The Snowdon Mountain Railway is a narrow gauge rack and pinion railway in the UK and winds through spectacular scenery to take visitors the 4.7miles from Llanberis to the 1,085m Summit of Snowdon, the highest mountain in Wales.

In 1894, work began on the construction of the Snowdon Mountain Railway. It had taken over 20 years to get to this point, after local opposition from the landowner, Mr Assheton-Smith, was finally lifted. 

The first five steam locomotives were ordered from Switzerland, where they had expertise in carrying passengers up and down a mountainside. Three of these are still in operation today, which is testament to the quality of their original manufacture. 

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Construction began with the engineers for the railway, Sir Douglas Fox and Mr Andrew Fox alongside the contractors, Holme and King of Liverpool who were to build the Llanberis and Waterfall Viaducts that cross the Afon Hwch river. Within a year, over 50% of the earthworks were completed and track laying began from the Llanberis base and working upwards, to ensure the correct alignment of the rack. With the trains already delivered, they were pressed into action to deliver men and materials to the moving construction site and by January 1896, the first trains reached the summit. 

The final construction cost £63,800 (equivalent to around £7.5m today) and the grand opening was scheduled for Easter 1896. Sadly, there was an accident on the opening day and it was delayed. The subsequent enquiry concluded that post construction settlement, combined with the weight of the train and passengers was the problem. They further recommended, that going forward, trains could only run at around 75% capacity. This prompted the design and introduction of new lighter carriages for the service.

In 1986, ninety years after the original steam trains entered service, two diesel locomotives were added to the fleet. They were equipped with 320hp Turbocharged Rolls Royce Engines and cost £250,000 each. They proved so reliable that three more were added over the next four years. Soon after their introduction, the Diesel engines took on the large majority of the passenger journeys. On an average running day today, the diesels make 16 journeys to the summit and the steam four. It’s so popular that they run seven days a week.

A plan for new carriages

For as long as it’s been carrying passengers, weight has always been the limiting factor on the running capacity of the railway. So, in 2011, when Garmendale took the first call from Mike Robertshaw, the Senior Engineering Manager at Snowdon Mountain Railway, it was with a brief to create new, lighter carriages for the diesel rolling stock. 

For ease of implementation, a decision had been made to work with the bogies made by Hunslett, as their braking systems and bogies had already been signed off for use on the track. This would save over two years on the delivery of the completed carriages, so was a great shortcut. 

One year on and the new carriages were delivered to Snowdon in October 2013 for their maiden voyage. 

The new carriage design used a revolutionary lightweight material, designed to save weight and create a warm insulated carriage for comfort, with huge glass areas for visibility and wide opening doors for ease of passenger access. 

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Soon after the project was completed, Mike Robertshaw, recapped on the how the project had run from his perspective. 

“Until 2013 the carriages had been in service since 1896. They had twice been re-bodied in house during 1951 and 1957 and were past their useful life. 

We issued the final specification in 2011 and two compliant bids were received. One bid proposed an aluminium bodied carriage and the other from Garmendale, a novel GRP honeycomb body. Both options used a development of the latest braking technology from Hunslet Engine Company on their bogies. 

Building the new Snowdon Mountain Railway carriages

After several months of review and discussions with the tenderers it was decided to work with Garmendale. They would build the chassis and bodies, including fit-out of the carriage interior and external livery. The bogies and braking system were to be provided to Garmendale by Hunslet. 

The GRP honeycomb body was felt to have maintenance advantage as well as inherent insulation properties and provide a corrosion free structure that would be important in the conditions in which it would have to operate.

We carried out an extensive engineering review and although the approach was novel and the materials untried in railway vehicle manufacture, Garmendale provided test pieces, demonstrated fabrication techniques and the final paint finish, all before the contract was finally placed. 

During the design phase, weight of the new carriages was a major consideration as the new carriage would potentially be heavier than the existing stock. The Garmendale solution actually reduced the weight of the carriages, whilst increasing passenger capacity.”

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By way of an update, we went back to Snowdon and spoke to Mike Robertshaw to see how the project had been from his perspective and how the carriages are faring after six years and around 750,000 passenger journeys. 

“We knew the team at Garmendale from their work at The Needles on the chairlift. They are our sister company within Heritage Attractions and we knew their engineering was strong and we could work with them.

Garmendale proposed using a honeycomb board they had been testing. We went to see a company that had been using it to make van bodies and it looked like a good solution. 

The brief we set was to create a carriage that was capable of carrying up to 70 passengers. The existing ones could take 56, so this increase in capacity would make the journey more comfortable for passengers whilst also allowing us to run more efficiently.

