What is MAIT ?

Figure 1: Vertical transfer between supported and suspended type carriers with a transferrer lift occurring between the two.

The three ``ingredients'' of MAIT are:

1. cabins, containing passengers or freight
2. carriers, moving cabins along tracks and
3. tracks, capable of guiding carriers along a path.

The MAIT vehicle consists of a cabin attached to one carrier. The novel feature is that the carrier can be exchanged automatically.

Like the shipping container, the cabin is a box without wheels or motive power. The carrying capacity would be similar to a car or small van, where the internal design will be appropriate to their various functions. Cabins will have attachment points by which they can be transferred from one carrier type to another by a variety of means. But, unlike shipping containers, these attachments are designed so that automatic transfer can be performed efficiently, rapidly and safely. Cabins will generally be moved under computer control and journeys will be made by transferring them automatically from one carrier type to the next and by routing to the specified destination. At the start and end of trips, cabins would be branched into off-line stops or placed on a stand, allowing goods to be loaded or passengers to take their time alighting without affecting the movement of other vehicles.

Cabins for passenger and freight can be available for hire or be owned by the user. Passenger cabins are large enough to accommodate four seated adults with baggage and long enough to allow an adult to lie down in, and will be able to provide a private space for sleeping on long journeys. The furniture inside passenger cabins can be designed for various circumstances, for example to accommodate a person in a wheelchair, shopping trolleys or prams, and provision made to allow these to be rolled in easily. Cabins for longer journeys can be provided with access to entertainments, the Internet and telephone connections. A cabin management system will be needed to supply the right sort of cabin, to provide efficient re-use of cabins for hire and parking for privately-owned cabins. Freight cabins can be variously designed for automatic loading and unloading with industrial pallets, for carrying liquids or refrigerated for carrying foodstuffs.

A carrier is any vehicle with motive power, dedicated to carrying cabins. Carriers will generally be electrically-powered, quiet and pollution-free. In the established system a particular carrier will automatically move on a specific type of track, which can be either a suspended- or supported-type guideway, or a road with the appropriate navigation equipment. Depending on the local traffic situation, parts of the track can be either on street level, overhead or underground (for examples see Section 3). The elevated guideways are slim and similar to walkways for pedestrians because payload of MAIT vehicles is limited to $500$kg. The carriers and the tracks can be designed with any transport technology as long as it adheres to the MAIT standard specifications (see below). The carrier-track technology could cover a wide range of speeds, carrying capacities and propulsion systems, for example:

• guideway carriers with hard rubber tires, running in a suspended-type guideway or on a U-shaped supported-type guideway. Depending on the guideway design, such a carrier has medium to high carrying capacities and speeds of up to $130$km/h. Suspended-type carriers are particularly suitable for indoor transport because they do not require on-floor guideway structures.

• road carriers with wheels designed to run on ordinary roads. For navigation, induction loops are embedded in the road. Energy could be stored by a small battery or a flywheel which is recharged at each stop. This carrier type is flexible and the induction loops are cheap to implement, but it would be slow and suitable only for short distances. However, there are areas such as narrow streets in historic towns where elevated guideways will be unacceptable and ground-level operation is unavoidable.
• magnetic levitated (MAGLEV) carriers using electrical linear synchronous motors. These carriers have high carrying capacity at a high speed. They are suitable for inter-city connections with low branching.

A definitive requirement is that cabins are transferable from and to other carrier types by means of transferrers. Fig. 1 shows an example where the active part of the transferrer is a lift which engages with the cabin and moves it up to the suspended guideway or down to the supported guideway. Fig. 2 shows how a cabin might be transferred from one supported-type carrier to second supported-type carrier or stand. Such a horizontal movement of a light weight cabin requires little power, allowing the transferrer mechanism to be built into the carrier.

MAIT has a vital capacity to evolve and adapt. Each individual city is different and will present specific problems, requiring tailor-made solutions. The city planner will be able to draw on many different automated carrier technologies, each with their own strengths and weaknesses, and combine them using each to the best advantage to provide a seamless transport system. Most types of guideway could be installed or removed with far less upheaval and damage to the fabric of the city than that caused by roads. Overhead carrier guideway and supports would be made in prefabricated sections mounted on minimal foundations. MAIT will be quiet and non-polluting and, with a limited maximum loading and small loading gauge, can be comparatively easily routed over, under and through existing city structures. The essential features of the above described system are:

• driverless, on-demand and 24h origin-to-destination transit in individual cabins without intermediate re-embarkation--the entire cabin is transferred.

• the carrier-track technology can be adapted to operate cost-effectively in all transport environments. Therefore, using different carrier types, the MAIT network could reach city centres, low traffic density residential areas, or even manufacturing machine inside factories.

• carriers and tracks could be used to transport passenger cabins during daytime and freight cabins during the night. This means that the parts of the system with high capital investment can be in use for a greater proportion of the time. Spreading the load more uniformly throughout the day means that the system cost can be lower for a given total capacity.

• the heart of MAIT is a specification of open standards defining: envelope volume of cabin; electro-mechanical interface between cabin, carrier and transferrer; communication protocols which are used to coordinate cabins, carriers and tracks; safety, security and comfort criteria.

• new carrier designs can be added to the system provided only that they adhere to the above-mentioned standard specification.

• the components and operators of the system can be owned by individuals, private companies or public authorities.

Figure 2: Picture Sequence, showing a parallel transfer of three cabins from a road carrier to a suported-type guideway carrier. (a) The three cabins in the front are ready for transfer and are aligned with the three empty guideway carriers. (b) the transfer is in process. (c) transfer is terminated. Now the three cabins can continue their trip on the guideway--also on the elevated one as shown in the background.

(a)	(b)	(c)