Klemm 709 Evo
Piletec’s Geotechnical Role in Rebuilding a Historic Railway Bridge
When Network Rail embarked on the reconstruction of a 150-year-old bridge in Looe, Piletec was trusted to engineer the deep foundations that would support its future. Working under intense time pressures, environmental restrictions, and limited access, our team combined technical precision with innovative problem solving to complete the piling works safely, efficiently, and on schedule.
Project Overview
Piletec were engaged by Sisk Rail to deliver the specialist piling works for Network Rail’s reconstruction of a 150-year-old railway bridge, located on a remote, single-line track near Looe. The project formed part of a critical infrastructure upgrade aimed at preserving the structural integrity and operational safety of the historic rail line, which serves both local communities and seasonal tourism.
Due to the bridge’s age and location, the works presented numerous logistical and engineering challenges. Site access was highly restricted, requiring careful coordination of plant, equipment, and materials via both rail and road. The piling scope involved installing deep foundations with strict tolerances and alignment requirements, given the proximity of existing track infrastructure and sensitive environmental conditions.
Where It All Began First Steps on Site with Our Partners
“From concept to completion with contractor insight guiding the way.”
Piletec led the piling phase, assigning a specialist team to install ten cased and bored in-situ reinforced concrete piles. These were constructed behind the existing abutments during staged weekend rail blockades, in line with the client’s design. Our early involvement and technical expertise enabled seamless integration with the wider programme, supporting Sisk and Network Rail through operational planning and design acceptance.
We collaborated closely with AECOM (Principal Designer) and ECUS (Environmental Consultant), ensuring compliance with all regulatory bodies including the Marine Maritime Organisation (MMO), Natural England, and the Environment Agency.
Collaborative Delivery and Problem Solving
From the outset, Piletec played a key role in delivering this complex rail infrastructure project. Despite challenges such as variable ground conditions, restricted access, evolving design requirements, and environmental constraints, our team maintained programme momentum through a proactive, collaborative approach.
Working alongside Network Rail, AECOM, we implemented practical and innovative solutions that ensured the works were completed safely, efficiently, and within extremely tight possession timescales.
This achievement highlights Piletec’s proven ability to deliver under pressure, providing dependable, high-quality outcomes across the most demanding rail environments.
Built for Power, Made for Rail
Numa’s Super Jaws 508mm OD Overburden System
Our custom built Klemm 709 EVO-remote, mounted to a Rail RRV, is a serious piece of kit. Purpose-built for rail infrastructure works, this setup combines raw drilling power with the mobility and stability of a rail compatible platform perfect for tough environments and tight schedules.
Foundation Engineering
Each pile was constructed using heavy duty, segmental steel casings, installed to a depth of 15 metres. The casings were threaded together via steel collars and filet welded during installation, ensuring full structural continuity and alignment. Once the casing was in place, a 4-metre rock socket was drilled beneath, allowing the pile to be anchored into competent bedrock. This sequence was critical to the structural design, as the casing itself was incorporated into the permanent load bearing system, providing enhanced tensile capacity and long term durability in a highly constrained and geotechnically complex environment.
Whether it’s weekend blockades, restricted access, or demanding ground conditions, this rig delivers high performance drilling exactly where it’s needed. Fast, reliable, and built to get the job done.
Failure to protect the work and respect the time invested
After a full weekend of drilling, we had successfully completed the first stage of a complex pile installation part of a two weekend operation to finish a single pile. But when we returned for the second blockade, we discovered the borehole had been backfilled with ballast during site cleanup by other contractors. the backfill was also contaminated with steel and timber, making recovery even more difficult.This unexpected action wiped out the progress made during the initial 32- hour shift, undoing hours of hard work and preparation. It’s a clear example of how vital communication and coordination are on multi-phase infrastructure projects.
The weather was rarely on our side wet, windy, and cold but we didn’t let it stop us.
The setup was demanding both in logistics and performance. The compressors had to run in sync to deliver the airflow needed for efficient drilling through tough ground conditions. Mobilising the system in winter added complexity:
“Working in partnership with Stratum Drilling Solutions, Piletec employed specialist Down-the-Hole (DTH) equipment that delivered consistent performance and accuracy across the piling package.”
