For some of us in rail, low adhesion is a year-round challenge. But, thanks to our Weather Academy, we’re finding ways of delivering a safer, more reliable service during adverse weather, says Network Rail’s Sue Johnson.
RED 66 takes a look at the operational risks around the weather, from the heat of summer to the snows in winter, to the high levels of rainfall that led to tragedy at Carmont in August 2020. Yet for some of us in rail, the autumn, and its impacts on adhesion and braking, occupy the whole year.
As DB Cargo’s Nick Edwards told us in Right Track 35, the problem of autumn adhesion is all about leaves on the line and, more specifically, ‘a combination of the chemical make-up of the leaf itself, the railhead, and how they interact at the point of contact’.
It tends to be the fleshier leaves, like Ash, Sycamore and Horse Chestnut, that contaminate the railhead the most. The railhead is made from carbon steel, which is mainly iron. Iron rusts, and as it does, a chemical reaction occurs with the leaf mulch, resulting in a hard, black contaminant, which gives us our low adhesion risk.
One of the things we have to help us is the rail head treatment train (RHTT). These operate by applying glue-like Sandite or by using a high-pressure water jet to blast the track. But how to target the trains? Dave Shawcross, Network Rail’s Seasons Delivery Manager on the North West route, works closely with the company’s Weather Academy and the train operators. Northern in particular has given access to more of its forward facing CCTV footage, which has been used to pinpoint affected areas. Each area is ranked red, amber or green, with red areas being tackled immediately.
The RHTTs operate in circuits and the ranking determines the speed of the train. The general rule of thumb is 60mph, but this can come down
to 40 in some more tricky areas, to give a more focused ‘blast’. GPS is also used to monitor the RHTT route, and if there are any missed sites (if a train is re-routed, say), the software will pick it up and action can be taken.
‘Working this way helps us find the problem areas more quickly’ says Dave. ‘It will in time take boot miles off the ballast and enable staff to be more proactive with vegetation lineside plans.’
At the start of the season, a close check is made to ensure that the working timetable for RHTT runs doesn’t conflict with planned possessions. ‘We have to balance the adhesion need and the maintenance need,’ Dave explains, ‘but nowadays there isn’t much leeway either side of a possession to get the RHTT in.’
Seasons Delivery Specialist Claire Davies, who works with Dave on the preparation and standards side of the work, adds that the weather is also getting ‘more complicated and harder to predict. This makes collaboration and information sharing all the more important’. With that in mind, TransPennine and Avanti are offering wheel slide protection (WSP) data to shine a light on the adhesion issue from a different angle. Claire says: ‘If we can identify that the WSP alert was caused by contamination, then we can investigate any suitable mitigations.’
‘Our aim is to provide an assurance to ourselves, our users and stakeholders that we’re providing the best available rail head treatment plans available and we have mitigations against those plans if required,’ concludes Dave.
If a driver reports low adhesion to a signaller, a Report of Low Adhesions form needs to be sent to Route Control so the occurrence can be logged and investigated. If the issue was on the approach to a stop signal, level crossing, platform or buffer stops, signallers may be required to caution trains to mitigate the risk.
The weather is getting more complicated and harder to predict, making collaboration and information sharing all the more important.
