Tracklaying With Third-rail

Using third-rail electrification in Rail3D is very easy. The most common types are already available as track models, and if you need something special it’s usually just a matter of adjusting the dimensions and positions of the rails. Laying third-rail track needs a little bit of care in keeping the third-rail on the correct side, and pointwork can be a little trickier than with standard track.

Types of third rail

Top-contact

Top-contact third rails are relatively rare outside the uk, and found mostly on older lines (e.g. various narrow-gauge lines in the French alps and the “petit train jaune” in the Pyrennees).

For British prototype practice, a very good resource is Russ Elliott’s 3rd and 4th rail dimensions and settings page. Obviously, you will have to convert all his dimensions back from 4mm scale to use them in Rail3D.

the four-rail system of London Underground is also based on top-contact.

Bottom-contact

Most third-rail systems outside the uk use the bottom-contact system, where the third rail is supported on C-shaped brackets so that its lower surface is free. The big advantage of this system is that it allows the use of an insulating cover to protect railway staff from accidental contact with the third rail.

Laying third-rail track in Rail3D

As soon as you try to do it, it’s pretty obvious how you should lay third rail. The main thing to watch out for, obviously, is that the third rail should never cross the running rails! The main tools for achieving this are the insert node and swap track side functions on the link context menu.

At turnouts you simply have to make sure that the third rail of each of the diverging tracks is on the outside. Where two turnouts are connected in a crossover, you will have to insert at least one extra node in the middle of the crossover to allow the third rail to chnge sides.

Where two tracks cross in a diamond crossing, you will need to leave a gap in the third rail, by using the corresponding non-electrified track type.

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