An Interface Standard for a General Transport System

by Bengt Gustafsson


Beamways AB has taken as one of its task to participate in standardisation efforts in the area of GTS (General transport systems). GTS can be seen as “PRT large scale”, i.e. PRT applied to a large geographical area. GTS was coined by the
Swedish Institute for Transport and Telecommunications Analysis (SIKA). (see the Bubbles and Beams II animation for

an illustration of the concept).


GTS places some new demands on the implementation. While a larger geographical area in general demands higher travel speeds and larger capacity, we feel that the main obstacle to its introduction may well be compatibility issues. With small PRT networks it is feasible to be confined within one manufacturer’s system. When multiple such systems reach each other it is essential that the cabins of one system can ride on the other system and vice versa. Thus some kind of standard is required.


One possibility is of course to appoint one of the leading manufacturer’s system as the standard system. This is impossible to do until quite a few networks have been installed and proven themselves. At this point a fierce battle between manufacturers will of course arise as the advantage of being appointed the standard system is very great.


Another possibility is to create a new standard from scratch, based on the experience of the first systems. This standard would not be compatible with any pre-existing system and thus leave the early customers with non-standard systems not being able to interoperate with contemporary systems.


To solve this future problem one suggestion is to make the cabin separable from the drive truck, and standardize the interface This standard can be developed at any time, is relatively simple, is mostly neutral between manufacturers and offers great advantages to PRT system buyers. The drawback is of course that the vehicles will be somewhat more complex, due to the added mechanical couplings. But not all vehicles need to be separable into cabins and trucks for a system to be standard compliant. The only requirement is that standard cabins can travel on the system, possibly on specially designed drive trucks. Similar ideas have previously been put forth by Modular Automated Individual Transport (MAIT) concept.


The main advantage of this type of standard is that interoperability between a system and any future adjacent system can be guaranteed. It is also possible to extend a PRT system with newer generation infrastructure without having to replace any of the previously installed equipment. The standard also makes it possible to design the infrastructure for a specific task, such as high speed, tunnel, tight corners etc. Cabins can then be transferred between the different systems without passenger intervention. It is also possible to transport cabins on regular systems such as trains and ferries.


The standard will specify mechanical cabin holders, power and communication connectors and computer network protocols. The standard will also impose limitations on the size and weight of the cabins, so that the transportation infrastructure can be designed to fit and carry the cabins.


By specifying dual sets of cabin holders, top and bottom, the standard will cater for both supported and suspended system designs as well as provide a convenient way of transferring cabins between any pair of infrastructure systems.


It is envisioned that the standard would contain at least two profiles of different size. One classical PRT size and one larger size which would offer additional weight and size capacity, for instance allowing transport of regular cars using a palette system and substantial cargo traffic. One suggestion is to make this larger profile compatible with today’s goods containers. The container standard allows for weights up to 40 tons though, which could be a too high level to be feasible.


The standardization process can run in multiple stages, with different standard versions as output. The first version will just contain enough information to enable manufacturers to brand their systems as standard compliant. This means that things like the maximum size, weight and power consumption must be agreed upon. The next version will contain a complete standard for the PRT profile, defining the couplings, connectors and network protocols. The larger size standard can mostly be left for the future.

Last modified: December 18, 2007