Browney Curve Landslide
Browney Curve is located 3 miles south of Durham and carries two electrified tracks on an up to 12m high embankment crossing sidelong ground above the River Browney. Since problematic ground and groundwater conditions were encountered during construction in 1872, Browney Curve has been affected by unstable ground due to a complex system of landslides.
Despite several attempts to stabilise the ground, primarily through the control of groundwater and river realignment, instability has persisted, and embankments have shifted up to 2 metres both vertically and horizontally since 1986. This movement has increased the need for track maintenance, drainage repairs, and adjustments to overhead line equipment, leading to higher maintenance costs.
As a result, Network Rail required a permanent ground stabilisation solution to be developed for the site. Pell Frischmann was appointed to investigate the drainage system and propose solutions to limit ground movement at the site.
About this project
Location
County Durham
Sector
What we did
The Browney Curve project developed a stabilisation solution for the large and complex landslide system, which had been disrupting rail traffic on the East Coast Main Line (ECML) for 150 years.
The initiative addressed two significant landslide systems threatening the ECML. Landslide 1 was a deep-seated compound slip system extending up to 15 metres in depth and affecting 500 metres of rail embankment. Landslide 2, on the other hand, was a shallower slip system that impacts hillside groundwater flow and presents complex geotechnical challenges. The site is characterised by a repeating sequence of glacial till, glaciolacustrine, and glaciofluvial deposits, which include laminated sand, silt, and clay.
Ground investigation carried out in 2017 together with archive data for the site collected over the previous 147 years amounting to some 320 exploratory holes was used to develop a ground and groundwater model and determine the location of shear surfaces around and within the railway embankment and the landslide system.
The landslide stabilisation element of the project was initiated in October 2023 and completed in January 2025.
Key interventions included:
- Bored Piles: Installation of 529 bored piles (23-25m long, 750-880mm diameter) to stabilise the slope.
- Automated slope and track monitoring
- Drainage Improvements: Enhancements to slope and deep drainage systems, including protective sheet piles.
- Ecological Solutions: Tree planting along the riverbank to reduce erosion and improve stability at the toe.
Outcomes
Shortly before mobilisation to the site, the design of the pile reinforcement was reconsidered due to the high cost and scarcity of steel. The solution was to use repurposed ‘non-prime’ steel from the oilfield industry, which was more easily accessible. This resulted in a reduction in construction costs and time, and a higher sustainability score for the project.
The early procurement of various ‘non-prime’ CHS steel sections and the optimisation of their placement across the site during the design phase significantly contributed to carbon reduction and cost savings. By positioning the lower pile rows closer to the riverbank, it was possible to implement tree planting to stabilise the bank, minimising erosion at the toe of Landslide 1. The project team from Pell Frischmann, Network Rail, Story Contracting, and Keller had previous experience working together on other rail earthworks schemes, allowing the seamless completion of the project and stabilisation of the Browney Curve.
By understanding the specific ground risks, the complexity of the landslide, and its effects on the movements of the East Coast Main Line (ECML), coupled with a collaborative approach, we were able to effectively demonstrate and assure Network Rail’s operations teams of the efficacy of our risk mitigation strategies in real time.
Awards
We are delighted to share that the stabilisation of a large landslide impacting the East Coast Main Line Embankment at Browney Curve has been shortlisted for this year’s Ground Engineering Awards 2025 in the UK Project with a Geotechnical Value Over £3M category.
On being shortlisted for the award, Head of Geotechnical Engineering, Andrew Gill, said:
“It’s fantastic for Pell Frischmann to be recognised for the great work of the team since first being involved at the Browney Curve site in 2013. This is the largest landslide stabilisation project of its kind undertaken for Network Rail, and seeing its successful delivery is a testament to the talent of our team and the collaborative efforts of all involved.”
