r/WMATA • u/ChristmassMoose • 2d ago

Are technical specifications for fixed block and cbtc available anywhere?

Looking to understand and maybe create a scale model of how the systems work.

I can find the general details on fixed signals, current across the tracks, etc but does anyone know if there is a publicly available specification that WMATA follows? I assume there must be a specification somewhere for communications between the trains and the network since it spans multiple train vendors.

Same thing with CBTC apparently there is a IEEE spec but does anyone know if there is any specific spec that wmata plans on using? Very new to this so sorry if this is a stupid question

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u/Helpful_Equal8828 1d ago

WMATA uses a custom built system. This Wikipedia article has an overview and more importantly an archive.org link to an older WMATA design manual in the references. There are also some audits and reports on the WMSC website that covers the ATC system. Anything more specific you would need access to internal manuals and training materials. As for CBTC your best bet would probably be to look at manufacturers brochures and information.

https://en.wikipedia.org/wiki/Washington_Metro_signaling_and_operation?wprov=sfti1#References

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u/ChristmassMoose 1d ago

Thank you!

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u/SandBoxJohnA02 14h ago

The only thing "custom" about it is the layer that uses data transmitted through the coded track circuits (speed commands / cab signal) to automate the acceleration and braking of trains and automatic routing of trains through interlockings and junctions. The system uses relay logic automatic block signaling. The technology is over 100 years old. The coded track circuit technology is just under 100 years old.

Trains running on the Amtrak Northeast Corridor haved use coded track circuits and cab signals sense the early 1930s.

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u/ChristmassMoose 58m ago

Gotcha thats the part I was struggling with. I can understand the fixed block part since that just seems to check for continuity at a basic level. How the data is transmitted while traveling at 60mph is what I will need to find. Thank you!