Phase 4: Rhyd Ddu to Porthmadog

The Nanmor and Dylif River Bridges

Phase 4 pages:
Beddgelert: Bridges & Station
Nanmor & Dylif Bridges

Recent updates are underlined and in red.

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The route section of the site includes detailed illustrated descriptions - Rhyd Ddu to Beddgelert and Beddgelert to Porthmadog.

Almost immediately south of Hafod y Llyn Isaf the railway swings towards the East, and runs across flat, open farmland reclaimed from the Traeth Mawr saltings when the Cob was built across the Glaslyn. The two main features of this stretch are two river bridges crossing tributaries of the Glaslyn, the Afon Nanmor (UB196) and Afon Dylif (UB199); Hafod Garregog halt lay between them. If the halt is ever reinstated, the railway has undertaken to use the current spelling, Hafod Garegog.

These structures were truss bridges identical in design and dimensions to that at Bryn y Felin, although the details of the abutments varied according to the location. Although in a less dangerous condition than the old Bryn y Felin bridge, the steel structures suffered from the same problems - they had never been painted, or modified to allow rainwater to drain away properly - and were demolished shortly after the acquisition of the trackbed in 1999, at the insistence of the railway's insurers. Part of one of the Afon Nanmor trusses was left on site for later display as a historical item.

The contract for their replacement was let to D.J. Williams and Son of Caernarfon in October 2005, and their fabrication and installation followed on from the structure at Bryn y Felin. Like that bridge, the Nanmor and Dylif ones look very similar to the originals, but are much stronger, and properly protected from the elements.

UB196: Afon Nanmor

Just as at Bryn y Felin, an artifical 1 in 150 gradient has been created across each bridge to help rainwater drain from the steel channels of the trusses. This was done by adding a new cap to the concrete structure of the abutment on the one side of each watercourse, raising it by six inches. The pictures below show the Afon Nanmor site in December 2005 after this work had been done by specialist contractors.

The site is seen below in February 2006, with the remaining section of one of the original trusses visible.

The pictures below show the site almost a year later, soon before installation of the bridges was due to start. The last two pictures show original phosphor bronze bearing plates on the abutment on the Porthmadog side.

Between the Bridges

From the Afon Nanmor the trackbed runs straight, crossing a couple of culverts, to the site of the old halt, adjacent to occupation crossing LC105. The rails which acted as posts for the nameboard remain. The line curves gently right through the halt, and straightens again to reach the Dylif.

UB199: Afon Dylif

The more southerly of the two bridges was the first to be installed. There is no practical road access to the remote locations of these two bridges, so they were brought in along the trackbed from the south.

The picture below is looking down chainage across the Afon Dylif on January 21st 2007, with the Nanmor crossing in the distance. Surveyor's posts were in place along the stretch between the two bridge sites.

The site is seen below in early February 2007, soon before reinstatement of the bridge itself began; the last picture shows the trackbed beyond the bridge, at an advanced stage of preparation for delivery of the structure.

Building the Bridges

The structures are seen below at the manufacturer's premises in Caernarfon on October 6th 2006, with one bridge test assembled, and the trusses of the other at an advanced stage of fabrication.

Both bridges are seen on the left below on February 1st 2007, with the Dylif bridge in the foreground. They are not completely identical, as the Nanmor bridge has an external footpath walkway cantilevered from one side; this can be seen on the left in the second picture.

Installing UB199

The Dylif bridge was delivered from Caernarfon on Saturday February 17th 2007, with the basic structure of end transoms and side trusses assembled on site the same day. Unlike the operation with the identical bridge at Bryn y Felin in March 2006, the trusses had to be brought to site individually rather than as a pair, as they could not be brought all the way on metalled roads. The trusses were brought in as planned from the Ynysfor access along the trackbed, via the new wider radius curve past Croesor Junction. Two cranes were used, with the one used on the riverbank specially lightened by 15 tonnes and brought to site via the Carreg Hylldrem access. The abutments had been fitted with locating studs for the transoms shortly before, and the fittings of the original bearing pads had been refurbished.

The lorry had to reverse back down the trackbed before making its return trip to Caernarfon for the second truss, which was lowered into place and secured as evening fell.

The next day, Brunswick staff were at work fitting the intermediate crossmembers, waybeams and bracing pieces.

Preparing for UB196

UB199 was fitted with its timber deck within the next two days, so that the civil engineering contractors could access the trackbed to the Afon Nanmor bridge. The "green" section from UB199 to LC105 was scraped down to the old ballast by February 21st, prior to laying stone.

The views below show UB199 on March 1st 2007, with the construction company Land Rover standing on the trackbed on the side leading towards LC105; the last view is looking the other way, up chainage towards Croesor Junction.

