Solving the railway capacity problem in five years
1 The engineering problem to be solved
Railway train wheels have a poor grip on steel tracks, compared with rubber tyres on roads. This severely reduces the ability of trains to brake rapidly during an emergency.
For example, at 80 miles/hour, the braking distance for an eight carriage passenger train is sixteen times the braking distance for a car travelling along a dry road at the same speed.
To meet an increased demand on the national railway network, we can either
(a) Stick with our Victorian era friction braking systems and build more tracks to increase capacity. - This is the HS2 approach.
(b) Employ a powerful frictionless braking system that will allow more trains to travel safely along our exiting tracks. This would allow the whole of the UK to benefit from improved rail communications.
The powerful brakes we need are are already up and running in Germany. They are called eddy current brakes.
If you want to skip the technical details, scroll down to
Section Four, A Summary of comparative costs
2 How the improved British braking system will work
In addition to existing brake systems, each carriage will be fitted with eddy current brakes that automatically slow the train down if a dead man’s switch is operated. Permanent magnets that drop down into their operating positions during emergency braking can be used. But we will describe an electromagnet option because electromagnets are more powerful and can be used for routine braking as well.
We recommend that the new “braking rails” are made from iron, so that the track is ready for running Magtrac trains at a future date.
Figure 1. For routine braking, the electromagnets can be powered by an onboard generator. But for maximum protection, backup batteries would be provided. Each magnet would be serviced by its own battery.
The total braking contribution made by the eddy current brakes increases with the number of magnets.
Sufficient magnets could be added (for example), so that, with 50% redundancy, the train carrying capacity of the line could be doubled without compromising braking safety.
the rails clean
Time will be required to lay the iron rails and build new
rolling stock fitted with eddy current brakes.
4 Summary of comparative costs
Q. Is it possible to draw off the electric currents generated during normal train braking?
brushes could be used to complete an electrical circuit between
batteries on the moving train and the iron rails. In essence the system would
become a linear version of a Faraday Disk. To improve efficiency, the
electromagnets would be placed in linear arrays. (Several weaker magnets would
replace each powerful magnet.)
This current capturing feature is a green energy bonus, but not an essential for powerful braking.
Additional braking safety measures
The looming environmental disaster posed by HS2
HS2 will act as a migration valve, sucking people into the south.
Commuting from the North where house prices are relatively low to the capital where salaries are high makes financial sense. But commuting from expensive accommodation in London to lower paid jobs in the north would be slightly bonkers.
As northerners tire of their daily journey, feel the pain of the HS2 train fares and build up friendships in the south they will be motivated to move there. This will increase pressures on the green belt making the Chilterns and other desirable areas of the south into commuter suburbs for London. This in turn will lead to calls for new motorways and roads in the south.
Carbon footprint implications
HS2 is bad news
Fuel consumed doing work against air resistance increases with the speed of
the train raised to the power of three. This means that increasing average top
speeds from 125 miler per hour to 225 miles per hour increases the carbon
footprint per passenger for a similar sized train by a factor of 5.8. [
5.8 = (225/125)3 ]
Eddy current braking is good news
Increasing the United Kingdom railway capacity by reducing
the braking distance for trains will take far more drivers off the roads than a
single new route that connects a few English cities.
Which option would Isambard Kingdom Brunel and our Victorian forefathers have chosen?
The North of England needs to improve the capacity of its railway network across the whole of the region within the next ten years. If we have to wait three decades for a limited improvement between Manchester and Leeds very few of today's commuters will benefit.
Building on the investment made in installing the iron rails
If the electromagnets used for eddy current braking are replaced with a more advanced design of electromagnet, a whole new railway traction and braking system becomes possible. We refer to this as Magtrac.
Magtrac offers the following advanced features:
(ii) A Transport Internet
The improved network capacity offered by eddy current braking and Magtrac systems will open up new possibilities for moving battery powered cars piggyback on trains. This will make battery powered motoring affordable to more drivers because electric vehicles will be able to travel long distances, without the expense and weight of massive onboard batteries.
