2016
Grove, Oxfordshire
Network Rail
BAM Rail
Tony Gee & Partners
Great Western Main Line Upgrade Reinforced Soil Solution for Bridge Approach Reconstruction
Sketch view of the approaching Green Terramesh® ramps
The ground investigation identified predominantly soft surrounding soils
Paralink placed over soft soil and wrapped back in an anchor trench
Fourth course of Green Terramesh® being placed on the North ramp
Vegetation is growing on the reinforced ramps
Green Terramesh® ramps vegetated in April 2018
Challenge
The Great Western Main Line (GWML) is one of the oldest and busiest railway lines in the UK, providing a vital transport link between London, the Midlands, the South West, and South Wales. Originally engineered by Isambard Kingdom Brunel in 1833, with the first trains running in 1838, the route remains a cornerstone of the UK rail network.
Today, increasing demand for both passenger and freight transport has driven a £2.8 billion railway upgrade and electrification programme. This major infrastructure project aims to introduce faster, cleaner, and more energy-efficient trains while delivering up to a 20% increase in passenger capacity. However, upgrading a historic rail corridor presents complex engineering challenges, particularly when dealing with ageing infrastructure.
A significant issue was the need to upgrade numerous overbridges along the route, many of which are over 150 years old. These structures were not designed to meet modern loading standards or electrification clearance requirements. Additionally, strict land constraints meant that any reconstruction had to be carried out within the existing embankment footprint, making traditional widening or rebuilding solutions impractical.
Solution
To overcome these challenges, Tony Gee and Partners developed an innovative bridge approach reconstruction solution, with detailed design undertaken by Maccaferri. The proposed strategy involved the complete removal of the existing bridge ramps and the construction of new reinforced soil structures within the original footprint, eliminating the need for additional land acquisition.
After assessing multiple design options, a reinforced soil wall system was selected as the most efficient and cost-effective solution. The design incorporated Maccaferri’s Green Terramesh® system combined with Paragrid geogrid reinforcement, supported by a load transfer platform using Paralink high-strength geosynthetics.
During construction, BAM excavated the existing ramp subgrade to depths of up to 400 mm. A combination of Paralink 400 and 600 grades was installed to improve ground stability and provide enhanced load distribution. This reinforced soil solution increased the overall safety factor and ensured long-term structural stability of the embankments.
The new bridge approach ramps were constructed using the Green Terramesh® system, installed by BAM Rail under Maccaferri’s technical guidance. Modular Green Terramesh® units, reinforced with Paragrid, were installed in a back-to-back configuration to create the opposing faces of the ramps. The finished structures extended approximately 60 metres in length, with base widths ranging from 10 to 14 metres and reaching heights of up to 6 metres.
This reinforced soil solution delivered a sustainable, space-efficient, and durable infrastructure upgrade, meeting the constraints of the site while supporting the wider goals of the GWML electrification project. It also provided a low-carbon alternative to traditional construction methods, aligning with modern rail sustainability objectives.
Used Products
