A transport internet to reduce traffic pollution

Article summary: The internet has brought down the cost of telecommunications by using routing software to make the best use of international communications networks.

We propose applying the same thinking to transport systems. Battery powered vehicles would have their range extended by being carried on trains for long journeys. Routing software would identify optimum routes to speed up journeys and make the maximum use of the railway network.
We suggest a novel traction and braking system for trains that would pack more trains onto the tracks by improving acceleration and reducing braking distances.

As a spin-off, the train traction system proposed for the Transport Internet could be used to increase the passenger carrying capacity of current rail networks, without the environmental damage and high costs associated with building new routes such as Britain's proposed High Speed Rail Link.

The problem to be solved:

"Greens" and motorists have different priorities

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.

Our solution is a hybrid system with battery powered vehicles being carried by trains to increase their range.

The internet analogy
The internet brought down the cost of telecommunications because it used computer systems to route information around the transmission system more effectively.
In a similar manner, vehicles, freight and passengers travelling on long complex routes could be moved on and off rolling stock at any of the stations along a route, to make maximum use of the network. Optimum routes would be chosen, to avoid road diversions, long uphill gradients and other battery draining hazards.

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 1. 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.

A demonstration route could be built between two major cities about 100 miles (160 km) apart, e.g., in the United Kingdom; between Birmingham and Manchester.
“Intelligent” front wheel trolleys would manoeuvre vehicles on and off the trains.
Second generation electric vehicles would have built-in automatic manoeuvring systems, to eliminate the need for trolleys.

Motorists would be freed up during the train journey to do remote office work, relax or entertain the kids. Meanwhile, batteries would be recharged to increase road travel range.
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.

Expanding the system
If the system proves popular with motorists, extensions could be built on exiting motorway lanes because motorway usage will drop as rail transportation of vehicles increases. The new routes could also be used by freight and foot passenger trains, further reducing the pressure on motorways. Converting motorway lanes to railway tracks would involve imaginative engineering, but the MagTrac system proposed below would ease the technical problems, because it would allow trains to travel on steeper gradients than existing traction units. It would allow, for example, trains to travel  on flyovers, in the vicinity of motorway exits.

The Chilterns Bonus
The Transport Internet could provide a template for modernising the British railways network, without building an expensive new track that slashes through the Chilterns.

The key problem to be overcome
Trains require far greater braking distances than motor vehicles because of the poor grip of steel wheels on steel tracks. In order to allow trains to travel closer together and hence increase track capacity, we need to replace steel-on-steel contact as the primary braking mechanism.

MagTrac: Contact free braking and traction

Vehicles running on the transport internet would require efficient braking systems to operate safely. A combined electromagnetic braking and traction system is one possibility.
Magnetic levitation (MagLev) systems, with rolling stock floating on magnetic cushions, have been touted as the future of railways, but MagLev systems are very expensive to set up.
We propose a simplified form of maglev system with trains running on conventional wheels combined with an electromagnet system that offers efficient traction and braking.
We will refer to the simplified design as a magnetic traction or MagTrac system.

The basic concept behind MagTrac
This can be understood by considering what happens when an electric current is passed through two solenoids resting on a soft iron bar.

Figure 2. In addition to attraction or repulsion between the two solenoids, each solenoid experiences a repulsive force between itself and the enclosed soft iron bar.

Figure 3. To move a lightweight platform along a short length of track, the soft iron bar needs to be bent into a U shape.

A practical traction unit

In order to produce a net upward force and allow the platform to move along a track of indefinite length, the solenoids need to be opened up to form "half-solenoids."

Figure 4. This is a “half solenoid”. When an electric current is passed through the wires it produces a magnetic field similar to a full solenoid, but its asymmetry results in a net upward force when it rests on a soft iron bar.

Figure 5. An alternative, series winding. The neutralising effect of the upper half solenoid is minimal, because of its greater distance from the soft iron rail.

Preferably, the conducting wires are made from superconducting material and the half solenoids are immersed in very cold chambers protected by Dewar insulation. (Details elaborated later.)

Figure 6. The magtrac system can be extended indefinitely.
The activated half solenoids will be referred to as runners and the lengths of soft iron tracks as stators.

Figure 7. On fairly straight sections of line, the stators can be laid inside conventional rail tracks, allowing the existing infrastructure and sleepers to be used.

Figure 8. Each unit of rolling stock is fitted with four sets of runners The inner runners are used when travelling along straight sections of track, the outer runners on sharp bends.

Figure 9. Trains have a tendency to roll over when taking a sharp bend at speed. The MagTrac solution to this problem involves no mechanical moving parts and is simpler than a complex tilting train mechanism.
If MagTrac trains run on "reclaimed" motorway lanes, where there is good bridge clearance, this additional stability would allow double-decker trains to be used. foot passengers would travel on the upper deck.

Speed and the energy penalty

Wind resistance increases dramatically with travel speed for all forms of land transport. So, an energy penalty has to be paid for getting to the destination sooner.
MagTrac offers a subtle advantage here: As the on-board electromagnets work harder to overcome increased wind resistance, the repulsive forces between the magnets and the iron rails also increases. This eases the load on the track wheels and reduces their rolling resistance.

Reducing maintenance costs

Aging of the tracks is reduced because skidding during acceleration and braking is eliminated and vibrations at speed drop with the reduced loading on the track wheels.

Reducing stray magnetic fields

Stray 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.
For example, the runners are lodged in cold chambers where they become superconducting. Magnetic flux cannot penetrate a sheet of superconducting material, so by lining the out facing walls of the cold chambers with superconducting material, magnetic flux shields can be created.

Figure 10. Design features to reduce stray magnetic fields.

Additional measures to prevent damage by small items of debris include mounting miniature "cattle fenders" and scavenging electromagnets ahead of each item of rolling stock.

Keeping the runners and flux shields cold
Runners and flux shields can be chilled using liquefied gases or dedicated refrigerators. We propose a combined system.
New designs of cryocoolers (low temperature refrigerators) created for use with rolling stock are published on our superconductors and cryocoolers web page.

Powering MagTrac trains

Electrification adds to the cost of building a new railway line and may not be practical because of the additional current loading required to recharge vehicle batteries on-route. Liquefied hydrogen is a more cost effective fuel, with our proposed cryocoolers being used to keep the stored hydrogen cold. The heat absorbed as the hydrogen evaporates and warms, prior to burning in the engine would constitute the primary MagTrac superconductor cooling system. Cryocoolers would be used to provide top-up cooling for the superconductors.

Liquid hydrogen, carbon footprint considerations. The Magtrac proposal is inherently more efficient than using liquid hydrogen to power road vehicles. This is because Magtrac uses the liquid hydrogen twice, first to chill the solenoids to superconducting temperatures, then as the fuel for the train's battery charging and traction systems.

Making stage by stage progress
A Transport Internet would require the integration of several engineering innovations. Before laying brand new tracks along motorway routes, the MagTrac design should be tested by using it to upgrade an existing railway line.

If this was done promptly and in the South of England, it would give politicians and planners practical experience of a cheaper, greener alternative to the proposed environmentally damaging High Speed Rail Link.

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