NXSYS, Signalling and Interlocking Simulator

From nycsubway.org



Please note! Downloads and documentation of NXSYS, now much improved, are now available on the developer's web site. Available for Windows 10 and MacOS. Click here.

NXSYS, New York City Subway Signalling and Interlocking Simulator, A tool and toy and labor of love by Bernard S. Greenberg.

NXSYS is an application that recreates for you the experience of controlling switches, signals, and trains in the New York City Subway system. Rather than conventional menus and toolbars, NXSYS presents to you the exact same user interface as so-called "Entrance-Exit" "pushbutton interlockings" present to New York City subway towerpersons, except that instead of pressing buttons with your finger, you click with the mouse. And instead of commanding real trains full of people, NXSYS simulates them cybernetically. You see the same display, get the same options and responses, must learn the same skills, and may enjoy the same pleasures as a towerperson at an "entrance-exit" interlocking.

There is no more comprehensive, detailed information source on New York Subway Signalling publicly available, or perhaps even to insiders. This is THE way to learn about New York City Subway signalling. And it's for free, fun, interactive, extensible, and assumes no prior knowledge. (If you wish to learn about NY City signalling right now on the web, and aren't interested in trying NXSYS, please visit Subway Signals: A Complete Guide, written by the author of this program and its documentation.)

The trains and tracks are imaginary, but the control panel, the extensive relay logic circuitry, and the real-time behavior and interaction of you and the imaginary trains and tracks are not. You press buttons and establish and cancel routings, control signals and switches, and interact with moving trains. You are limited by the circuitry to safe moves -- you are prevented from sending trains crashing at each other, setting routes that conflict with each other, moving switches while trains are on them, or executing any other invalid or dangerous action. Learning to control the switches and signals under these constraints is by no means trivial, and this is wherein the fun of NXSYS lies. NXSYS is supplied with two sample interlockings, a (fairly complex) 4-track layout, and a full-spec detailed three-track layout, an automatic demo that shows you what to do and comments on it, and a comprehensive help file that explains not only all the functions of the program and supplied interlockings, but all of the railroad signalling, switching, and New York-specific concepts involved.

NXSYS actually simulates relay wiring and logic designed according to New York City Transit Authority models and standards that have changed little in forty years. For the electrically-inclined, NXSYS allows the actual relay circuits to be shown in standard NYCTA notation, printed out en masse to a system printer, and actually observed in operation! Information is available for designing your own layouts. Not insignificantly, NXSYS can also be used as a powerful tool for interactive relay-logic design and simulation.

NXSYS can be viewed, utilized, or enjoyed at any of four levels:

  • An entertaining rapid-transit video game for those who love the subways and wish to recreate the experience of navigating the tracks, and learn more about the subways and their signals.
  • A comprehensive, interactive learning tool for the operation of rapid transit signalling and NX/UR control towers sufficiently detailed and accurate to be of value to those actually responsible for operating such equipment.
  • A detailed guide to the sample implementation of such systems in electrical relay logic, observable in action down to the relay level.
  • An interactive computer-aided design (CAD) tool for designing and debugging your own interlockings and signal circuitry.

Downloads and Documentation

Please note! Downloads and documentation of NXSYS, now much improved, are now available on the developer's web site. Available for Windows 10 and MacOS. Click here.

New!!! Introduction to NXSYS Video

Introduction to NXSYS Video. Watch on YouTube.

New!!! NXSYS (v2) sources for MacOS on Github

NXSYS (v2) sources for MacOS on Github

Legal Disclaimer

Microsoft, Windows, Windows 95, Windows 98 Windows NT, Windows 2000, Win32, Win32s, and Visual Basic, are a trademarks of the Microsoft Corporation. Apple, Macintosh, Mac, and OS X are trademarks of Apple, Inc., registered in the US and other countries. Pentium and Intel are trademarks of the Intel Corporation.

"NX" refers to a scheme of railroad switch and signal control offered by General Railway Signal, Inc. (a unit of SASIB Railway Group). Neither this software nor its documentation has been authorized, approved, or verified by them or any other railroad signal concern or the New York City Transit Authority or its successors.

If you want to use these ideas and software tools for your own model railroad, have fun, but please be aware that the design of safe, reliable signal circuitry for real railroads and other life-critical missions is a highly-skilled specialty requiring years of training, apprenticeship, and certification. Any principles gathered from the documentation and circuitry of this program, even though they often reflect standard practice, are not to be construed as a substitute for circuit design by certified persons and organizations under legal contract. In specific, the author disavows any responsibility for any harm, damage, or injury resulting from use of these circuits or schemes for any purpose whatsoever. These circuits and documentation are provided for educational, demonstrative, and entertainment purposes only, and are not to be used for control of life-critical missions. What is more, if you nonetheless attempt to use these circuits or schemes to construct and offer for sale any device or system, you alone are responsible for ensuring that no patents, copyrights, or other applicable rights are being violated thereby. Download of this software constitutes acceptance of these terms.

This software is offered without charge, "as is", by the author, Bernard S. Greenberg. It is thought to be relatively bug-free, although bug reports will be fielded using this form, but no response in any given time promised. No representations, warranties, guarantees, or claims about operability or suitability for any purpose are made. This software is intended for educational, demonstrative, and entertainment purposes only, and is not suitable for use for control of actual railroads or other life-critical missions. The author assumes no responsibility for any damage, harm, injury or loss resulting from use or misuse of either the software or the relay circuit designs therein. The author assumes no responsibility for errors resulting from corruption of the distribution media or files or inadvertent or deliberate corruption in transmission. You may use and share this program as you wish, but are not permitted to incorporate this program or its parts in any distribution, collection, or commercial product without the consent of the author. If you redistribute it, you must redistribute the zipfiles as you received them, intact, with all their components as posted. Download of this data constitutes acceptance of these terms.

This software is intended for personal use and personal education, and offered free of charge under those conditions. Business concerns and governmental organizations, rapid transit and engineering in particular, seeking to use this software for other than entertainment or personal education should contact the author about licensing arrangements and possible future development.

NXSYS software, documentation, and interlockings Copyright ©1994-2001, 2014, 2021 Bernard S. Greenberg.

Page Credits

Descriptions and graphics on this page (unless otherwise noted) are Copyright © 1997-2002 Bernard S. Greenberg (contact).

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