One of this article we will explain how Magtrac technology works.
In Part Two we explain how Britain could lead the world in creating a Transport Internet.
In the Appendix we reveal how a radically new design of power generator could be used to produce liquid hydrogen fuel for Magtrac trains. The UK Technology Strategy Board and EPSRC have jointly awarded us £93,400 to build a prototype generator according to this design.
Part One - Magtrac
Figure 2. Maglev is an engineering marvel, but very expensive to build.
Magtrac is simpler and cheaper than Maglev.
are suspended under the train and interact with soft iron rails mounted on the
existing railway track sleepers.
The braking and acceleration benefits of Maglev are maintained, but Magtrc’s levitation effect is not sufficient to support the weight of the train.
Figure 3, Magtrac.
Q. Why are iron rails required instead of
1 HOW IT WORKS
The solenoids become electromagnets and either mutually attract or repel, depending on their polarities.
Figure 4. In
addition to attraction or repulsion between the two solenoids, each solenoid
experiences a repulsive force between itself and the enclosed soft iron bar.
This provides a small levitation effect.
of conservation of energy has to be respected so we do not get "free" energy out
of either of these arrangements. For example in Fig. 3 (a), after the solenoids
have moved together, work has to be done against the magnetic attraction, to
restore the magnets to their original positions.
1.2 A load carrying platform
Figure 5. To move a lightweight platform along a short length of track, the soft iron bar needs to be bent into a U shape.
1.3 A practical traction unit
For the platform to move along a track of indefinite length:
long chain of U shaped iron bars is required.
Figure 6. The platform and supporting half solenoids can move along an indefinite length of track
Figure 7. This is a “half solenoid”, with all of the windings connected in parallel. When an electric current flows through the windings, a magnetic field similar to a full solenoid is produced. But its asymmetry results in a net upward force when it rests on a soft iron bar.
Figure 8. An alternative, series winding. The neutralising effect of the upper half solenoid is minimal, because of its greater distance from the soft iron rail.
Figure 9. Further
details of the electromagnetic coupling.
We will refer to the activated half solenoids as runners and the lengths of soft iron tracks as stators.
It is not necessary for the runners to be in close contact with the stators and large clearances between them are possible to avoid fouling by small items of debris. (Large clearance gaps require large diameter half solenoids. So the total length of conducting wires generating the magnetic flux increases, compensating for the larger air gap.)
Large clearances will allow wipers to be added, to periodically clean the under surfaces of the runners.
The conducting wires can be made from superconducting material and the half solenoids immersed in very cold chambers protected by Dewar insulation.
engineers will recognise that some technical details relating to back EMFs,
current changes and the fate of kinetic energy lost during emergency Magtrac
braking have been omitted. Nor has the configuration for regenerative
Magtrac braking been revealed.
1.4 Explanation: Why the size of the air gap, ice and leaves on the rails do not affect performance
The only downside of a large air gap is that the half solenoids are slightly bulkier, heavier and more expensive to build.
Q. How effective will Magtrac braking be?
A. Braking and traction increase with the total number of turns in all of the half solenoids, the currents passing through the wires and the cross section area of the iron rails. In principle, Magtrac braking could be as efficient as the braking on a Formula One racing car. In reality, a far more modest braking system should meet commercial, safety and customer needs.
Drop down eddy current braking using permanent magnets and activated by a dead man's switch will also be installed as as a fail-safe backup.
2 Reducing stray magnetic fields
magnetic fields can attract ferromagnetic debris such as nuts, bolts and nails.
A number of steps can be taken to design this problem out of the system.
Figure 11. Superconducting shielding.
2.2 Bury the poles of the soft iron magnets
Figure 12. A vertical cross section at track level.
3 Keeping the runners and flux shields cold
and flux shields can be chilled using liquefied gases or dedicated
refrigerators. A combined system may be best.
