Three-rail toy train track provides a distinct advantage for the toy train operator wanting to use the position of trains to operate trackside accessories or to control train action: the track itself can be used for a low-cost, practically invisible, mechanism for detecting a train's location.

Activating an accessory with an isolated outside-rail has been around for a long time. (See History .) Thus, all three-rail track systems provide a mechanism for providing an isolated outside-rail.

All track systems include some sort of special track section with one outside-rail isolated. These can be useful, but full use of isolated outside-rail track blocks for accessory and train control will require long track blocks of any track component. The track system needs to have:

• Naturally insulated, or a means to insulate, one outside rail from the other.
• A mechanism for isolating an outside rail segment from an adjacent rail segment.
• Easy connection of wires to rails, preferably without the need for special track sections or visible connecting devices.

Controlling trains with isolated outside-rail blocks will also require the center rail to be isolated into track blocks.

Scroll down or use the click index to review summaries of isolated outside-rail approaches with various three-rail track systems. Click a bar for more detailed information.

Tubular track sections with an isolated outside rail are commercially available, but only the conventional length straight sections. Lionel's current part numbers are 6-12840 for an O-Gauge and 6-12841 for an O27-Gauge track section with an outside-rail insulated from metal ties and a plastic rail pin for isolating the rail from adjacent track sections. Other vendors of tubular rail track also offer isolated outside-rail track sections.

Any tubular track section, straight, long straight, or curves, can have an outside rail isolated; click the bar for a complete description of how to isolate rails from metal ties and construct isolated outside-rail track blocks.

Lionel's FastTrack sectional system has formed sheet metal rails attached to a gray plastic roadway with simulated wood ties. The plastic base naturally insulates rails, including outside rails. Conventional track sections have a metal strip jumper that interconnects the outside rails.

An isolated outside-rail track block can be constructed with Lionel FastTrack by using the 6-12029 "Accessory Activator Pack" or by modifying conventional track sections. Related Lionel track products include: 6-12027 "Accessory Activator Extender," 6-12016 "Terminal Section," and 6-12053 "Accessory Power Wire."

Click the bar for details on isolated outside-rail and isolated center-rails using Lionel FastTrack.

SuperStreets is an O-Gauge three-rail, sectional track system with the appearance of a city street. A gray plastic base has formed sheet metal outside rails and a thin sheet metal center power strip. The plastic base naturally insulates rails, including outside rails.

Outside rails have a metal "bridge" piece held with the rail tabs and soldered in place. The center power strip is also fastened with bent-over tabs. A metal piece is also attached to the center power strip. The bridge pieces also serve for power wire connections.

An isolated outside-rail track block can be constructed by modifying conventional track sections.

Click the bar for details on isolated outside-rail and isolated center-rails using the Lionel/K-Line SuperStreets track system.

The Atlas O 3-Rail 21st Century Track System has solid rails attached to a frame of plastic ties. Track is available with nickel silver or solid steel rails. The plastic ties naturally insulate rails, including outside rails. Outside rails are not bridged together.

Track sections are assembled using rail joiners in each rail. #6093 "Insulated Rail Joiners" are used to construct isolated rail track blocks.

Click the bar for details on isolated outside-rail and isolated center-rails using the Atlas O 3-Rail 21st Century Track System.

The MTH RailKing RealTrax track system has solid rails attached to a plastic base with simulated wood ties. The plastic base naturally insulates rails, including outside rails. Outside rails are not bridged together.

The 40-1029 "10" Insulated Straight Section" provides the mechanism for constructing isolated outside-rail and center-rail track blocks.

Click the bar for details on isolated outside-rail and isolated center-rails using MTH RailKing RealTrax.

Now you are ready to use isolated outside-rail track blocks to operate trackside accessories. Click the bar to see how.