They actually delivered us a bigger weight saving than we expected – over 3,000kg – which allowed us to carry up to 74 people in each journey. Like our friends at Ironbridge Gorge we’ve noticed the weight of passengers having an impact and we have since reduced the capacity back down to 60 people per journey. This could have been more challenging for us financially, but with some better load balancing and scheduling on our part, we do generally run all of the trains at near capacity.

The steam trains are still incredibly popular, but the diesels take the bulk of the load. Some of the consumer research we did, showed that an awful lot of people just want a ‘taxi to the top’ rather than the full steam experience. Since we separated the diesel and steam services, the demand for the steam has gone up, but they are incredibly expensive to run and maintain so we have to treat them with care.”

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The second order

The success of the new carriages prompted a second order the following year to upgrade the heritage carriages too, as the new carriages aren’t compatible with the steam engines. Mike continues

“For the new heritage carriages, Garmendale again worked with supplied Hunslett Chassis. We commissioned them in 2014 and the year after the new carriages were delivered. They also came with a re-engineered handbrake system. The new design was created from original photos and some original drawings. Structurally, they were much stronger. Following on from this, in 2016, they delivered a second replacement heritage carriage.”

So the real question for us as engineers is ‘how have they been in their first six years in service?’ and Mike again has the answer.

“They have met all of our expectations. They are very low maintenance and the body has coped perfectly.”

Having seen the carriages in the flesh, six years after entering service, we can also say that they look pretty much as good as new. For us, this only confirms the novel approach of Garmendale was the right approach – even if it was untested at the time.

In order to understand the project from a Garmendale perspective, we interviewed David Shelmerdine, Managing Director of Garmendale Engineering.

“It was one of those marquee projects for us. Loads of history and incredibly high profile, so we had to get it right first time. In the conditions the Snowdon Mountain Railway operates, there’s just no margin for error. You can see all four seasons in an hour up at the top, let alone a day. 

We’d been looking at the honeycomb panels for a little while and knew there was a project around the corner that it would suit. 

And then this project walked in the door. 

There were other honeycomb products out there but none that were built to this specification, where the top and bottom of the material were bonded at the time of production, rather than being added afterwards as a strengthener. We had to go to Germany to find it, but it was worth the effort. 

We knew that an aluminium body and steel chassis would create huge problems with heat expansion and be a nightmare for both the maintenance and longevity going forwards, We felt quite confident going in to talk to Snowdon about our new material, even though it was an untried product in rail applications. We just knew we could make it would work. 

Six years on and the proof is in the pudding, as they have performed exactly as we expected.”

We also spoke to Chris Hurt, the Lead Engineer on the project from Garmendale and he remembers the project very clearly too. 

“The brief was for a lighter, lower maintenance carriage that could hold more people and we worked hard to achieve that. The Polypropylene Honeycomb panel we selected for the body gave us the incredibly light weight we were looking for with the potential for the structural rigidity we needed and the durability that the conditions at the top of Snowdon demanded. But there were a lot of challenges in the design, not least the terrain and the track itself. 

One of the first jobs was to push a loading gauge up the track and see where the most stress was created. This uncovered a few things we weren’t expecting, with tighter corners on some particularly steep bits, which fed directly into the design. We’ve often been asked why the design for the carriages had a tapered rear end and the answer is that this came directly from the loading gauge run. Tapering it minimised the clearance overhang and ensured the engine wasn’t ever in the situation where it was fighting a losing battle with the carriages on tight corners.

In order to manufacture the very fluidly shaped body from the flat panels, we first created full sized cutting jigs to make up the correct radius for each of the panels. There were only four body panels in total – The two sides, the floor and the roof, plus the nosecone.

Separate cutting jigs were made for the windows and doors to ensure a perfect fit when the windows were added.

We then created full sized assembly jigs for the whole body and it was built up and plastic welded. The nose cone had a steel flange that was bonded into the overall structure.  The body was then rotated through 180 degrees and an inner roof bonded in place as well. This gave the overall structure, incredible strength.

More amazingly, when it was fully built up with the seats in place too, but before the windows and doors, it only weighed 750kg. 

The doors were added after this and had been made up from a combination of two section aluminium and a light steel skeleton inside the inner door. 

Overall, it was an engineers dream. Full of challenges and a project to be proud of. It’s one I’m delighted with to be honest. “


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At over 120 years old, the Snowdon Mountain Railway already has a huge history behind it. The work the Garmendale Engineering team undertook in creating the new carriages has set it up for the next chapter in its long history. If you’re ever lucky enough to be in Llanberis at the foot of Snowdon, pop in and say hello, take your taxi to the top of Snowdon or enjoy the heritage steam route, or maybe even work up a sweat by walking. Whichever route you choose, think of the team in Ilkeston, Derbyshire at Garmendale that helped to get you there in style, comfort and warmth. 


The journey to the top on the Snowdon Mountain Railway

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