Computerized System Integrity Tester (SIT)

System Integrity Test is conducted on Railway Signalling Systems to ensure Safety & Availability. The test is highly automated by which human errors are eliminated. Evidence of test results is produced for further validation, if required.


Testing of Signalling System for compliance to TOC / RCC is mandatory before commissioning of any signalling system. After commissioning also this test is required to be carried out periodically once in 3 years. First test is offline and the second one is online.

Implementation of interlocking (based on SIP) has the following stages

  • Preparation of Route Control Chart (RCC)
  • Design of logic circuits
  • Wiring of logic circuit
  • Testing and commissioning

We have automated the testing by which it is possible to find the mistakes in last 3 stages i.e. Design and Wiring of circuits and Testing.

  • The conventional (manual) system has the following limitations
  • Test procedure is not fully defined
  • No document of Testing (Test plan)
  • No evidence of Test Results
  • No evidence of validation of test results
  • No scope for verification of tests done, since no tangible output, results out of testing




  • Negative test of controlling functions
  • One Signal One Train Test
  • Route Checking Test (In Offline only)
  • Route release test - light engine and long train
  • Test for route locking
  • Test for back locking or route holding
  • Test for approach locking
  • Red-lamp protection test
  • Aspect sequence control test
  • Lamp cascading test
  • Point track locking test
  • SMKEY locking test for different assets
  • Crank handle and LX Gate locking test
  • Square sheet test(In Offline only)
  • Point Operation in Route Test (In Route setting type Panels Only)


  • Representation of Table Of Control in terms of data logger inputs
  • Instructions for carrying out tests are defined
  • Tests are converted to a software program based on Table of Control
  • Desirable test results are generated by software program based on Table Of Control
  • Online test results are compared with desirable results through software program
  • Status of the required relays are taken by the system from Data logger


Railway Signal Interlocking testing in Online & Offline for

  • Panel Interlocking ( PI )
  • Route Relay Interlocking (RRI)
  • Solid State Interlocking (SSI) / EI



System Integrity Tester Brochure

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