12.02.18
RSSB: Innovative sander configuration could reduce low adhesion delays
Double variable rate sanders could combat leaves on the line, according to new research by the Rail Safety and Standards Board (RSSB).
Sanders are already routinely used to reduce the impact of low adhesion by blasting sand between the wheel and the rail.
Last year, rail services across Britain were delayed by over 350,000 minutes due to low adhesion, causing delays to millions of passengers and freight services.
Reliable braking in these conditions could deliver a significant reduction in industry and wider societal costs associated with low rail adhesion, which are currently valued at over £300m.
The RSSB’s latest research has shown that changing the approach by introducing double variable rate sanders, which automatically apply more sand when braking at higher speeds, dramatically reduces braking distances.
In a three-month programme of track testing in collaboration with industry partners, RSSB created a dataset from over 220 test runs using two new Class 387 trains loaned by Great Western Railway.
The test runs covered various configurations of sanders, test speed and train length.
Multiple and variable rate sanders were found to significantly improve braking compared with the current fixed rate configuration, with two variable rate sanders improving stopping distances on a four-car train by around 50% compared to a single fixed rate sander.
Double variable rate sanders provide add an extra 6% to braking performance, which is an important measure as it is the basis for timetable planning on most routes.
According to the RSSB, using double variable rate sanders can reduce signal passed at danger due to low adhesion conditions by 98%, including low adhesion station overruns by 96%.
By improving the consistency of train braking in low adhesion conditions, RSSB argues that double variable sanders are also a “key enabler” to increasing capacity.
RSSB’s chief executive, Mark Philips, said: “Passengers rightly expect trains to run on time and these results will help operators run a more reliable service regardless of weather conditions.
“Double variable rate sanders will help trains brake better in the autumn when leaves cause problems.
“Having proved the technology, and the benefits, we will now work with the industry to promote the upgrading of sanders to maximise the benefits they can deliver.”
Great Western Railway’s managing director, Mark Hopwood, added: “The ground-breaking results from this testing, using two new GWR Class 387 trains, provide the rail industry with the evidence and clarity it needs to move forward in this challenging area.”
John Edgley, Network Rail’s chair of adhesion working group and chief track and line side engineer, welcomed the research, which improves the industry’s understanding of how poor rail adhesion can be combatted with existing sanding technology.
“This long-standing issue affects millions of passengers each year and often prevents the delivery of the efficient and reliable service they expect,” he commented.
Top image: Emily Norton
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