4 Powering Magtrac trains
Don't get can carried away with the idea of a free ride. If the electromagnets are superconducting there are no heat losses but energy still has to be expended driving the electric currents against the back EMFs produced as the train moves.
Electrification using overhead power cables is one option, but burning hydrogen is preferred because the fuel can be used twice. First in liquid form, as a superconducting cable coolant; then as a fuel to generate electricity.
To burn the hydrogen fuel efficiently onboard, fuel cells, four stroke engines or Latent Power Turbines can be used.
Hydrogen fuel safety
5 The copper alternative to superconducting windings
The argument in favour of
superconducting windings is that they eliminate electrical resistance (Joule)
heating losses. Copper is not a
superconductor at liquid hydrogen temperatures but its resistivity is les than
5% of its value at UK average temperatures. If copper is used for the windings
there will still be some Joule heating losses at low temperatures but the
thermal energy can be used for warming the hydrogen prior to its use as a fuel.
6 "Belt and braces" braking systems
6.1 Friction brakes would still be used as a backup and to prevent stationary trains rolling down hills.
6.2 Each carriage would have wheel axles coupled to motor/generators, to provide part of the regenerative braking during normal journeys. This energy could be stored in lithium batteries.
6.3 Each carriage would also be fitted with its own Magtrac electromagnets. In the event of the principle Magtrac power supply failing, power from the batteries would be used as a backup.
6.4 Remote braking On the approaches to potential accident spots such as railway crossings, active Magtrac rails can be installed. These would include externally powered solenoids that converted attraction into repulsion. This would allow remote braking by an external operator or an intelligent CCTV system.
Figure 13. Active Magtrac rails include current carrying solenoids that can be switched on remotely. These instantly convert traction power into braking power.
Braking solenoid off: Axle casing mounted N
attracts second 1/2solenoid axle casing mounted
S. Traction power is generated.
If the track based system detects that the trains half solenoid currents have been changed to initiate braking, the track solenoid current can be switched off.
The UK mainline Health and Safety report for 2012 records four pedestrian and five car deaths on level crossings.
Protection for maintenance staff Portable half solenoid versions of the the remote braking system could be installed on lengths of track where maintainable work is being carried out while the track is still in use.
Noise reduction bonus
Dissipation of kinetic energy during braking
9 The Business Argument: Magtrac vs. HS2
9.1 Time saving for
9.2 Outline timetable for decision makers
A two stage plan:
(i) The Magtrac rails can be used for eddy current braking, as described in the first article. If we act promptly, better brakes could improve network capacity and deliver real improvements for rail travellers in five years.
The suggested timetable below relates to
the more advanced full Magtrac system.
A full Magtrac system
This timetable is flexible
9.3 More people and businesses will benefit
Figure 14. HS2 is scheduled to bring a very lopsided prosperity to a few
English cities by 2032.
Figure 15. Magtrac is a far cheaper alternative per mile that will help to stimulate the whole UK economy.
9.4 The manufacturing & export bonus
Second article, PART TWO
– A transport internet for the 2030's
Motorists will not be cajoled into giving up their cars in order to save the planet. Battery powered vehicles may be part of the solution, but battery capacity limits the distances that can be covered on a single charge. Hopefully, the range problem will be solved within a decade. If not, a Transport Internet could be the answer.
In a Transport Internet system, trains would be used for moving vehicles over long distances, with vehicle power being used for short journeys.
A three stage development plan
Magtrac and eddy current braking improved railway routes that are running under
capacity could be used for carrying vehicles.
STAGE THREE If the overhead demonstration line takes sufficient road traffic off the motorway, lanes could be removed from existing motorways and converted to Magtrac. The new rail routes would be used by freight and foot passenger trains, further reducing the pressure on motorways.
If required, Stages Two and Three could add 2,000 miles of extra track to the UK rail network without building on large tracts of extra land.
