Cleaning contamination from the railhead costs Network Rail around £40m each year, using a fleet of special railhead treatment trains. These trains are highly effective at removing the contamination caused by ‘leaves on the line’, but use vast quantities of water, and have significant maintenance requirements. 

Cryogenic solutions 

Feasibility tests have shown that cryogenic (dry ice) pellets can be used to shock the contaminant layer that forms on rails, causing it to crack and de-bond. Small and full-scale tests have shown that that this approach could be used to improve braking performance.  

Using dry ice could have other benefits: it leaves no residue behind on the rail head and is also non-conductive. This means that it can be used in environments where water-based solutions present obvious safety risks, for example, around equipment with electric, pneumatic, or hydraulic components.   

The University of Sheffield, in partnership with Network Rail, has conducted trials using road-rail vehicles on a selection of passenger lines across the GB rail network. Higher speed trials are planned for autumn 2020 using a research passenger train with Northern; and using a Rail Head Treatment Train with Nexus (Tyne and Wear Metro).  

In 2021, high-speed tests, on the University of Huddersfield’s full-scale test rig HAROLD (Huddersfield Adhesion & Rolling contact Laboratory Dynamics rig), will reach speeds of up to 125mph. 

Plasma energy solutions 

Plasma cleaning involves a targeted high-energy electrical beam, combined with a compressed gas.

Laboratory and field tests have shown that using plasma energy on the railhead can remove layers of railhead contamination effectively, including rust, without damaging the track. The trials have provided valuable insight into the relationship between the power needed to generate the plasma and the speed that vehicles can run during rail treatment.  

This autumn, The Imagination Factory and Network Rail will be trialling a 100kW system on a road to rail lorry, to test speeds up to 45mph. Commercial opportunities have also been identified for track treatment using lower energy levels, mounted on passenger and freight trains. 

To evaluate track conditions before and after plasma cleaning, the Imagination Factory has developed a non-contact, laser-activated system to detect leaf signature compounds. The sensing system will be available as a handheld device for track engineers; and as a trackside monitor for predicting autumnal conditions. The technology will eventually be integrated into the train-borne plasma system to relay feedback to the driver. 

The plasma cleaning and leaf layer sensing technologies have been transferred from The Imagination Factory into a new business, PlasmaTrack Ltd, to enable commercial exploitation.

Find out more

Watch our webinar on innovative rail cleaning technologies includes presentations on cryogenic and plasma solutions, and more.