The Bleach Green Railway Viaducts and the “Loop”

(or it’s hard to get people out of Belfast)

Belfast Hills horseshoe from Redburn Country Park

Belfast is a city built at the end of a coastal inlet and surrounded by hills. Like many coastal cities, shipbuilding and sea travel feature large in its history and sense of identity. However, the surrounding hills, which played a key role in shaping its development, are strangely neglected.

Perhaps this is because historically they were seen as an impediment, a boggy wall of poor agricultural land blocking travel and access to the rich hinterland of Antrim and Ballymena.

Even today the hills are mainly inaccessible with only about 7 miles of the the total 32 miles of potential skyline walk accessible to the public (my calculations).

Modern Belfast with its hills, lough and rivers (including the Farset where it all began)

The hills certainly defined and restricted the growth of Belfast as you can see from this modern map. A particular problem was transport – again the hills continue to constrain and shape our highways and byways.

A modern road map shows that for all our engineering prowess – the hills still dominate.

The First Railway to Ballymena

Now what is true for road builders in the 21st century was most certainly true for the Victorian railway pioneers. Particularly because there are two things railways don’t do well – go up steep hills and go around sharp corners!

In 1839 the first Belfast Railway took the easy and lucrative option of heading straight down the gentle gradients of the Lagan Valley to the wealthy linen town of Lisburn and the prosperous fertile valleys beyond. Initially it terminated at Portadown, but was then extended to Armagh.

The Linen Industry in and around Ballymena and Antrim was also thriving. There was a demand for a new railway to serve this area and no shortage of private investors keen to fund it. The Belfast and Ballymena Railway Company was formed with the aim of realising this scheme. However, the Belfast Hills provided a formidable barrier. There was fanciful talk of a tunnel under Cave Hill and a suggestion of avoiding the problem altogether by starting from Lisburn instead and going the long way around via Crumlin! The problem of the Belfast Hills seemed too difficult.

What was needed was a practical “man with a plan”. So the Belfast and Ballymena Railway Company engaged the services of Charles Lanyon, the go-to Belfast Victorian for big projects. Whether you wanted a gothic college, an outsized conservatory, a spectacular coastal highway or a trunk road through a bog – Charles Lanyon and Co could deliver and with style. Lanyon and his surveyor, Robert Young, soon came up with a solution to overcome the Belfast Hills and build a railway to Ballymena and beyond.

Lanyon’s Belfast – Ballymena Line solution zig-zagged at “Carrickfergus Junction” to beat the hills.

Good Try – but Could Do Better

Like most good solutions it was simple – if a bit of a cheat! Lanyon couldn’t resort to the road builders’ standard hairpin bends to zig-zag a route up a steep gradient so he simply joined two diagonally climbing railways together with a set of points. The first section climbed to 166 feet above sea level to Carrickfergus Junction (now Greenisland Station). The second line ran from Carrickfergus Junction past Ballynure Road Station Station at 320 feet above sea level. The elephant was eaten in two equal bites!

The lower new station was called Carrickfergus Junction, emphasising that the line onward to Carrickfergus was very much a minor branch line of the much more important Belfast Ballymena Railway.

The only drawback to the plan was that the train would have to “reverse” up the second stage all the way to Ballymena! To make this practical the engine had to decouple from the train at Carrickfergus Junction, move onto a siding, reverse to a turntable, the turntable be rotated through 180 degrees, the engine drive forward past the train onto the Ballymena line and then reverse and recouple onto the train!

This slow and labour intensive process was recognised as something which should be done away with if possible in future and the idea of a “loop line” to achieve this was conceived.

Cutting the Corner

It took 90 years for the idea of the loop to become reality. The original Belfast Ballymena line was funded by private investors eager to tap into the wealth of the Linen Industry, but the upgrade in the 1930s was largely paid for from the public purse as a relief scheme to ease the chronic unemployment of the time.

Map showing the new planned route out, up and onward to Ballymena

You can see from the map above this scheme would reduce the journey to Ballymena slightly, but much more importantly the need to reverse the train would be removed and twenty to twenty five minutes would be saved.  Also the substantial staffing costs would be reduced as there would no longer be a team of men needed at Greenisland to reverse the trains.

Building the Line (and the Viaducts)

Building the new climbing, curving line with major embankments and cuttings was a major engineering project in itself, but the greatest challenge was the construction of two massive reinforced concrete viaducts. For their time these represented cutting edge technology and construction techniques very different from the tried and tested ones used in the existing stone viaduct they were to sit alongside. Built by unskilled labourers from the local community – who were supervised by railway engineers unfamiliar with the use of large scale reinforced concrete – it was an amazing achievement by all involved.

The elegant, almost airy arches of the loop bridge carrying the line to Ballymena

Why did the loop line take so long to be realised when the benefits were so clear? Well, the engineering needed was anything but “plain sailing” – this was a complex problem in three dimensional design, where the railway had to curve and climb simultaneously at rates near to possible limits over a river valley requiring viaducts. The existing Lanyon viaduct at Bleach Green was too low and too near Greenisland, The loop would have to start its climb (and curve) well below, crossing the Three Mile Water valley. It would need its own new viaduct. More difficult to understand, the line onward to Carrickfergus and Larne was not able to cross over the loop line and proceed as before. Instead it had to drop down to the left, follow a new path over the Three Mile Water requiring a third viaduct before rejoining the path of the Larne Line. Only the returning line from Larne to Belfast would now be carried on the original Lanyon viaduct. Hence the spectacular interweaving triple viaduct you see today. At the time of building this was the largest reinforced concrete railway viaduct in the British Isles.

