Highway Embankment Drainage

Starter Layer, Fildrain - M8 Motorway Improvement, Glasgow, UK

Client Transport Scotland

Scottish Roads Partnership

Consultant Amey

Private: Fildrain – Fin Drains




– Significant cost savings
– Rapid installation
– Major environmental savings
– BBA Highways approved

Project Description

The M8 motorway is the principal link between Glasgow and Edinburgh. A seven mile section between Newhouse and Baillieston has remained an ‘A’ class dual carriageway with sub-standard slip roads, considerable congestion, peak time delays and a high accident rate. A major project has been undertaken to upgrade this section of road to three lane motorway standard as part of the same package to improve the junction with the M74/M73, with a value of £415M.

The Challenge

As part of the works, major new embankments were required for the creation of new slip roads and wider carriageways. The road alignment runs parallel to the North Calder Water River and within its flood plain, resulting in a high water table. In order to be able to use locally won materials and speed up the construction of the embankment, a basal embankment drainage starter layer is required. A typical design is the use of a horizontal granular blanket of 6C stone between 300mm and 600mm deep, with a geotextile to either side. This design is costly in terms of materials and installation time. Multiple vehicle movements are required to import the stone and considerable time is required to lay stone at the correct depth, often in very wet conditions.

The Solution

An ABG Fildrain geocomposite was selected as an alternative to a 6C granular material and was shown to have superior hydraulic properties and be robust enough to withstand short and long-term design loadings. The lightweight geocomposite is supplied in rolls up to 4.4m wide, offering rapid installation and significantly reducing vehicle movements and congestion on local roads. Fildrain drainage composite is approved by the BBA as a starter layer in major trunk road applications under embankments up to 12m in height and offers a more cost effective and environmental solution than granular drainage layers.

ABG Fildrain starter layer compared to a traditional 6C starter layer.

  • Benefits include superior hydraulic performance
  • Core prevents re-hydration of sub-layers
  • Placement in one simple operation, no vehicle or site movements
  • BBA approved as a starter layer for motorway embankments up to 12m

Fildrain drainage system is a double cuspated, impermeable HDPE core bonded on both sides to a non woven geotextile, providing drainage to both upper and lower sides. The impermeable core prevents re-hydration of underlying materials during inclement weather.

ABG Fildrain starter layer

The ABG Service

ABG provided full product and design support to aid the approval process.

Contact ABG today to discuss your embankment drainage or starter layer project specific requirements and discover how ABG past experience and innovative products can help.

This scheme is an example of implementing an idea from the Highways England “Managing Down Costs” Toolkit.

Additional information