Planar rail (ConceptTopic, 3)

From Hi.gher. Space

The planar rail is Keiji's idea for 4D road transport.

The basic concept is for the base of 4D vehicles to be confined to a 2D surface (or in practice, a pair of parallel surfaces, like how 3D railways have two rails, one for each lateral side of the train). By doing this, many analogies to 3D road vehicles can be drawn, and it becomes more efficient to drive than in the traditional analog of a 3D surface with "spaceship steering".

One may recognise Keiji's terms of frontal, vertical and lateral and that in 4D, the usual scenario for an animal is one frontal, one vertical and two lateral dimensions. In traditional 4D land transport, this is still the case, and the existence of two lateral dimensions (as opposed to just one in 3D) causes various effects to occur which make driving more difficult, for example, there is no "left or right", but a whole circle of 360 degrees in which to turn, and the orientation of a forward-pointing vehicle becomes important.

In the planar rail system, the two lateral dimensions are subdivided into one confined lateral and one navigable lateral. In 3D, in road transport the only lateral is navigable, while in rail transport the only lateral is confined. So planar rail combines both. Vehicle doors are located on the left and right of the confined lateral dimension - where they would be on trains - while steering operates in the left and right of the navigable lateral dimension. This already improves road safety as it becomes impossible to enter or leave a vehicle in a direction that is part of the road where other vehicles are driving.

Driving in planar rail is very similar to driving on a motorway in 3D. On main roads, you steer left and right only to select your lane - lanes fill the navigable lateral. All changes in direction are done on the confined lateral, meaning the vehicle is pulled into the correct direction while the steering wheel simply says straight on, like how a 3D train never leaves its tracks (under normal circumstances, anyway). This includes at junctions: one leaves the road they are on, takes a sliproad which bends in the confined lateral into the correct orientation, and then joins the new road they were heading for. Junctions do not require any bridges or tunnels, as the different roads simply pass by each other within the 3D surface of the land.