JMRI: Set Signals at Level Crossing Help
Author: Dave Duchamp
Keywords: JMRI help Layout Editor panel

# Set Signals at Level Crossing

## Introduction

A level crossing is a special piece of track that models two tracks crossing at grade. A level crossing is commonly referred to as a diamond. A level crossing has four connection points, named A, B, C, and D, and two tracks, designated 1, for the track connecting points A and C, and 2 for the track connecting points B and D. When a level crossing is created, track 1 (AC) is the horizontal track, and track 2 is the inclined track. The naming convention is shown in the diagram below.

This tool will only place turnouts if track 1 (AC) is horizontal or vertical (or mostly horizontal or mostly vertical). Because the signal icons have only limited rotation capability, the signal icons look best if the two tracks of the level crossing are almost perpendicular to each other.

Either one or both tracks may be signaled. For the Simple Signal Logic generated by this tool to work correctly, the level crossing should serve as a block boundary for each signaled track. For example, if track 1 (AC) is signaled, the track segment connected at A should be assigned to a different block from that at C. The AC track within the level crossing may be assigned to either block. Also, the crossing track should be assigned to one or more blocks with occupancy detection, so Simple Signal Logic can be set up to protect against a crossing train.

For each signal head, check boxes are available for selecting whether an icon is to be placed on the panel, and whether control logic is to be created for the signal head. Regardless of whether icons are placed or logic is created, Layout Editor will record that the entered signal heads are assigned to the specified level crossing. Assigning signal heads to level crossings is important to completely describe your layout in Layout Editor. Even if you elect to place your icons and set up your signal logic manually, you should use this tool to assign the signal heads to their level crossing.

## The Set Signals at Level Crossing Dialog

When this tool is selected, a dialog is shown for entry of information that will uniquely identify the level crossing, and for entry of the names (system or user) of two or four signal heads to be assigned to the level crossing. If entry to the tool was via the level crossing's popup menu, the level crossing is identified from the popup menu, and block information is automatically entered. If entry to the tool was via the Tools menu, one or two block names that uniquely identify the level crossing should be entered. This could be the two blocks assigned to track 1 and track 2. Or it could be just one of these blocks, provided no other level crossing uses the same block or block combination. It could also be the blocks assigned to track segments connected to the level crossing--any combination that allows the tool to uniquely identify the level crossing will probably work. If the tool cannot identify the level crossing an error message results.

If signal heads at this level crossing have been assigned previously, click Get Saved to retrieve the names of signal heads currently assigned to the level crossing.

Signal heads must be entered in pairs. If head A is entered, then head C must also be entered. Similarly, if head B is entered, then head D must be entered. Note that if two entries are blank, the tool assumes that there are no signal heads for that track, and any previous assignment of signals to that track will be automatically deleted, along with signal icons on the panel at those positions if there are any. Similarly if there was a signal head previously assigned to any position, and you enter a different signal head in the same place, the new signal head will replace the previous signal head, and the icon of the previous signal head (if there was one) will be deleted from the panel. If a signal head is changed, you must redo any logic that involves it.

For each signal head, check boxes are available for selecting whether an icon is to be placed on the panel, and whether Simple Signal Logic is to be created for the signal head. Regardless of whether icons are placed or logic is created, Layout Editor will record that the entered signal heads are assigned to the specified level crossing.

Check Add Signal Icon to Panel to request that an icon for a signal head be placed on the panel at the level crossing position indicated. This tool can only place a signal icon on a level crossing where track 1 (AC) is almost vertical or almost horizontal. If this is not so, a message is printed, and you should place the signal icon manually using the Layout Editor tool bar. Regardless, the signal head name is assigned to the specified level crossing position.

Check Set up Logic to request that the tool set up a Simple Signal Logic for a signal head. The tool will create the logic and automatically fill in entries from the information available. If the tool does not have enough information available to set up the logic, a message results, and you will have to return later after more signals and/or blocks have been assigned on the panel. If the tool does not have enough information to protect against a crossing train, a warning message results, but the logic is still created.

## Notes

When setting up logic, this tool will follow track within a block until it finds a signal at the end of the block away from the level crossing being signaled. If your layout contains sections that are signaled and sections that are not, to get this tool to set up logic correctly, you may have to place a virtual signal (a signal that does not correspond to an actual signal on the layout) at the unsignaled end of the block that connects a section of track that is signaled with track that is not signaled. If a block ends with an end bumper, no signal is required at the end bumper.

If a block has an internal turnout (the turnout, and the track segments at its throat and continuing legs are within the block), the program will expect signals at that turnout even if it's not at the end of the block. However, at times the user may not want to signal a seldom used turnout within a block. When following track through a block, the program will skip over unsignaled internal turnouts if Skip Unsignaled Internal Turnouts is checked in the Layout Editor Tools menu. It will always, however, warn that it is doing so. Use this option with caution. There is no signal protecting against a skipped turnout being set incorrectly, so if an unsignaled internal turnout is not set correctly, derailed trains could result.

This tool sets up three-aspect signaling. If you have a special situation at a signal, you may have to edit the information entered by this tool into the Simple Signal Logic. If you would like four-aspect signaling, you can easily manually edit the logic to achieve this. Similarly, by simple hand edits of the logic, you can add approach lighting. The Simple Signal Logic dialog can be accessed from the popup menu of each signal icon. If your special situation cannot be handled by Simple Signal Logic, you should refer to Logix to tailor the signal logic to your needs.

Please remember to save your Panel after using this tool.