WMATA ATC Track Circuits

• WMATA utilizes an Automatic Train Control system to safely space trains on the railroad
• ATC breaks the railroad up into a series of blocks several hundred of feet in length
• This repository lists all (or near-all) ATC track circuits across the revenue WMATA Metrorail network

Where is this data from?

The data was obtained by Stephen Repetski on behalf of Greater Greater Washington/Rail Transit Ops in a PARP request.

Data Contents

The following partial dataset from WMATA includes four columns descriptive of the ATC track circuits which make up the railroad:

• TRKLEN - the length of each track circuit; NOTE: The dataset appears to have some minor errors, so TRKLEN does not always match up to the summation of FROM_MEASURE and TO_MEASURE
• Track Name - the name of the track that the circuit is on
• FROM_MEASURE - the starting point of the track circuit, in feet
• TO_MEASURE - the ending point of the track circuit, in feet

What is Automatic Train Control?

WMATA has some good documentation online that goes into great detail about what ATC is.

Greater Greater Washington similarly has a quick primer about how ATC track circuits work within Metrorail to keep trains separated.

Why are there no circuit IDs?

Each circuit is typically identified by a concatenation of the Track Name and the initial From Measurement (divided by 100 and rounded off). For instance the circuit on J1 with FROM_MEASURE 86295 would have an ID of J1-863.

however

This is not the case wherever interlockings on the railroad exist. Due to the switches which cross from one track to another, there are extra circuits in those areas with a different naming convention. Those interlocking circuit names are not included in the data provided by WMATA.

Interlockings

I will not attempt to include all circuit IDs here, but you are welcome to if you'd like (fork and submit a PR, if you dare! ;) A typical interlocking includes 4 switches - 1A, 1B, 3A, and 3B - and each numbered pair sits diagonal from its mate. Circuits in interlockings follow a naming convention like: 1BT and 3BT. However, as is the case, this doesn't hold for larger interlockings where there are pocket tracks, or other types of turnouts.