FFU: the sustainable choice at Dublin Heuston

Nigel Keightly

The Sekisui Chemical Company has manufactured synthetic wooden products made from Fibre-reinforced Foamed Urethane (FFU) since 1980.  First introduced on Japanese Railways 44 years ago, early installations of the product are still performing to specification. FFU is now widely used on railway infrastructure in 33 countries to support track on bridges, decking for level crossings, plain line sleepers, and Points and Crossing (P&C) bearers.

In July 2017, Iarnród Éireann (Irish Rail) engineers installed the first FFU baulks on the 135-metre-long Shannon River Bridge at Limerick. Since then, FFU has been used to provide track support for several other railway bridges and P&C projects across Ireland.

Background

Developed in conjunction with Japanese National Railways, FFU synthetic sleepers are made using a pultrusion process. Continuous glass fibres are soaked and mixed with polyurethane, and then hardened at a raised temperature, moulded, pulled and cut to length. This creates a high-quality material that has the life expectancy of plastic and the weight of natural wood, which can be worked like natural wood.

First installed in Japan in 1980, and adopted for standard sleepers and turnout sleepers, FFU has subsequently been installed on numerous projects in Europe over the past 20 years, particularly turnouts and bridges. Up to the end of 2023, there was more than 2,100km of track with FFU sleepers around the world.

Tests of the original 1980 sleepers undertaken by the Railway Technical Research Institute in 2011 predicted that the FFU sleepers could safely continue in use for another 20 years, giving a total life of at least 50 years.

Dublin Heuston

Over the weekend of 26-27 October 2024, Irish Rail installed its latest P&C layout utilising FFU bearers. It was a busy weekend for delivery teams and contractors as they renewed the double slips and switch diamond panels, HN766, HN765A, HN765B, and HN764 at Heuston Station in Dublin. The programme of works was 18 months in the planning but delivered in a 57-hour possession, without incident, and on time for the planned possession hand back time.

The new double slips and diamond switch panels were manufactured in Nottingham by Progress Rail. Sekisui was incredibly pleased that Irish Rail had specified FFU as the bearer system to support Progress Rail’s design. The FFU bearers were manufactured in Sekisui’s factory in Roermond, Netherlands, during early July, and shipped to Nottingham to be pre-built with the ironwork into panels, before shipping on to Dublin ready for installation.

Work started in the early hours of Saturday 26 October with the removal of the life-expired double slips and diamond switch panels, before a full formation dig by RRV. The bottom ballast was then graded with a dozer and compacted to predetermined levels by Bomag roller.

With the formation works completed, Irish Rail used its Kirow Crane to commence the installation of the new double slips and diamond switch panels. Following the completion of the installation works, ballast was backfilled ahead of OTM T751. Hot works were completed before the worksite was fully handed over to signalling and electrical engineering colleagues to complete the commissioning works. The T3 possession was successfully handed back to operations at 08:22 on Monday 28 October, slightly ahead of its 09:00 planned hand back deadline.

Sekisui was delighted to be chosen to supply its FFU bearers for this project by Irish Rail, thus building on the success of other recent P&C renewals in the Dublin area at Malahide and Dun Laoghaire.

Liam Hickey, infrastructure manager, Dublin, at Irish Rail said: “We were keen to include Sekisui FFU as part of the Progress Rail layout at Dublin Heuston Station. FFU will contribute to a better and more reliable asset for this heavily used key artery in and out of Dublin City, giving a better experience to our customers.

“Track access at this location is difficult, we considered that FFU offered better resilience to the environment and with a significant life expectancy over 50 years, we believe it will contribute to reduced maintenance intervention and lower costs for decades to come.”

Points and crossing assets

The P&C assets in question – namely the Heuston double slips (HN766 and HN764) and the Heuston switch diamonds (HN765A and HN765B) – serve Platforms 4 and 5 of Dublin’s Heuston Station. Installed as part of the station’s extensive redevelopment between 2000 and 2002, these assets were integral to the upgrade that transformed Heuston Station from a five-platform terminal to a major transit hub with eight platforms and a significant increase in track capacity. This redevelopment was driven by the need to accommodate more passengers and services, as well as to future-proof the station’s design to allow for potential structural developments above the yard.

In planning the initial upgrade, designers faced the challenge of preserving track space across the front of Platforms 3, 4, and 5 while optimising accessibility to accommodate increased train movements. The decision to install double slips and switch diamonds was a strategic one, allowing maximum flexibility and minimal spatial use – an essential factor given the high volume of train movements. Over the past 22 years, these bi-directional assets have supported an average of 178 train movements daily, equivalent to approximately 33,000 tonnes, which has led to significant wear and tear.

Necessity of renewal

Following joint inspections by the chief civil engineer (CCE) Infrastructure Maintenance (IM) teams and the Signalling and Electric teams, it became evident that the assets had reached a critical threshold. Maintenance alone could no longer sustain operational safety, and a full renewal was essential to prevent potential catastrophic failure. This finding initiated the planning process, starting with a series of site meetings and coordination sessions to strategise the renewal.

