Key:railway:etms

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railway:etms
Description
Indicates whether a railway track is equipped with the Interoperable Electronic Train Management System (I-ETMS). Show/edit corresponding data item.
Group: railways
Used on these elements
should not be used on nodesmay be used on waysshould not be used on areasshould not be used on relations (except multipolygon relations)
Useful combination
Status: in use
More details at taginfo
Tools for this tag

Interoperable Electronic Train Management System (I-ETMS) is a safety-critical, communications-based Positive Train Control (PTC) system. Designed by Wabtec primarily for Class I freight railroads and passenger networks in North America, I-ETMS functions as an overlay system on top of existing signal, dispatch, and track infrastructure without replacing conventional signal systems or Automatic Train Control (ATC).

Core Purpose & Architecture

I-ETMS is designed to monitor train movement and automatically enforce safety limits to prevent:

  • Train-to-train collisions
  • Over-speed derailments
  • Incursions into established work zones
  • Movement through misaligned main line switches

The Four Segments

The architecture is split into four interacting segments:

  1. Office Segment:
    Centered on the Back Office Server (BOS). Manages track databases, processes dispatch updates, generates Temporary Speed Restrictions (TSRs), and issues track authorities.
  2. Communications Segment:
    Utilizes Interoperable Train Control Messaging (ITCM) over 220 MHz Data Radios (wayside/locomotive communication), cellular networks, and Wi-Fi (in-yard data downloads).
  3. Wayside Segment:
    Employs Wayside Interface Units (WIUs) installed at signals, switches, and hazard detectors to monitor physical state and broadcast telemetry directly to nearby trains.
  4. Locomotive Segment:
    Centered on the Train Management Computer (TMC) and Cab Display Unit (CDU) onboard. The TMC uses a 2-of-3 CPU voting system to execute target-distance warnings, penalty brake applications (service rate), and emergency brake enforcement if an overspeed or authority violation is predicted.


Tagging Usage

Main Track Tagging

Apply railway:etms=* directly to railway ways (railway=rail).

Key Value Description
railway:etms yes Railway track is equipped with operational I-ETMS.
railway:etms no Railway track is not equipped with I-ETMS.


Secondary Infrastructure Mapping

Physical assets monitored by the I-ETMS Wayside Segment are mapped on individual node or way elements along the line:

  • Signals: Mapped as nodes with railway=signal. Wayside interface support can be tagged with railway:signal:wiu=yes.
  • Switches / Turnouts: Mapped on junction nodes with railway=switch.
  • Mileposts: Mapped as nodes with railway=milestone and distance=* to match subdivision track profile reference points.
  • Operating Speed Limits: Maximum Authorized Speed (MAS) profiles referenced by I-ETMS back-office databases are recorded on track ways using maxspeed=* (e.g., maxspeed=60 mph or maxspeed:freight=45 mph).
  • Subdivision Information: Track corridors are grouped into relations using type=route + route=railway + ref=* or name=* to delineate dispatching territories.

System Combinations

I-ETMS is an overlay system and is frequently tagged alongside complementary safety technologies:

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