Previous | Contents | Index | Next

# B.2 XTrackCAD Terms

Active Endpoint - when placing a turnout, the endpoint which is used as a 'handle' when moved along other tracks.

Auto-connect - when placing turnouts (Section 2.7) and creating parallel (Section 2.1.5) tracks, the new track will automatically be connected to other tracks if the tracks are aligned properly.

Block Gap - provides control by dividing the layout into electrically isolated blocks, where trains can be slowed or stopped by lowering or cutting the power to a block. Dividing a layout into blocks also permits operators to run more than one train on a layout with much less risk of a fast train catching up with and hitting a slow train. Blocks can also trigger signals or other animated accessories on the layout, adding more realism (or whimsy) to the layout. Three-rail systems will often insulate one of the common rails on a section of track, and use a passing train to complete the circuit and activate an accessory.

Cornu - * Cornu curves are a family of mathematically defined curves that define spirals that Euler spirals and elastica come from. They have the useful property for us that curvature increases linearly along the curve which means the acceleration towards the center of the curve also increases evenly. Railways have long understood that smoothly changing the radius is key to passenger comfort and reduced derailments. The railway versions of these curves were variously called easements, Talbot or Euler spirals.

DXF Format - Abbreviation of Data Exchange File, a two-dimensional graphics file format supported by virtually all PC-based CAD products. It was created by AutoDesk for the AutoCAD system.

Easement - special sections of gradually curving track used to connect straight and curved tracks (or two curved tracks). Easements reduce the effects of sudden changes in track curves which can cause derailments. They also look great!

Endpoint - One of the most important concepts in XTrackCAD is the endpoint. A piece of flex-track has an endpoint at each end. An endpoint has a position and an angle and it can be connected to other endpoints. The endpoints control where the track is placed and how it is connected.

- Turnouts have several endpoints (normally 3).

- Turntables have a varying number.

Error Message - an error message displayed in the Status Bar (Section 3.1) accompanied by a beep.

Flex-track - Prefabricated flexible sections of track used on a layout. It usually comes in straight, three-foot-long sections which can be bent or shaped as needed. This term is also used for hand-laid track.

Frog - the place on a turnout track where one rail crosses the other.

Gauge - The distance between the inside of the heads of track rails. Most real railroads in North America and Europe are built to a standard gauge of 4'-8 1/2". Narrow gauge means rails with a width less than standard gauge. For example, On3 means O scale trains with three scale feet between the rails.

Handlaid - Track that's built with handmade ties, rail, and spikes.

Helix - A rising curve which turns around an axis like a corkscrew. Used on multilevel layouts to allow trains to go from one level to another.

Info Message - an informational message displayed in the Status Bar (Section 3.1).

Object - an item on the layout, such as a track segment, table edge, line, note or text.

Points - the part of the Turnout that moves to select a path.

Reverse Curve - a piece of track which curves in one direction then changes direction without any appreciable length of straight track between the two curves.

S-Curve - a curve which bends in one direction and then the other, forming an S-like shape.

Sectional Track - prefabricated track which cannot be bent, split or changed.

Selected Endpoint - when selecting track for various reasons the selected endpoint is the one closest to the selection point.

Tangent - A line, curve, or surface meeting another line, curve, or surface at a common point.

Track Segment - any piece of flex-track, turnout or sectional track.

Turnout - A piece of track that allows a train to go from one track to another. Called a switch on a real railroad. Referred to by number. For example, a no. 6 turnout spreads one unit for each six units of travel measured from the frog (the point at which two rails join to form a V).

- In XTrackCAD, Turnouts also include sectional Tracks, crossings and forms of prefabricated (non-flex) track.

Turnout Frog - the place on the turnout track where one rail crosses the other.

Turnout Number - the ratio of the number of units along the center line of a switch frog traversed for each unit the frog spreads to the sides. A No. 4 frog diverges 1 unit for every 4 it moves ahead; a No. 6, 1 for every 6 units. Although we usually refer to a turnout or switch number, in reality the measurement is for the frog.

Turnout Points - the part of the Turnout that moves to select a path.

Unconnected Endpoint - an endpoint which is not connected to another.