The first site meeting in April 2023 included key stakeholders such as the regional manager, divisional engineer, senior track and structure engineer, divisional permanent way inspector (PWI), signalling supervisor, and senior assistant engineer from the Production team. During these meetings, the Project team reviewed existing layouts and identified areas for potential adjustments to improve post-installation maintenance efficiency.

The team’s engagement with Progress Rail, a key supplier for the project, facilitated the integration of insights from both the CCE/IM and signalling departments, which proved invaluable in refining the design approach. From here, planning progressed toward securing a possession map that would allow for daytime work while enabling the continuation of passenger operations on unaffected platforms. Collaboration with the Infrastructure Manager (IM) Safety team, the IM Operations team, and railway undertaking colleagues was crucial in finalising Possession Map HN/STN/1.

Systems testing

Once the possession map was established, a series of system tests were conducted with participation from the Signalling and Electric team, IM Operations team, and the Signalling Cabin at Heuston. These tests ensured that all interlocking systems would function safely during the work period and verified safe traffic operations around the affected track areas. Periodic meetings allowed the team to closely monitor progress, ensuring that each aspect of the system met safety and operational targets.

In parallel, the CCE/IM team began the procurement process for essential equipment, which also included tendering and securing the required Rail-Road Vehicles (RRV) along with coordinating with our Production colleagues to secure the Kirow Crane T900 and the OTM P&C Tamper T751, both critical for executing the track panel replacement and ballast work. After finalising logistics, the project’s delivery window was scheduled for the October Bank Holiday weekend, a period chosen to minimise passenger disruption.

Delivery and assembly

In Week 42 (the week of 14 October 2024), the first two track panels arrived at Heuston’s goods yard from the Progress Rail yard in Nottingham. Transported by ferry and offloaded by the Kirow Crane T900, these initial panels were positioned for installation. While logistical issues delayed the remaining three panels into Week 43, the team’s advance preparation allowed the Signalling and Electric teams to assemble back drives and stretcher bars on the delivered panels, setting the stage for installation.

Once all panels were delivered, the Division 2 CCE/IM team arranged them sequentially to streamline the installation process, ensuring that each panel would be available in the correct order for the scheduled work on the October Bank Holiday weekend.

Renewal works

Renewal work commenced with the granting of the extended T3 Possession (IE/HN/2) at 00:45 on the morning of Saturday 26 October, which was later adjusted to HN/STN/1 at 05:56. The Tamper and Kirow Crane were stationed on Platform 4 by 01:30, after which the disconnection of old panels and initial burning work began. Panel removal proceeded efficiently, with all old panels removed by 03:30 and relocated to a designated storage area.

Excavation began shortly after, achieving a full 300mm depth by 04:00, followed by backfilling and grading. By 07:30, backfilling was underway, and the formation was rolled in preparation for the new panels. The installation of the five new panels – comprising a crossing panel, HN766, HN765A, HN765B, HN764, and another crossing panel – proceeded with precision, facilitated by the Kirow Crane.

As each panel was positioned, insulated block joints and fish-plated joints were secured, with specific joints earmarked for welding and clamping by 21:00. Ballast backfilling followed, and OTM T751 completed double or triple tamping where necessary, with hand-packing performed in areas inaccessible to the tamper.

Commissioning and handover

Upon completion of the track and ballast work, the site was cleared of all RRV plant and equipment, and the worksite was prepared for the Signalling and Electric team to conduct system testing and point commissioning. This phase included rigorous testing to ensure that the new P&C assets integrated seamlessly with Heuston’s existing interlocking systems, ensuring safety and operational readiness.
The project concluded with the successful handover of T3 Possession at 08:22 on Monday 28 October, just in time for the arrival of the Waterford-Dublin passenger service on Platform 4. This marked the official reopening of the platform, which now operated with the renewed P&C layout, encompassing HN766, HN765A, HN765B, and HN764, and positioned Heuston Station for continued reliable service.

Outcome and impact

The completion of this renewal closed out 45 senior track and structure engineer notifications, underscoring the project’s role in improving asset reliability and safety. The collaborative approach among Civil Engineering, Infrastructure Maintenance, Signalling, and Rail Operations teams proved essential to the project’s success, demonstrating a commitment to high standards and passenger safety. With these assets renewed, Heuston Station can continue to meet the demands of heavy train traffic with improved resilience and reduced maintenance requirements for years to come.

Sekisui would like to give thanks to Liam Hickey and Martin Hewitt for their contribution to this article.

Irish Rail would like to thank all its staff who worked hard to make the project a success, along with its contractors and suppliers; Breffni Group, McCormack Plant, Romberg Sersa, GPX Rail and Progress Rail.

This article is dedicated to Declan Conlon a valued Irish Rail chief civil engineer team member who sadly passed away on 16 October 2024.

Image credit: Sekisui