The track of the crane was slightly wider than the timber deck of UB199, so Brunswick Ironworks fabricated temporary deck infill panels to be placed either side (where the walkways would later go) to give the necessary support; this was an amendment to an initial plan to use lengths of rail, and had the advantage that the beams are lighter and could be relocated subsequently for use at Bryn y Felin. The pictures below show these beams in place for dumpers moving stone from temporary stockpiles on the new Croesor Junction curve to make up the trackbed to LC105.

When seen below, tree clearance was taking place in preparation for installation of the bridge, which required making up an area of hard standing for the lorry and crane.

The ground at the immediate approach to the bridge was quite eroded. The picture below shows the spot on March 10th 2007, with the bridge site indicated by the gate in the background.

It had been considered that the section from LC105 to the bridge approach, which had been in use as an unmade roadway, was already in adequate condition to carry the crane and lorry; in the event it was decided to lay stone through this section, and this work is seen in progress below on March 8th and 13th 2007.

The crane was moved to the site on Friday March 16th 2007, and is seen below crossing UB199; the crane was reversing, as there was no space to turn it at the Afon Nanmor site, and the turret needed to be adjacent to the river.

Installing UB196

Unlike UB199, the trusses for UB196 came as a single lorry load; the southern truss was delivered with the external walkway structure and handrail already assembled, making it the heaviest single item to be lifted into place in the whole river bridge programme. The trusses were loaded up at Brunswick Ironworks on the morning of Saturday March 17th 2007, and taken to the site via the access south of Ynysfor. UB199 was crossed at walking pace, with about 200mm to spare on either side.

Transoms, waybeams and other components were already on site at the Afon Nanmor. A rescue boat was placed on the stream, which is deep (3.5m) at this point. The south truss was put in place first.

The lighter north truss followed, completing the basic structure of the bridge.

The walkway panels were then fitted, giving pedestrian access across the span. The last picture shows the new structure with the preserved section of the old one in the foreground.

The transoms, waybeams and bracing were fitted on Sunday March 18th.

Following the installation of UB196, a new access roadway to Ynysferlas farm was created immediately to the south of the trackbed, which had been serving this purpose previously.

Completion Works, Winter 2007-8

At the start of December 2007, G.H. James Cyf were in the process of moving from the contract stretch north of UB196 to complete the trackbed from UB196 to LC112. On December 4th, they were making up the formation on both sides of UB196.

This view shows a drainage ditch up chainage of UB196, which had been opened up to help drain surface water from the area immediately adjacent to the trackbed and the new roadway to Ynysferlas.

With the deck plates back in place on UB199 (first used on this bridge and then at Bryn y Felin) to gain vehicular access from the work base south of Ynysfor, James's early priorities include culverting work a short distance up chainage of UB196, and completion of the new roadway to Ynysferlas, which still required a short section separate from the trackbed at its end.

These pictures taken on December 14th 2007 show this work in progress, plus (left) new foundations for the gabion retaining wall at UB196 which will also give pedestrian access to the walkway, and (right) excavation for pipework at a previously unidentified culvert between drainage culvert UB198 and LC105.

On December 18th 2007 James's staff were installing gabions at UB196, and digging a cess between the trackbed and the new roadway.

These pictures show UB199 and the stretch between it and LC105 on the same day.

By December 21st 2007 UB196 had been fitted with its timber deck (to which rails would be fixed in the same manner as at Bryn y Felin), and the southern approach to the bridge was close to finished, including the retaining wall and the earth bank alongside it.

The contractors resumed work on January 7th 2008, and ballasted the first few hundred metres from UB196 that week, allowing tracklaying to proceed. The trackbed between UB196 and LC105 was very close to ready for sub-base before New Year, needing little more than a small amount of extra fill at culverts forming part of the improved drainage system. The new roadway to Ynysferlas had been made up to the entrance to the property, curving away from the railway close to UB196; the Head of Steel had reached just short of the far side of the bridge the day before these pictures were taken (the rails visible on the bridge were not yet fixed down or connected up).

A similar set of improved drainage measures were in hand at and beyond LC105; contractors' vehicles are visible in the distance in the first picture, making use of the area of hard standing created for the crane when UB199 was installed.

Newly-laid sub-base is seen on the formation up chainage of UB196 and heading for LC105 on January 8th 2008.

Approximately 250m of ballast was laid starting from UB196 on January 10th 2008, and more was laid the following day, reaching LC105. James then laid out sleeper bundles from the roadway, as seen in the distance in the first of these pictures.

Sub-base had been laid through the old Hafod Garegog halt site when pictured on January 15th 2008.

