No, I'm talking about magnets that drop onto the rails.
Indeed. I recall when the eddy current brakes were first introduced in Germany, they interfered with axle counter sensors (Germany is where axle counters were invented and they are very widely used there). Engineers solved the problems eventually, no doubt at some considerable cost in time and money.
I doubt these would have much effect at speeds 158s and 159s can achieve! Perhaps a big parachute at the back?!
An eddy current brake, also known as an induction brake, electric brake or electric retarder, is a device used to slow or stop a moving object by dissipating its kinetic energy as heat. Unlike friction brakes, where the drag force that stops the moving object is provided by friction between two surfaces pressed together, the drag force in an eddy current brake is an electromagnetic force between a magnet and a nearby conductive object in relative motion, due to eddy currents induced in the conductor through electromagnetic induction.
Eddy current brake - Wikipedia
en.wikipedia.org
Are you sure they're using composite blocks? Some of our tread brake fleet switched to composite blocks as a trial 15 years ago, the trial wasn't a success and all our tread brake fleet definitely uses cast iron brake blocks to this day.
AFAIK Eddy current braking are only used on a few high speed trains (possibly only the German ICEs)? Magnetic Track Brakes, however, are more common.
The ICE3s and possibly some other Siemens Velaro units alone at the moment apparently, in Europe anyway. Don't know about elsewhere. Although they do pull a vehicle vertically towards the track using magnetic force when under power while stationary, the horizontal retarding force relies on movement so I understand they can't bring a vehicle to a complete stop alone, but they're great for saving brake wear in service braking from high speeds say where regenerative from traction motors may not always be able to provide as much retardation as is required.
Comment was based on past practice on BR Southern Region when they had ubiquitous tread braked passenger train. Admittedly a good few years now.
I'm a member of VT/SIC-ARG (Vehicle Track/Systems Interface Committee - Adhesion Research Group. The cross industry adhesion research group that is funding the trial) so I'm well aware of where it is in the development life cycle and how far away from being a viable product that can be implemented it is. It is still an academic research project to demonstrate proof of concept is sound, there is a long way to go productionise the concept and its implementation and the infrastructure needed.
Up to a point. Regenerative braking is quite common (from the London Underground's "Metadyne" units (O and P stock) to Class 76 electrics to hybrid cars, but they all rely on the motor being used as a brake to slow the rotation of the wheels down (generating electricity which is fed into the external supply or an onboard battery). But they don't prevent wheelslip - if the wheels have locked you will slide. What you need then is something that interacts directly with the track, bypassing the wheels. Retarders, as used in hump yards, are one solution. Ultimately, a buffer stop or sand drag will do the job, but is a bit drastic.
If magnetic systems were only for emergency use, then it may be viable. In real emergency situations, such as this one, to hell with any damage to lineside infrastructure providing it avoided injury or worse.
That‘s only the case in certain countries, usually with fixed signal distances (i.e. Germany). In other countries they are much less common. They can have a significant impact on signalling systems, so they might have to be adapted.
But surely anything which reduces speed is a good thing, even if it doesn't bring the train to a stop; it will make it more manageable and reduce and wheel-slip.
Although in this case, neither train involved was capable of that speed. Also presumably requires a pretty powerful electric power supply to each fitted bogie, so electric transmission on an independently powered vehicle would be required, again probably ruling out any 15x & 16x units as currently configured.
What you describe is a track circuit, and is one of a number of methods of detecting trains on the network. The other main one in use is axle counters, which count a train's axles into a section and out of the section, so would not be affected by sanding. In the event that sanding did interfere with TC detection, you could convert the area to Axle counters. Often if the rails are contaminated enough for wheels to slip they may well be having problems with detecting trains anyway before the sand comes into the equation.
Actually, the track circuit ‘proves’ the absence of a train if the rails are not shorted out by a metal axle and it’s wheels.
It could potentially disrupt signalling track circuits if there was enough of it, over large enough of an area. It can also cause problems with points where it gets on the slide chairs that the switch rails move across and increase the friction, especially if grease/oil has been laid on them too thick causing it to stick. In the worst cases, this can cause a point failure.
Interesting, TY.
All you need is battery power from the carriage. You could use permanent magnets, but that would be a much more complicated design.