Benefits of a Transport Internet
(i) Motorists would be freed up during the train journey to do remote office work, relax or entertain the kids. Meanwhile, car batteries would be recharged to increase road travel range.
(ii) A trainload of say 30 vehicles would offer less air resistance and consume far less fuel than the 30 vehicles travelling at the same speed individually.
(iii) The existing internet has brought down the cost of telecommunications by using routing software to make the best use of international communications networks
The same thinking can be applied to transport systems.
The following example suggests how a battery powered car could use the Transport Internet to travel from Crieff in Scotland to Swansea in Wales
Figure 16. A motorist using the Transport Internet to travel from say Crieff in Scotland to Swansea in Wales might have the choice of two embarkation stations, Perth or Dunblane and several routes through England. The routing software would suggest fastest and lowest cost options. The computer analysis would be utilitarian; offering the fastest/cheapest services to the greatest number of travellers.
Freight Containers would make transitions between trains on battery powered
Reduced freight costs will bring down the retail cost of food and consumer goods.
A1 - Low cost production of hydrogen fuel
Hydrogen can be manufactured
by using electricity to split water into oxygen and hydrogen. We envisage Latent
Power Turbines being used to generate the required electricity.
These turbines have the capacity to extract heat from mild atmospheric air at 10oC
or warmer and convert it into electricity. No toxic chemicals or high gas
pressures are involved.
Here is a sketch of the demonstration LP Turbine that we planning to build at Capenhurst during the coming months. The diagram explains how heat is extracted from the atmosphere and converted into electricity.
This is a sketch of the demonstration Latent Power Turbine that we will build during the
next few months.
The Technology Strategy Board has invested £93,400 British taxpayer funding to help build the prototype LP Turbine.
A2 - Low cost liquefaction of hydrogen fuel
The boiling point of hydrogen at atmospheric pressure is -252.9 °C . Using current refrigeration techniques, cooling hydrogen to this temperature requires a significant input of electricity. However, by using LP Turbines for the liquefaction process, the heat extracted during cooling can be converted into electricity, to generate additional hydrogen.
Our power generating liquefaction process is explained in Section 5 on the LP Turbine theory page. You will need to read down as far as 5.4 before a reference to hydrogen liquefaction is made.
A3 - Reducing the cost of iron rail manufacturing
Converting iron ore into commercial grade iron or steel is a very energy intensive process. Most of this energy ends up as low grade heat that is dumped into the environment.
Latent Power Turbines can be used to cut iron making costs by capturing this thermal energy and converting it into electricity. Our process is inspired by pioneering work done by British researchers in the nineteen eighties1.
Hopefully, this time round, British inventiveness will not be wasted.
Please contact us for details of the new process.
1Pickering et al, New process for dry granulation and heat recovery from molten blast furnace slag, Ironmaking and Steelmaking 1985; 12;14-21. Compendex.
A4 - Hovercraft/airfoil tilting for high speed bends
To gain hovercraft type lift, downdrafts of air would need to be generated
beneath the carriages and skirts added to ensure that the air only escaped
horizontally when it was close to the ground.
The cushions would be partitioned longitudinally, so that two adjacent cushions run the length of each carriage. On bends all of the incoming air would be diverted into the cushion on the outside of the bend. This would reduce the tendency of trains to roll over when taking a bend at speed.
For single carriage trains, the simplest hovercraft system would require the existing streamlined nose to be replaced by a wedge shaped cavity tapering inside the body of the train. The upper surface of the wedge would slope downwards and the lower surface would be horizontal.
Roof mounted airfoils:
Each roof mounted airfoil would be split into two hydraulically adjusted wings.
On bends the wing on the inside of the bend would be tilted to produce a net
down force, with the wing on the outside of the bend being tilted to produce a
net up force.
4.3 Combined airfoil and hovercraft action: If the airfoils are close to the carriage roof, the air deflected under the airfoils can be harnessed by channelling the down flowing air into the fan assisted air cushions under the carriage.