Description
On-board Automatic Train Protection (OATP) is a service defined within the 3GPP framework for railway and critical communications, specifically as part of the Future Railway Mobile Communication System (FRMCS) which is the successor to GSM-R. OATP refers to the on-board subsystem responsible for receiving, processing, and acting upon automatic train protection commands. It works by establishing reliable, low-latency communication links between the train and trackside control systems via a 3GPP mobile network (e.g., 4G LTE or 5G). Key components include the On-board Unit (OBU) with its communication module, the Vital Computer responsible for safety-critical processing, and interfaces to the train's braking and propulsion systems. The OATP service receives Movement Authorities (MAs) and other safety-critical data from the Radio Block Centre (RBC) or interlocking. It continuously monitors the train's speed and position, comparing them against the received movement authority profile. If the train is in danger of exceeding its authority or safe speed, the OATP system autonomously initiates a brake application to enforce safety. Its role is to provide a continuous, fail-safe overlay protection system that enhances or replaces traditional fixed-block track circuits and lineside signals, enabling higher capacity and more flexible operations.
Purpose & Motivation
OATP was created to modernize railway signaling and control by leveraging standardized cellular technology, moving beyond the legacy, voice-centric GSM-R system. It addresses the limitations of traditional systems, which are often based on fixed infrastructure with high installation and maintenance costs, and limited data capabilities. The primary problem OATP solves is the need for a high-performance, data-centric communication system for safety-critical train control to support advanced operational concepts like moving block signaling and higher degrees of automation. Its creation was motivated by the global railway industry's need for increased line capacity, improved operational efficiency, and enhanced safety, all while transitioning to a future-proof, IP-based communication standard (FRMCS) that can utilize commercial mobile network advancements. OATP enables the realization of Communication-Based Train Control (CBTC) and ETCS Level 3 over cellular networks.
Detected Changes Across Releases
from 3GPP Change RequestsSpecific changes extracted from the „Change history“ tables of 3GPP specifications (8 CRs across 3 releases). Complements the general historical overview above with the evidence-based evolution of this function.
Studied in Rel-16, normative work from Rel-18.
In Release 18, the OATP (On-board Automatic Train Protection) function introduced an "Arbitration: automatic answer" capability. This new feature automates the response process within critical train communication systems, enhancing operational efficiency for FRMCS Users like Drivers and Controllers during multi-train voice communications. The automatic answer mechanism is managed by the system's authorisation and prioritisation applications to ensure timely and reliable establishment of safety-related calls.
- Arbitration: automatic answer TS 22.989CR0009
In Release 19, the OATP (On-board Automatic Train Protection) function was enhanced with new use cases for Multi-train voice communication for Drivers and Ground FRMCS User(s), including specific procedures for its initiation and termination. These enhancements introduced capabilities for the FRMCS System to dynamically add or remove users from the communication, manage application layer priority and precedence, and present the location of Drivers to Ground FRMCS Users during a call. Additionally, the release defined the setup time and the requirement for multi-user talker control within these critical group communications.
In Release 20, the OATP (On-board Automatic Train Protection) function was enhanced with new use cases and updated requirements for multi-train voice communications using the FRMCS system. Specifically, new procedures were introduced for both Train Controllers (Ground FRMCS users) and Train Drivers (Mobile FRMCS users) to merge two separate multi-train voice communications and for a driver to take over an Ad hoc Group Call from another FRMCS device. Furthermore, the release included a comprehensive update of the requirements and gap analysis for these multi-train voice communications, focusing on Ad hoc Group Communications for Drivers and Ground FRMCS users.
- New use cases: Merging of two multi-train voice communications by Train Controller (Ground FRMCS user) TS 22.989CR0033
- New use cases: Merging of two multi-train voice communications by the train driver TS 22.989CR0037
- New use case: Train driver takes-over an Ad hoc Group Call from another FRMCS device TS 22.989CR0036
- Update of requirements and gap analysis for multi-train voice communication for Drivers and Ground FRMCS User(s) using Ad hoc Group Communications TS 22.989CR0032
Explore further
Broader topics and technologies where OATP plays a role.
Defining Specifications
3GPP specifications that define or reference OATP, with the latest known release. Sourced from the 3GPP document catalog — see methodology.
| Specification | Title | Release |
|---|---|---|
| TR 22.889 vh40 | FRMCS Study; Stage 1 | Rel-17 |
| TR 22.989 vk30 | FRMCS Analysis and Requirements | Rel-20 |