Occupancy Detection and Blocks

[tarnett]

Hi all,

I am currently in the design phase of an N&W/NS Pocahontas division based double track HO railroad. I wish to implement occupancy detection with signals and am currently determining the blocks. I do stumble when I come to the crossovers. As such on the N&W on said division, the signals for crossovers are located prior to the crossover itself, which leads me to beleive that a block ends/begins at said point.

The enclosed image (link) indicates the blocks (thus far) by solid red and blue lines. Notice that I have left the crossovers void of solid lines. My question is which part or parts of the crossover would be assigned to any of the indicated blocks? Is it possible that the crossover is a block all to itself? Any help would be greatly appreciated.

http://tarnett.rrpicturearchives.net/showPicture.aspx?id=2158864

Regards,

Todd Arnett

[gandydancer19]

 Crossovers are usually a block or two by themselves and are called OS (on switch) sections.  This is to help prevent an operator from throwing the switch under a train.  I have a single crossover with each turnout a separate block.  I also linked them into the running track block.

For the crossover you show, I would make the upper two turnouts one block and the lower two turnouts, including the track connecting them, a second block.  Then in your control program, you can link each one of them to the beginning of one of the regular track occupancy blocks.   The crossovers would also be protected by its own signals and these may also linked into the occupancy blocks.  Ideally, you don't want to make these short blocks an indicated block by themselves.  They would be too short to protect a train.

The signals would indicate the position of the route, as determined by the turnout position, and also indicate the condition of the block ahead.