Loughborough University
Leicestershire, UK
LE11 3TU
+44 (0)1509 222222
Loughborough University

Centre for Innovative and Collaborative Construction Engineering


Theodoros Stylianides

Project Title

Highway Filter Drain Maintenance Management


Balfour Beatty


Dr Matthew Frost
Dr Paul Fleming

Mr Ali El Jaber
Mr Tomasz Klimczak

Director of Research:
Professor Stephen Ison

Research Period

2012 - 2016

Highway Filter Drain Maintenance Management

Company Background

Connect Roads is a subsidiary of Balfour Beatty, the world-class infrastructure services business. Balfour Beatty operates across the infrastructure lifecycle and is the largest company working within the UK highways sector, which includes the PFI market.

Balfour Beatty has four market-leading businesses in professional services, construction services, support services and infrastructure investments. Balfour Beatty Capital is the infrastructure investment business and has committed equity investments of £415 million in 41 projects. It is an equity investor in highways and streetlighting facilities under the UK Private Finance Initiative (PFI) through its Connect Roads business. Connect Roads is one of the UK’s largest private sector road operators which includes five concessions and the M25 London Orbital, via its sister brand Connect Plus.

Connect Roads operates and maintains 360km of trunk road network servicing 2.8bn vehicle km. In partnership with its Term Maintenance subcontractors, Connect Roads undertakes all the operations and maintenance requirements for those routes, and working with its clients, the Highways Agency and Transport Scotland, identifies and delivers improvements focusing on Journey Time reliability and Road Worker/Road User Safety.

Current state-of-the-art

Across a large part of the UK highway network the road carriageways and pavement sub-surface are drained by filter drains. Filter drains are effectively stone filled trenches to depth, fitted with a porous carrier drain at the base to carry water to outfall.

The drains are prone to collecting, at or near the surface, any dust, contamination, vegetation or detritus which is washed or blown off the adjacent carriageway or earthworks. Over time this causes the filter media to block at the near surface or the material to be washed down into the drain further affecting the performance of the media or carrier drain.

Such loss of performance can have detrimental effects on road safety by water ponding across a carriageway at an area of failed drainage, or by water ingress into the road structure leading to reduced pavement life.

Currently there are no overall maintenance systems in place to manage or monitor the performance of filter drains, and typically maintenance is carried out as reactive work (find and fix) or emergency works. Such work normally involves the excavation of the drains and their replacement with new material. Planned maintenance that is undertaken normally tends to be based on empirical evidence or experience of the network with little formal monitoring or long-term planning of works.

Much highway maintenance is now undertaken on a planned and preventative basis (predict and prevent). This is normally undertaken by using regular monitoring of the highway network and recording of issues within a maintenance/asset database and pavement management system frequently linked to Graphical Information Systems (GIS). However the drainage network seldom forms an integral part of these monitoring or management systems.

There currently exists a number of tools and techniques (visual inspection GPR surveys lab tests and sampling) which are used in railway applications to monitor and evaluate the performance and contaminated state of railway track ballast which is a similar material to that used in filter drains. The difference is that railway track beds tend to be wide and relatively shallow. Whereas filter drain trenches are narrow and relatively deep.

Therefore if techniques and systems used in other fields such as those above can be adapted and modified to develop a monitoring and management system for the filter drain network, then its maintenance can be incorporated with the routine pavement management and maintenance systems.

With more planned monitoring more sustainable techniques of preventative maintenance can be developed for filter drains which do not require excavation and replacement, but more reuse, cleaning and minor preventative maintenance work.


The aim of this project it to develop a maintenance evaluation and monitoring system to allow the development of predictive maintenance techniques for highway filter drains.


  • Understand the nature and behaviour of the performance and behaviour of filter drains
  • Develop a system of monitoring and performance investigation tools that can be used to establish and predict filter drain performance and maintenance needs
  • Integrate this system within existing pavement management systems
  • Optimise filter drain maintenance tools to link to the monitoring systems developed

Proposed Research Methods

A detailed study of the issues that affect highway drainage performance

Field studies and investigation of filter drain behaviour and performance.

Investigation in to NDT and innovative investigative sampling techniques both in the field and in the laboratory that can establish filter drain performance (including GPR, visual inspection methods hydraulic tests and sampling) .

Comparisons between the invasive tools and performance observed to enable development of a prediction tool to allow planning of preventative maintenance

Investigation of suitable methods of preventative maintenance.

Expected Benefits and Outcomes

A system that allows the performance of filter drains to be routinely monitored and predictive maintenance to be developed. With the aim of improving filter drain performance and the recycling and sustainable maintenance of filter drain systems. This should reduce costs and road maintenance down time and foster more sustainable use and re-use of materials.

Stylianides, T., et al. 2015. Assessment of highway filter drain fouling and performance considerations. IN: Transportation Research Board (TRB) 94th Annual Meeting 2015, Washington, paper 15-1114, 13pp. https://dspace.lboro.ac.uk/2134/16862



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+44 (0)1509 222623

The Centre Administrator
Loughborough University
LE11 3TU

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