Part 3, Operational Trials
In November 2017 (issue 157), Rail Engineer reported on trials undertaken at the Rail Innovation and Development Centre, Melton of multiple variable rate sanders fitted to a GWR class 387 EMU, with the expectation that service brake performance would be significantly improved in poor adhesion conditions.
Then, in May 2018 (issue 163), Rail Engineer reported on a seminar held by RSSB to present the results of those tests. They reported that 6% G deceleration could be achieved, even in very poor adhesion conditions. At the end of that seminar, RSSB appealed to members to volunteer to help them take the project forward.
Rolling forward to October 2019, at the invitation of RSSB’s Aaron Barrett and Paul Gray, Rail Engineer arrived at Redditch station – one end of the Birmingham Cross-City line – to witness further tests that were carried out over several Sundays in October 2019 and to learn what had happened since 2017/8.
West Midlands Trains, the operator trading though the West Midlands Railway and London NorthWestern Railway brands, had volunteered to work with RSSB as they were particularly keen to improve the reliability of the Cross-City line, where, as operations director Mark Steward explained, there are significant leaf fall problems from trees on third-party property. WMT routinely implements an autumn timetable, which slows the trains and harms punctuality.
Since Autumn 2018, enhanced adhesion performance data has been collated and analysed on the Cross-City Line, including additional train traction/braking monitoring equipment on Class 323 units. Although this has provided further insight into the effectiveness of the various low-adhesion treatments, only limited results were obtained as the drivers drove mostly in step 1, the lowest brake rate, and provoked little WSP (wheel-slide protection) activity.
Undaunted, two units have been equipped with variable rate sanders, a) to replace the fixed rate sanders dispensing on the third axle in the direction of travel and b) additionally to apply sand under the seventh axle of these three-car units. A further change since the original tests is that sander operation is now automatic in response to the train WSP equipment.
Test set up
The purpose of the test was two-fold. Firstly, to ensure that the performance of the improved sanders on the Class 323 was at least as good as that on the previous trial, and secondly, but most importantly, to enable WMT drivers and health and safety representatives to experience how the system works and to be able to use higher brake rates, steps 2 and 3, with confidence.
Arrangements were quite similar to those for the 2017 tests, except for the site and the rolling stock. Despite a very strong desire not to disrupt passenger services, all concerned saw the benefit of demonstrating the system to drivers who would operate the trains on infrastructure that they drive every day – hence the Redditch site.
In summary, paper tape was applied onto the running rails over a length of approximately 750 metres. The tape was wetted with train-mounted water sprays to provide the low adhesion conditions, and the train was then run over the tape for two out-and-back moves to bed the tape in.
Then several runs were carried out, braking from 55mph without sanding to condition the rails before a step 1 brake was used to demonstrate slide at a low brake rate and thus poor adhesion. Finally braking runs with sand in steps 2 and 3 were demonstrated.
One of the safety control measures was to lower the pantograph before entering the paper tape zone and not raise it again until the train had coasted off the tape. This measure ensured that there were no adverse effects from possible poor traction return paths whilst on the paper tape; a lesson learned from the 2017 tests.
Another precaution was the provision of a temporary additional compressed air tank. This provided a reserve of compressed air whilst the pantograph was down and the compressor out of action.
To illustrate the effect of the enhanced sanding, a step 3 brake with no sand only managed to reduce speed from 55 miles/hour to 40 miles/hour by the end of the paper tape (a speed reduction of 15 miles/hour over the 750 metres travelled).
Once the enhanced sanders were activated for a repeat test, the brake application was so successful that the brakes had to be released early because there was barely enough momentum left to coast to the end of the paper tape so that the pantograph could be raised again. Your author was in conversation with Parvaiz Elahi, the ASLEF health and safety representative, during the step 3 test with sand and we were both suitably impressed.
A further innovation was the method of controlling the possession. Network Rail’s operational sponsor and organiser of the tests, Dominic Mottram, said this is a comparatively unusual Signal Protection Zone, where both incursion into and out of the possession is controlled solely by signals held at danger. Whilst SPZs are not a new concept to the railway, the success and positive reaction to their implementation for this project has already attracted attention from other parts of Network Rail.
Dominic added that this project was a team approach with Network Rail, RSSB, West Midlands Trains, DB ESG, Ricardo Rail playing leading roles and with a very important stakeholder in the form of the West Midlands Rail Executive.
What follows are the impressions from the day; RSSB will publish formal results in due course.
Mark Steward of West Midlands Trains told Rail Engineer that the test objective – building driver confidence when driving relatively normally on contaminated track – had been delivered. He said that the next step is to introduce the two units into passenger service. Mark was aiming to use experienced drivers on these modified units, and to compare their performance with the performance of the trains in front and behind using ‘big data’ analysis techniques to assess performance in service.
He added that, as this is an experiment, he recognises that there will be a risk of station over-runs when driving this way, and will manage that risk appropriately, both for safety of the railway and for driver competence management, such that drivers will not be penalised if they are driving modified units on contaminated track using the techniques tested.
He added that he had not been prepared to authorise the trial unless he was confident it was safe and his visit was partly to gain that confidence.
Drivers, their representatives, and their managers were most impressed with the system. If this autumn’s service trial is successful, it is to be hoped that the system will be fitted to many more trains over the next few years.
Thanks to Paul Gray (RSSB), Mark Steward (West Midlands Trains), Dominic Mottram (Network Rail), Andrew Lightoller (DB ESG) and Liam Purcell (Ricardo Rail) for their assistance with this article.