souvenir brochure. The accomodation crossing below the bridge must be the easiest to use as one does not have to contend with the gripper rails!

Below – another view of Ceunant Bach bridge. Its so called because it crosses the top end of the Ceunant Bach falls.


There is a minor structure over a tribituary of the Afon Arddu near the accomodation crossing upwards of Ceunant Bach bridge.


The structure at 887ft (252m) over the road to Hadodty Newydd farm. Its known as Cader Ellyll bridge. Gradients of 1 in 12 and 1 in 6 can be seen here as the line climbs to Hebron station © Copyright Gwychder y Wyddfa

Above Hebron there is a small crossing over a tribituary of the Afon Arddu which consists of a cattle grid and lacks gripper rails. The reason for this dual purpose structure is to prevent stray sheep from entering Hebron station’s operational area and the fenced off trackbed downwards to Llanberis © Copyright Gwychder y Wyddfa

The next crossing is that over the Llanberis path, the ‘halfway’ bridge at around 1443ft above sea level. It leads almost immediately into Halfway cutting.

Halfway is a misnomer in terms of ascending Snowdon by train. The station is just over 2¼ miles from either terminus, but its not halfway UP the mountain! Trains pass the mid ascent mark at 1923ft (586m), well above the travellers’ rest on the Llanberis path.


Tryfan bridge across the Llanberis path near Halfway. The gradient changes slightly here from 1 in 6 to 1 in 6.6. The bridge recieves its name not from the iconic mountain in the Ogwen Valley but from the ridge that lies above the railway © Copyright Gwychder y Wyddfa

The last bridge towards Snowdon’s summit is at Clogwyn, and the second to cross the Llanberis path. Its height at 2562ft (780m) soars nearly 2000ft above the floor of the Llanberis pass. Its often an effective wind tunnel for those walking through it. Nearby was the Valley of the Hats. In the early days the trains had open sided carriages and many railway passengers travelling to Snowdon had the winds at Clogwyn take them by surprise, often resulting in their hats sailing to the depths of the Llanberis pass.


A view of the 1 in 5 gradient bridge at Clogwyn © Copyright Gwychder y Wyddfa

Whilst the bridge at Clogwyn is not the UK’s highest, it certainly is the highest, and oldest, accomodation crossing built in brick/concrete.

Improvement work on the trackbed beyond Clogwyn has resulted in several new culverts which pass beneath the tracks. Other than that the railway closely traverses the contours up to the summit hence no further crossings have been needed. There was originally a bridge intended to carry the Snowdon Ranger path over the railway at Bwlch Glas. However this was not built – hence the SMR’s one and only overbridge failed to materialise.

Comments are closed