Advanced Train Administration and Communications System (ATACS) is an

automatic train control Automatic train control (ATC) is a general class of train protection systems for railways that involves a speed control mechanism in response to external inputs. For example, a system could effect an emergency brake application if the driver do ...

(ATC) system developed by

RTRI , or , is the technical research company under the Japan Railways group of companies. Overview RTRI was established in its current form in 1986 just before Japanese National Railways (JNR) was privatised and split into separate JR group compan ...

starting from 1995 and first introduced by

JR East The is a major passenger railway company in Japan and the largest of the seven Japan Railways Group companies. The company name is officially abbreviated as JR-EAST or JR East in English, and as in Japanese. The company's headquarters are in ...

on the

Senseki Line The is a railway line in Miyagi Prefecture, Japan, owned and operated by the East Japan Railway Company (JR East). It connects Aoba-dōri Station in Sendai to Ishinomaki Station in Ishinomaki, and provides access to the central coast areas of ...

in 2011. It uses radio communication rather than traditional

signals A signal is both the process and the result of Signal transmission, transmission of data over some transmission media, media accomplished by embedding some variation. Signals are important in multiple subject fields including signal processin ...

, and works as a

moving block In railway signalling, a moving block is a signalling block system where the blocks are defined in real time by computers as safe zones around each train. This requires both knowledge of the exact location and speed of all trains at any given t ...

system.

Technical description

Radio transmission

Communication between the train and the trackside equipment happens entirely through bidirectional radio communication. Radio base stations are placed at intervals of 2 to 3 km and operates on four different frequency bands, used alternately to prevent inference. Radios operate in the 400 MHz frequency band, with data transmitted using TDMA access method with

Reed–Solomon error correction In information theory and coding theory, Reed–Solomon codes are a group of error-correcting codes that were introduced by Irving S. Reed and Gustave Solomon in 1960. They have many applications, including consumer technologies such as MiniDiscs, ...

at 9.6 kbps. The radio system are based on proprietary standards with encryption.

Ground equipment

Ground controller

The ground controller, being the main control unit of ground equipment, is responsible for the identification of train locations based on information received from the trains, route setting, control and interlocking, train interval regulation, and boundary control and train entry/exit handover.

Train existence supervision equipment

Connected to the ground controller, the train existence supervision equipment is responsible for controlling line occupation of trains. It also maintains safety in case of system failure and during recovery operations by using train identification assigned to each trains to track occupation even if other equipment is out of service.

System supervision equipment

The system supervision equipment monitors the operating status of the ATACS system and has functions to change settings such as temporary speed limits in increments of 5 km/h. The system supervision equipment is also responsible for setting track closures, setting

single-line working On a railway, single-line workingDriver's Rulebook: Modul ...

, and routing maintenance vehicles.

Field controller

The field controller connects trackside equipment such as switches, level crossing equipment, radio stations, and detectors to the ground controller.

Onboard devices

Every train is equipped with an onboard device which is responsible for determining the train's position. For more precise position tracking, a

balise A balise ( ) is an electronic beacon or transponder placed between the rails of a railway as part of an automatic train protection (ATP) system. The French word '' balise'' is used to distinguish these beacons from other kinds of beacons. Bali ...

is installed every kilometer. This information, along with the train length is periodically transferred to the ground equipment. Therefore, no

track circuit A track circuit is an electrical device used to prove the absence of a train on a block of rail tracks to control railway signals. An alternative to track circuits are axle counters. Principles and operation The basic principle behind the t ...

s or

axle counter An axle counter is a system used in railway signalling to detect the clear or occupied status of a specified section of track. The system generally consists of a wheel sensor (one for each end of the section) and an evaluation unit for counting ...

s are necessary. The onboard device is also responsible for calculating the brake intervention curve required to stop the train at the limit of the limited movement authority (LMA), the area in which the train is permitted to move. It takes the individual train's braking performance, track gradient, curve, and speed limit into consideration to perform this calculation. Similar to earlier

Automatic Train Control Automatic train control (ATC) is a general class of train protection systems for railways that involves a speed control mechanism in response to external inputs. For example, a system could effect an emergency brake application if the driver do ...

systems, ATACS uses

cab signalling Cab signalling is a railroad, railway safety system that communicates track status and condition information to the cab (locomotive), cab, crew compartment or driver's compartment of a locomotive, railcar or multiple unit. The information is con ...

. A cab display shows ATACS information required for driving, such as the distance to limit of the LMA, the maximum allowable speed as permitted by the brake curve, and the route set.

Similar systems

ATACS has been compared to ETCS Level 3

Usage

ATACS is deployed on the following lines: *

(with

ATS-Ps Automatic train stop or ATS is a system on a train that automatically stops a train if certain situations occur (unresponsive train operator, earthquake, disconnected rail, train running over a stop signal, etc.) to prevent accidents. In some scen ...

as fallback) *

Saikyō Line The Saikyō Line () is a Japanese railway line operated by the East Japan Railway Company (JR East). It connects Ōsaki Station in Shinagawa, Tokyo, and Ōmiya Station (Saitama), Ōmiya Station in Saitama Prefecture. The line's name is a portmant ...

(

Ikebukuro is a commercial and entertainment district in Toshima, Tokyo, Japan. Toshima ward offices, Ikebukuro Station, and several shops, restaurants, and department stores are located within city limits. Transportation At the center of Ikebukuro is ...

– Ōmiya, as replacement for ATC-6) *

Koumi Line The is a railway line in Japan operated by East Japan Railway Company (JR East). It links Kobuchizawa Station in Hokuto, Yamanashi with Komoro Station in Komoro, Nagano, and extends 78.9 km (49.0 mi) through the mountains with a total ...

Notes

References

Rail transport in Japan Train protection systems {{Japan-rail-transport-stub