On the morning of January 22nd 2008 sub-base was being rolled on the approach to the Afon Dylif bridge, and ballast was likely to reach the bridge by the end of the day.

This view from January 24th 2008 shows ballast and sleeper bundles at Hafod Garegog, extending all the way to the Dylif bridge in the background.


On January 3rd 2008 a small ballast retaining wall was being built on the western side of UB196, to allow tracklaying to proceed on to the bridge.

The Black Hand Gang screwed the rails down on the bridge and connected them up to the track to the north over the weekend of January 5-6th, as well as carrying out some alignment work down chainage of the bridge.

The following weekend the Rest of the World Gang started by completing the alignment work on the Hafod y Llyn side of the bridge, and then proceeded with laying track leading off the bridge on the Porthmadog side.

After the above pictures taken on Saturday January 12th 2008, Sunday's tracklaying saw another seven panels laid despite gale force winds and rain. The Black Hand Gang took the Head of Steel most of the way to LC105 the following weekend.

Work was being done to fit gates at either end of the UB196 public walkway on January 25th 2008.

UB196 had been fitted with its guard rails outside the running rails by February 6th 2008.

Saturday January 26th 2008 saw fourteen panels laid by the Rest of the World Gang strengthened by the Imperial College Railway Society and the FR Dee & Mersey Group; this broke the previous daily record which had stood for several years, and was done despite rails having to be moved manually using RRMs over some 500m, as Upnor was not allowed across UB196. This effort took the Head of Steel through LC105 and the old halt at Hafod Garegog. Fencing had been erected between the railway and the Ynysferlas roadway (first picture).

The weekend's total was twenty-one-and-a-half panels - another new record - reaching a point 18m short of UB199 (one panel had been left half-completed at the end of the previous weekend's work owing to a shortage of rail). As at the other river bridges, it was necessary to stop at this point as the procedure would be to lay rails on the bridge and measure back from there. With the contractor's work done down chainage of the Dylif, the plates for road vehicles had been removed from the bridge, which would allow the walkways to be fitted. Excavation had been done adjacent to the abutment on the Porthmadog side of the bridge for a retaining wall to be added, as had been done at UB196.

A week later, the gabion retaining wall had been added on the Porthmadog side of UB199, and preparations were visible for James Cyf to build a ballast retaining wall at right angles to the track, like those at UB196. The timbers had been temporily removed from the bridge, for a little attention to be paid to it before tracklaying.

Brunswick Ironworks arrived on site on February 4th 2008 to rectify minor painting defects incurred during transport and cranage of the bridge. Once the dirt that had accumulated while the bridge was used by road vehicles had been scrubbed off, the paintwork was found to be in very good order, with only minor blemishes needing attention prior to fixing the timber deck permanently in place. The work was complete by the end of the week, after which Ray Jarvis added the ballast retaining wall on the Beddgelert side.

James Cyf are seen at work on the trackbed on the Croesor Junction side of the bridge on February 6th 2008.

Two days later the paintwork had not quite been completed, but it was done in time to put the timber deck permanently back in place the next morning. Ballast was being laid on the far side.

With the deck in place and the walkways fitted, the Head of Steel was extended on to the bridge (and out of the National Park) on February 9th 2008. Rail movements were supported by the loaned Lister diesel delivered to Hafod Garegog the day before, and Upnor Castle was also now working up chainage of the Nanmor bridge, with the three ballast hopper wagons.

These pictures were taken on February 10th 2008, the day when tracklaying reached the far side of UB199 and entered the sections covered by the Afon Dylif - Pont Croesor page.

The Tuesday Gang visited this area on July 29th 2008 to erect posts for signage. Six were put up at LC105, and four at LC106, just on the far side of Dylif bridge, where the Gang are pictured below.

Erection of the signs themselves, again by the Tuesday Gang, began on August 12th 2008 at LC104 (near the Afon Nanmor) and LC106. This style of smaller bilingual "Stop, Look, Listen" sign is known as Type 2 in the nomenclature of the various signs needed on Phase 4, and it is thought that these were the first Type 2 signs to be put in place.

Over the weekend of August 16-17th 2008 the Black Hand Gang replaced wooden sleepers with steel at LC104 and LC106. It was noted that the name "Pont Ynys Ferlas" had been adopted for UB196, replacing "Pont Afon Nanmor".

The following pictures were taken on September 24th 2008.

HMRI has determined that check rails are not in fact necessary at UB196; they were therefore lifted over the weekend of June 20th-21st 2009.

Maintaining the Operating Railway

The Tuesday Gang were in action at LC103 and LC105 on this section installing horse handles' on the the gates. Both these crossings are bridleways so require these facilities. 

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Maintained by Ben Fisher; last updated July 15th, 2010 by Laurence Armstrong