More Trains.

The train is, in many respects a marvellous concept. It allows large numbers of freight and passengers to be carried efficiently between specific, predetermined destinations and has historically played a large part in the economic development of the settlements served by it. Traditional railways however, do have certain drawbacks- for example, the sheer expense of levelling the ground and installing miles and miles of track. In parts of Australia and Canada, a cheaper alternative has evolved- the road train. This is nothing more than a large, diesel powered truck towing a succession of trailers, but it does represent a cost effective means of transporting large amounts of freight. Problems can arise however, for example the drivers can become mesmerised by staring at the relentless miles of featureless road ahead of them, and of course the environmentalists complain incessantly about internal combustion engines. Also the trailers, having nothing to guide them, can be difficult to steer and control. These problems can be resolved however, with a little ingenuity.
I envision a modification, whereby the train is propelled by electric motors, and these are powered by a 'pick-up' in contact with a cable spooled out along the side of the road. Arranging a conventional, overhead cable or a 'third rail' would be an expensive proposition, but I don't think this is necessary. the weight of the cable, if allowed to trail, unfettered next to the road, would tend to keep it in place. Of course the 'pick-up' would tug on it, but only at one point along its entire length at any given time, and this is in any case an advantage. Sensors in the 'arm' to which the 'pick-up' is attached could measure the push or pull exerted by it on the cable, as the train drifts closer to or further from it. A fairly simple onboard computer could then use these measurements to regulate the train's distance from the cable, and thus keep it on course, freeing the driver, like his colleagues on the railways, from the need to steer.
There is one problem- a cable trailing along the ground must be insulated from it, if it is to provide useful power to the train. Conversely, to accomplish the same, the cable must be exposed to the 'pick-up'. This can best be accomplished if the top of the cable is open to the 'pick-up', while its underside is insulated. It is then necessary to ensure that the cable remains 'upright' along its whole length.
I am put in mind of 'Mr Wobbly Man', a character from Enid Blyton's 'Noddy' series. ( http://en.wikipedia.org/wiki/Noddy ). "He is a funny little man who cannot lie down because of his wobbler and always has to stand up". This is because he possessed a hemisphere in place of legs, and his weight was so distributed that his centre of mass was directly below what would equate to the mid-point of the corresponding sphere. While this can have done little for his mobility, the result is that however far he may be tilted he would always roll back to an upright position. Similarly, by weighting it along its base, our cable can be persuaded to automatically assume the correct orientation, keeping it quite literally on an even keel.
Since 'pick-ups' could be placed along the whole length, and each carriage be independently steerable in accordance with them, controlling the carriages is no longer such a problem. This system is not limited to roads either- it could be run across whatever terrain its suspension and tires could cope with. Thus it could become a cost-effective part of the transport infrastructure in any environment where a cable could be laid. Places such as the Sahara, northern Canada, central Australia, perhaps even Antarctica, or, one day, the moon.
In practice a second cable would be required to complete the circuit of course, and I couldn't say whether AC or DC supplies would be more appropriate.