TRIUR Construction Ltd was delighted to be honoured as winners of the Irish Construction Excellence Award in the ‘Specialist or Specialist Services Contract Over €2 million’ category for their Track Stabilisation (Mini-Piling) project at Lisduff, Co. Laois.
A Silver Award winner in 2020 – the accolade wasn’t presented until last year due to the Covid-19 pandemic – for the Renewal of Coastal Defence Asset ‘Structure C’ at Bray Head, TRIUR Construction has a successful track record when it comes to delivering complex and challenging projects for Iarnród Éireann / Irish Rail. Based in Ballinasloe, Co. Galway, TRIUR is a progressive and innovative specialist civil engineering and building company that delivers high-quality projects safely, on time and within budget.
The Irish Construction Excellence Awards (ICE Awards) are the original and premier recognition of performance excellence for the contracting sector in Ireland, and provide an opportunity for the industry to showcase and reward best practice across the full range of construction disciplines and project categories. This latest award is another feather in the cap of TRIUR which was founded in 2012 by directors Gary Coone, Pat Hartigan and Cathal Coleman, and has grown to employ 90 people. ‘Triúr’ is the Irish for a group of three people, but the company is clearly much more than that now.
“Being a winner in the ICE Awards is great recognition for our company where teamwork is everything,” says Lurcán Donnellan, who project-managed the track stabilisation project on the Dublin-Cork railway line in Division 14, adjacent to the Iarnród Éireann compound at Lisduff. Monitoring data highlighted a number of occurrences of excessive lateral and vertical track movements along this section of track with significant deflection of the existing track arrangements due to the very soft peat layer underneath the track formation layer.
A further soft layer of glacial till was identified underneath this layer of peat during a ground survey. On the ground, while standing a safe distance from the trackside, an observer of a passing train would sense the wave motion in the ground caused by the track deflection. These findings resulted in train speeds through this section being reduced to 80km/h and the need to identify and implement a non-disruptive track stabilisation solution.
Following extensive ground investigation and a rigorous procurement process by Iarnród Éireann, TRIUR was selected to deliver the project before design parameters were prepared and a screw pile system was developed and finalised. Self-supporting end bearing screw piles were to be installed to help transfer the loads from the track to the more stable load-bearing strata found below the peat layer and glacial till. The helices at the top of the pile helped transfer the load from the compacted formation directly beneath the railway sleepers to the more load-bearing strata where the piles met refusal.
A total of 4,937 screw piles were installed with lengths ranging between 2m and 10m as determined by the findings of the ground investigations. The piles were installed between every second railway sleeper at the transition zones located at the start and end of the works area, and between every railway sleeper for the remainder of the works section.
Extensive pile testing was carried out, including static load testing, dynamic load testing and CAPWAP analysis. Detailed records were maintained for each pile, including the pile ID number, design depth, actual depth, pile components used, torque, installation start and finish times, GPS location and pile head depth below sleeper.
Three methods were used to monitor track movement before, during and after the works. A local site coordinate system was surveyed monthly using a total station with 312 individual targets installed at 10m intervals along each rail. Thirty-five void meters were fixed to the tracks before the works commenced which provided continuous readings to a cloud service.
This allowed TRIUR to review the vertical displacement in real time as a train passed over the sensor and provided a comprehensive ‘before-and-after’ analysis of data upon completion of the project. Finally, third-party intermittent interferometric surveys were carried out to provide an independent report verifying the void meter readings.
Typical readings before and after piling works showed comparable results between the void meter results and the interferometric survey results. The void meters measuring the movement of the track relative to the ballast showed a 50% improvement. The interferometric results, measuring the total movement of the track and the ballast relative to a fixed point, showed a 60% improvement across the board in terms of vertical track movement while a train is passing.
Significantly, a noticeable difference can now be felt by an observer safely standing next to the track as a train passes. Instead of feeling the wave motion of the ground, the observer now only feels the level of vibration in the ground that would be expected at any location from a passing train.
The works were executed with no disruption to rail services and in line with all of the approved Method Statements and Risk Assessments which resulted in no Health & Safety incidents. Nightly briefings were carried out with all site team members to reinforce the importance of working safely and to highlight the hazards that could be expected during the night’s work. Feedback from the team allowed for continuous improvements to be made that both reduced exposure to hazards and streamlined the works.
By monitoring the torque resistance of the piles as they reached refusal, TRIUR was able to accurately predict which sufficient embedment was achieved to surpass the design loading of 147kN. A rigorous pile testing regime found that all piles tested received a dynamic load of approximately 300kN without vertical displacement of the pile, surpassing the design parameters.
To summarise, all metrics recorded over the duration of the works demonstrate a significant improvement in the level of deflection of the track. This self-supporting end bearing screw pile design, with a unique pile cap solution, has been proven to work. All possible measures were put in place to ensure the capture of all key data during the project.
The system applied by TRIUR has achieved the desired result of the stabilisation of track sections, whilst eliminating the requirement for disruptive track possessions, simultaneously reducing required maintenance to these previously troublesome areas of track.
“Both Iarnród Éireann and ourselves were very happy with the outcome and we have since commenced two more similar projects for them,” Lurcán explains.
“The physical installation at Lisduff was unique, but we were well set up to do it. The technical side was more difficult, but again we had the necessary expertise. The screw pile system we use is now seen as the go-to-solution for stabilising railway tracks in similar ground conditions across the country.”
TRIUR Construction Ltd
13 Society Street,
Ballinasloe,
Co. Galway
H53 N9X3
Tel: 090 96 44392
Email: [email protected]
Web: www.triurconstruction.com
This article was published in Building Ireland Magazine, July 2023, Vol 9 No 7