Technically this arrangement is known as a burrowing or flying junction. From below as the walker passes through, the flying junction term seems much more appropriate!

The “Flying” Bleach Green Junction. Drawing based on a diagram from Currie J R L The Northern Counties Railway Volume 2

Designed in the 1930s there is a definite Art Deco feel about these structures. They are futuristic, light and indeed optimistic. Architecturally Belfast tends to feel Victorian, solid, rather heavy and not very adventurous. It therefore seems appropriate that in contrast these cutting edge bridges should embrace the new style so successfully.

Note the Art Deco detail on the vertical piers
Construction drawing shows the foundation masts, and suspended chute lines. Also shown is one of the girder arches used to support the wooden “forms” which the concrete was poured into from the chute lines above.

The construction progress largely consisted of pouring concrete into hollow “forms” – wooden moulds which defined the required shape of the bridge sections. At many points the wooden joints in the forms left marks in the concrete and these were deliberately left to add detail and break up the flat areas of concrete.

The six steel arches’ support slots are clearly visible in each of the major viaduct pillars

A final feature of the construction process is still clearly visible in the photograph above. As you can see in the construction diagram, the wooden forms which defined the great arches required support from steel girder arches. These temporary arches in turn were supported by sitting on six slots moulded into each of the bridges’ uprights. These groups of wedge shaped slots were left unfilled, providing subtle and appropriate decoration to the final work.

The two 1930’s concrete viaducts framed by original Lanyon bridge, walker and NIR Train

What’s in a Name?

There is remaining the question of the name – why call a steep sided glen site “Bleach Green”. The answer lies to just to the south and parallel to the glen, where a large industrial works, based around the Linen Industry, extended for three quarters of a mile parallel to the Three Mile Water river. A mill race ran from just below Monkstown to feed the chain of mill ponds and factories. The Bleach Green Works must have dominated the area – both in terms of employment opportunities and environmental impact!

Much of the old works was still visible until the late twentieth century after which it was built over with housing

Even in industrially depressed 1935 these works were still very active. The junction included a railway siding for the mills and a new Bleach Green Station platform was built on the Larne line.

Mossley West Station?

Despite the embankments and Bleach Green Viaducts, the loop line still could not climb fast enough to get up to the old Mossley Station. The engineers’ final trick was to lower Mossley Station down to meet the railway in a new deep cutting! They also moved it 700m along the line towards Antrim and the setting sun – renaming it Mossley West!

If you have used Mossley West Station and ever wondered about its odd name and its almost subterranean setting – now you know!


In 1978 the loop line and the rest of the railway to Antrim was closed to passenger traffic as part of a “modernisation” of the Northern Ireland Railways Service. Subsequent to this, all trains to the North West would run from the new Belfast Central Station (named after the old Central Line railway, not because it was near the city centre – it wasn’t) via Lisburn over a branch line through Crumlin to Antrim – a 30 mile route rather than the existing 19 miles via the Bleach Green line! The “new” route was the same one the Belfast and Ballymena Railway Company had rejected in 1844 as much too long and inefficient!

Amazingly, little used as it was, the route survived until 1994 when happily a new rail link bridge was opened across the Lagan linking Central Station (which was recently renamed Lanyon Place) to the old York Road Terminus. Trains once again ran from Belfast via the Bleach Green Line to Antrim, Ballymena and the North West.

The Belfast Rail Network as it is today

There is an ironic footnote to the transition from trains reversing at Greenisland Junction to the streamlined flow on the loop line. Modern NIR trains have a driver’s cab at each end enabling the train to reverse by the simple action of the driver walking from one end to the other. Had the loop line not been built, trains could have reversed today at Greenisland up the old “back line” with ease. However, then we would have all lost out on the much more elegant solution of the loop line and the wonderful Bleach Green Viaducts.

Getting There

There is no car park, or indeed road access, immediately adjacent to the viaducts so you have a choice of how to approach them. If travelling by train, walking from Whiteabbey (1.7km) or Jordanstown (2.7km) halts are options.

The obvious car park option is Loughshore Park (1.8km) where there is also a cafe. My preferred option however is the Woodland Trust car park on the Monkstown Road (1.4km). This way you approach the Viaducts downhill through the very attractive Monkstown Wood and the first glimpse of the great concrete arches from this direction is quite something.

All the distances above are for a one way journey. In the case of the Monkstown Wood car park, there is an option to vary your return route using the map to add more interest and distance.

Associated Walks

The Bleach Green Viaducts feature in my Carnmoney Hill Seashore Circuit. At over 11 miles and with considerable climb this is a challenging walk. However, the Mossley West Station to Bleach Green Viaducts sub section will give you all the details for Monkstown Wood, through the Viaducts, the Glen and onto the seashore.

Maps to Download and Print (PDFs)

Please feel free to reuse these maps for your own projects, honouring the terms of the OpenStreetmap licence:

External Links

  • Greenisland Viaducts – Classic Travel Poster by Norman Wilkinson. On sale from the Yard Gallery, Holywood
  • Travelogue of Northern Ireland, 1930’s Huntley Film Archive – features Viaducts


  • Currie J R L 1973 The Northern Counties Railway Volume 1 1845-1903 David & Charles : Newton Abbot
  • Currie J R L 1974 The Northern Counties Railway Volume 2 1903-1972 David & Charles : Newton Abbot
  • M’Ilmoyle R L 1933, “Reinforced Concrete Railway Viaducts Near Belfast”, The Structural Engineer Nov 1933 pp. 430-443
  • Public Records Office NI (PRONI) OSNI Historical Map Viewer