Case study: High Output Ballast Cleaning System – Reducing Ballast Waste on Britain’s Rail Network

Ballast is the graded stone sub-base that forms the track bed upon which railway sleepers are laid. Its function is to support the track and aid drainage. After twenty years on the infrastructure, ballast needs to be renewed. The track itself is designed to last for forty years, but it is Network Rail’s High Output team’s responsibility to regularly clean the ballast without replacing the whole track.

Company - Network Rail, Infrastructure Projects Track

Due to the high volume (and cost) of ballast, Network Rail aims to reuse as much of it as possible, reducing virgin material used.

How was this solved?

Since 2005, Network Rail has been operating a High Output Ballast Cleaning System (HOBCS).

The Ballast Cleaning System works by excavating ballast from beneath the track while holding the track in position. The machine passes the excavated material through large vibrating sieves, removing damaged ballast, before returning the larger pieces of ballast to the track. Finally, the machine then adds new ballast to make up for that removed.

The HOBCS has allowed us to reuse approximately 2.6 million tonnes of ballast over the past 10 years (as at 2017), providing both environmental and economic benefits.

What were the outcomes?

Reducing ballast waste is helping us to deliver our organisations sustainable development objectives. These include: zero waste to landfill, reducing carbon emissions and optimising resource consumption.

Specific project achievements are:

  • Recycling materials and reducing the amount of ballast waste – ballast cleaners avoid the unnecessary disposal of reusable ballast, which is on average 40% of that excavated. Over the past 10 years, the HOBCS has allowed us to reuse approximately 2.6 million tonnes of ballast.
  • Reducing embedded carbon emissions through a reduction in purchasing virgin materials.
  • Minimising financial costs - £9 million in material savings compared with conventional methods of removing old ballast.


  • Reducing our environmental impact
  • Customer Driven

Organisation type

  • Network Rail

Log in or register to keep reading
Register for free individual access
  • Unlock research, articles and more
  • Get updates on RSSB’s activities





Need some help?
To talk to us about accessing RSSB content or corporate membership:
Cookies help us improve your website experience.
By using our website, you agree to our use of cookies.