The report at scientific and practical conference «Perspectives of implementation of means of traffic safety on the railways of Ukraine». Khmelnik, Vinytsia Region, 2010.

Electronic axle counting system

OverviewThe main directions causing maximum efficiency of upgrade of technical devices, are:

• replacement out-of-date and optimization of the new station and trackside assets;
• monitoring and control of train operations from integrated centers of the supervisory control;
• implementation of microprocessor based devices for the maximum reduction of operational and construction expenses.

Upgrade of technical devices shall be carried out by way of reducing of their number and by carrying out the following actions:

• replacement of the out-of-date EC systems by MPI or their upgrading by hybrid option;
• replacement of exploited systems of train separation by systems using counters of axles and an automatic locomotive signaling with point wise communication links (ALS-PWCL);
• Implementation of centralized control system.

 It is known that the major element practically of all systems of railway automatic equipment providing traffic safety of trains, are rail circuits. They serve as primary information source about a status of controlled sections of rail track. However due to several of objective reasons (low resistance of the ballast, limited length, absence of possibility to isolate rails from bridge constructions, considerable operational costs etc.) it is sometimes technically inexpedient to use rail circuits.Monitoring of the free status of such track sections can be also realized on principle of counting of wheel pairs entering and quitting from a section. Systems of axle counting are intended for operation as a part of systems of railway automation and supervision at railway transport of the main lines and on specialized ways (industrial transport), for monitoring of clearance (occupancy) of multiple and non-branched tracks at stations and runs of any kind of trains traction.

Systems of axle counting of rolling stock give the chance to count automatically the axles of a rolling stock passing through certain points of station in any direction and for any time frame, and also to archive this data. It will allow obtaining information on quantity of the cars being at any time and on any sections of a way, for example: at receiving-departure yards, point switch free sections in neck yards, stud tracks, on runs.Axle counters are recommended to implementation:

• when there is impossibility or economic inexpediency of use of rail circuits of different types in connection with low resistance of a ballast;
• when metal sleepers are used;
• dirtiness of rail heads;
• hindering influence of a tractive contact network, plants or power lines, etc.

In some cases counters of axles can be applied along with rail circuits.Axle counting system provides:

• continuous monitoring of a status empty track  and point switches sections of any configuration, whilst integrity of rail lines isn’t supervised;

• steady operation of apparatus when switching of feeders of power supply;
• possibility of selective forced restoration of the initial status of apparatus of devices of system of the axles counting after maintenance works, replacement of equipment or after failure of its operation;
• possibility of arrangement of collection and accumulation of data about operation of equipment, registration of events and statuses of controlled track sections and point switch sections by means of any personal computer.

Today there are following technical solutions of axle counting:

• at runs equipped with semi-automatic interlocking (including in case of DI of low-traffic lines), for monitoring of vacancy of run, check of arrival of train in full strength and automatic formation of a block-signal “track arrival”;
• at runs equipped with automatic interlock for monitoring of vacancy of separate sections with detour or metal bridges where insulation of rails from elements of clear span structures isn’t provided;
• at stations equipped with EC or devices of key interlocking of switchers and signals, for monitoring of vacancy of branched and non-branched sections of station tracks;
• at crossing runs in case of the PAL and AL equipped with a crossing signalization, for monitoring of vacancy of sections of notification to moving and fixing of the direction of movement and train passage.

when the station is equipped with devices of axle counting system then there is not required installation of insulating joints and the choke transformers on boundaries of uncodable track and switch sections.At stations with electrical traction to provide plumbing of a traction current, conductor bonds and electro tractive connectors are installed.Conductor bonds and switch point connectors can be avoided in case of self-consistent traction (except codable sections).Due to axles counting devices don’t supervise integrity of rail lines, and in absence of rail circuits, as a rule, it is impossible to realize coding of tracks by ALSN codes, implementation of axle counters on the main way of stations, ways of the non-stop run and tracks of shuttle and passenger trains traffic, as well as at runs equipped with self locking is inexpedient to apply.When necessary at track sections without rail circuits coding by ALSN codes can be executed by means of a loop (loops), laid down near rails. The maximum length of a loop is recommended to take no more than 250 …300 m. In case of bigger length of a section of tracks it is necessary to use several loops connecting through separate code transformers.The exception of maintenance of the rail circuits which are the reason of 30-40 % of all failures of SCB devices will lead to reducing of delays and idles of rolling stock, increasing of a turn of coaches and locomotives, improving of traffic safety of trains. Operational costs for cutting of ballast, for changeover and the maintenance of elements of insulation of rail lines and bonds, including expenditures for maintenance of rail cars for a welding of bonds (combustive-lubricating materials, repair, workers’ wages) are thus excluded.

Features of axle counting system.

Main parameters of axle counting system:

• speed of trains on supervised sections from 0…250 km/h;
• operation temperature range  – 40…+85 С°;
• range of authentic information transfer between points of the axle counting and EC post no more than 10 km;
• power consumption no more than 10 VA.

In general system includes (Fig.1):

• post of axle counting (PAC);
• track side electronic module (TSEM);
• cable communication line (CCL);
• post of decision making device (PDMD);
• track relays (TR);
• post of forced regeneration of initial status of axle counting apparatus (PFRS);
• uninterrupted power supply source (UPS).

Fig.1. Structural diagram of station axle counting system

Axle counting posts are designed for receiving of primary data related to number of axle of rolling staff (considering direction of movement), within the limits of sections controlled by system and transfer of data to post computing device. PAC are located in the boundaries of station tracks and switch sections controlled by devices and within the boundaries of approach sections. Each PAC includes track sensor and track side electronic module.Track sensor design generates electric signals when the rolling staff passes over it.Track side electronic module designed for counting of axles of rolling staff passed throug, taking into account direction of tracking, and transfer of this data to post computing device. Beside it controls the trouble free operation of track sensor and its correct position relatively to rail head.

Operation sequence:

During passing by of rolling staff track sensor of axle counting post forms electric signals, which bear information of fact of axle traveling and track direction. Signals of track sensor are incoming through cable to track side electronic module (TSEM), which counts the number of axles fixed by sensor, taking into account the direction of travel.Post computing device, continuously, sequentially inquires axle counting post, which after receiving inquire, transfer data of number of traveled axles to PDMD. Post computing device processes obtained data and controls operation of track relays.During operation process each TSEM is continuously self-tested and supervises performance of track sensor, as well as its correct position relatively to rail. In case of failure or unauthorized dismantling of sensor TSEM transits in protecting status, what bears cutoff of track relay at EI post.In case of failure of any counting post, track relays of track sections adjacent to it will remain without power after factual leaving (emptying) of such section by rolling staff. For removing of false occupation of track and switching sections there is a provision for panel of forced regeneration of initial status of axle counting devices (PFRIS) This panel has a group (junction) button of forced regeneration and individual buttons for each track section and switch section.

Economic efficiency of axle counting system is reached by:

• Cost reduction of equipment and saving expenditures for maintaining of SCB devices and track superstructure;

• Avoiding of cooper containing components (transformers, cooper busses) and as a result expenditures arisen because of thefts;

• Capability of control of sections with zero ballast resistance, metal bridges, and runs as whole for transfer of information into PI.