Passenger journeys can often be disrupted after major track upgrades as the first week of trains to travel over freshly laid track are forced to do so at restricted speed until the ballast – the stones beneath the track that give support – has settled and formed a solid foundation. Network Rail then has to pay compensation to the train operators for the financial impact of this disruption.
But at Sandy, for the first time in history, an umbilical connected a pair of engineering trains that ran in parallel to simultaneously deliver tamping and dynamic track stabilisation (DTS), which simulated the equivalent of 200 trains passing over the tracks consecutively.
Passenger trains were then able to start using the railway at speeds as high as 125mph as soon as the engineering team had finished because the track and ballast were firmly ‘bedded in’ – which meant Network Rail avoided thousands of pounds in compensation payments.
Above: Track bed at Sandy is consolidated using the Variomatic Bomag roller
It’s estimated that over £5m has already been saved by avoiding compensation payments since the start of the high speed handback programme.
Expanding on those techniques, the work at Sandy was also Network Rail’s first time delivering a high speed handback on a crossing – the most complex part of a switches and crossing layout (the team achieved a high speed handback on a switch in September 2016). The crossing creates a gap in the rail for the train wheel to pass through once the switch – the moving blades that allow the train to switch tracks – have been set.
Track monitoring and installation practices have improved significantly in the last few years. The key to achieving a high speed handback is ‘progressive assurance’ to ensure track is installed at each stage to its specific design tolerances, that care is taken while tamping to get the track to its final exact co-ordinates and that welding is completed as part of the core work rather than scheduled for a later date.
Above: Cutting rail at Acton Wells over Christmas 2015, during the first high speed handback
We monitored the work at Sandy during the weekend and had progressive assurance throughout to make sure we built everything to the highest possible quality levels. This allowed trains to run at 125mph right away – the first time we’ve achieved this on a crossing.
Our high speed handback journey started three years ago. We have been continually improving, systematically getting better at every aspect of what we do.
We have progressively built the knowledge and competence to handback plain line, high output and switches and crossing renewals at 125mph, which will save Network Rail hundreds of thousands of pounds in reduced fees to train operators for disruption caused.
Ultimately this is about passengers. Our new techniques mean we can handback the railway safely, on time and with no speed restrictions meaning passengers get to their destination on time and as planned.
Steve Featherstone, Network Rail’s programme director for track
This improved approach delivers significant benefits for passengers, the workforce, Network Rail, train operators and the millions of taxpayers who help fund the railway:
Faster trains means reduced delays and journey times for passengers.
Staff spend less time trackside as they don’t need to set up and remove speed boards for train drivers.
There’s less need for compensation to train operators as disruption is reduced.