IEEE 1474-4:2011 pdf free download – IEEE Recommended Practice for Functional Testing of a Communications-Based Train Control(CBTC) System
4.1.1 Train location determination, independent of track circuits
With train location determination independent of fixed-block track circuits,alternative control strategiesbecome possible(where movement authority limits are not constrained by physical fixed-block track circuitboundaries) that should be reflected in the CBTC functional test process. Certain test practices for fixed-block, track circuit-based signaling systems may no longer be applicable or practicable, and alternative testprocedures are necessary to reflect the specific principles of operation of CBTC systems.
4.1.2 Bidirectional train-to-wayside data communications
The performance and availability of a geographically continuous train-to-wayside and wayside-to-train datacommunications network is critical to CBTC operations.Hence, as an clement of the system levelfunctional testing,the network performance and availability (including network stability，data-linkbandwidth，and message latency) should be verified,supported by analysis,as necessary, of worse-caseconditions that cannot be easily duplicated in the factory or in the field.
4.1.3 Train-borne and wayside vital processors
The distributed CBTC wayside and train-borne vital processors that process the train status and control dataand provide continuous automatic train protection (ATP), automatic train operation (ATO), and automatictrain supervision (ATS) functions are typically highly integrated.As a consequence, the final functionaltesting can only be performed at a systems level with all major CBTC subsystems operational and withmultiple vehicies operating.CBTC systems also typically include significant levels of equipmentredundancy to achieve the high system availability required. The need to verify the overall stability of sucha distributed computer system and the need to verify switchover capabilities between redundant sets ofwayside andor train-borne CBTC equipment also should be reflected in the functional test process.
CBTC systems—typical of other advanced technology systems—are software/database driven. In suchcomplex software-based systems it is important to understand that whereas the majority of softwaredevelopment often occurs prior to field testing,the software development process does not end until thesystem is verified to be operating correctly in the field.Multiple software releases are also typicallyrequired in a given application (specifically for complex cut-overs in a resignaling application) resulting ina need for a defined level of regression testing following each software update.
4.1.4 Application-specific requirements
The correctness of application-specific data (i.e.， infrastructure data，such as curves，grades，stationlocations, etc., and train-specific data, such as braking rates and response times, etc.) and that this data hasbeen correctly implemented within the system databases,should also be verified as an element of thefunctional test process.
When resignaling with a CBTC system，application-specific external (legacy) equipment interfaces,application-specific operating modes,and application-specific functional requirements are common.Thiscan result in application-specific designs that should be reflected in the application-specific functional testprocess. To exploit the operational capabilities of CBTC systems，the design of a CBTC system is oftenintegrated with the design of other fixed operating elements of a rapid transit system such as traction powersystems, tunnel and station ventilation systems, passenger information and security systems, and backbonecommunications networks，for example. In addition,the designs of the onboard train location/speedmeasurement subsystems are also often application-specific due to vehicle-specific interfaces. As such, theperformance of these application-specific designs should be verified through the functional test process.