We pumped concrete over 200 metres across the salt marsh to reach the pile locations. The setup required careful planning hoses laid out across soft, uneven ground, constant monitoring of flow rate, and coordination between the pump crew and the pile team. The marsh conditions made access difficult, but the system held up well, and the pours were completed cleanly and efficiently.
The Team Behind The Success
Challenges Faced The project presented significant constraints:
- A 42-degree slew of the bridge
- A location overlaying a tidal canal, flanked by a fast-flowing river and adjacent to an environmentally sensitive salt marsh
- Remote access, with the nearest Road Rail Vehicle entry point over an hour away
- During piling, significant design issues were uncovered. Although Piletec were not contractually responsible for design, we proactively supported AECOM with innovative solutions. Our expertise collaboration were instrumental in resolving these challenges.
- Innovative Pile Design Solutions
- During detailed design, AECOM identified that the original pile diameter was insufficient to accommodate the required reinforcement in the top 8m. PILETEC stepped in to support the design process, organising workshops and developing a solution suitable for the complex site conditions.We proposed a composite design using the steel casings originally intended for temporary ground support as part of the permanent structure. This approach provided additional tensile capacity and structural integrity, especially considering corrosion over the bridge’s 120-year design life. A novel pile casing over-collar was engineered to reinforce joints and ensure long-term durability.
Strong foundations, smarter planning Piletec’s expertise in pile installation made the Looe project a success.
The bridge replacement had to be completed within the strict timescales of a pre-defined railway blockade. To reduce risk and ensure delivery confidence, we developed a detailed hourly blockade programme, mapping out the sequence and duration of every activity. Regular planning meetings with Network Rail allowed us to interrogate the programme in minute detail, giving the client confidence that the track would be handed back on time.
Flood Mitigation
The bridge overlies a tidal canal, the water level of which ranges by approximately 3m in height depending on tide. In addition, the adjacent salt marsh is on the flood plain and can flood by approximately 1m during high spring tides. The tidal conditions of the site have had a significant influence on the installation methodology and have been a significant project risk, of which several mitigations and contingencies were planned.
We organised contingencies to mitigate the effect of site flooding. For example, the thermal lances to burn the pile casings would not work if the excavation was under water. We developed innovative bespoke aluminium cofferdams. Should the excavation become inundated, we would place these cofferdams around each pile to provide a dry area to burn the steel casings.
Piling Possessions
10nr reinforced concrete piled foundations were installed underneath the track in phases during multiple 32-hour long weekend possessions using modified road rail vehicles. We produced a bespoke temporary works design which used steel caping plates over the pile casings to protect them and provide safe passage of trains above.
Pile Cropping
We would first excavate behind the abutments during the main rail blockade to expose the previously installed piles. However, as the piles are steel encased, we could not crop them down by conventional means, and had to first burn off the steel casings. We organised extensive trials to find the best method and determine exactly how long it would take burn the pile casings and crop the concrete piles on site. We developed an innovative method of first weld lifting points to the casings, before burning into sections using a thermal lance. Once completed, these sections were lifted out using chains.
Bridge Replacement
Following the Pile Cropping, Piletec were responsible for grouting the bridge beams into position, ensuring a secure, void-free connection between the superstructure and substructure. All works were delivered within the tight rail possession windows and in full compliance with project specifications and safety requirements. Through close collaboration and effective planning, Piletec helped ensure the smooth and timely delivery of a key stage in the bridge replacement programme, contributing to the successful completion of this vital infrastructure upgrade.
Piletec took full responsibility for sourcing, supplying, and expertly installing the whaling beams, creating a robust, interconnected pile system that ensured structural stability and long-term performance during the bridge works.
The whaling beams, grit blasted and coated for corrosion protection and extended service life, incorporated a custom splicing detail that ensured seamless connection and optimal load transfer between individual sections.
Return To Full Railway Operations
Back on Track: Successful Reopening of the Railway
The project reached its final milestone with the safe and timely reopening of the railway line, marking the successful completion of this critical infrastructure upgrade. Restoring this vital transport link was a key objective for the client, and its return to service has re-established essential connections for passengers, communities, and local businesses. Thanks to close collaboration, careful planning, and Piletec’s specialist expertise throughout the works, the bridge replacement was delivered seamlessly and on schedule. The line is now back in full operation, providing a reliable and resilient service for many years to come.