eveloping and Analyzing Automated Tests for Computer Based Interlocking System The Case of AA LRT
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Date
2016-06
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Addis Ababa University
Abstract
Railway system has safety, economic and environmentally critical system because its failure may cause serious
consequences of loss human life, serious injuries, and large scale of environmental damages or considerable
economical penalties. Therefore we have to guarantee that they are designed and put into operation properly. Thus,
no error can be tolerated in the operation of the system. Interlocking system is used for ensuring the safety of
trains. Interlocking systems control all wayside elements in railway traffic. These systems are accountable for safe
train operations and must prevent collisions and derailments of the train. Testing the interlocking systems is a key
focus. Before start the train operation must be test all equipment according to the interlocking law and safety
regulation. In general there are two type of testing approach in railway system that is manual and automatic. Both
have on their own advantage and disadvantage. Automation has two major benefits; it saves the verification time
and reduces the risk of manual errors. In order to verify whether an interlocking system is consistent with the
system requirement specification, it is necessary to carry out a series of testing.
In this thesis to verify the interlocking system use control tables, Boolean function, flowchart, a computer aided
tool for the generation of test cases is studied and implemented. A number of test purpose models have been
created to direct test case against the interlocking. These test purpose models were implemented in C sharp and Sql
server. The entire test setup can be run on any PC and does not require the interlocking hardware. This method can
be applies to a number of smaller interlocking systems and partly to the more complex of AALRT depot and
station.
Simulations have GUI to interacts the user with the system and enable easy visualization of the movement of the
train. The user can inject different possibility of testing mechanism. One testing mechanism was unavailable list of
Tracks or Switch interlocking elements. Other methods are using randomly occupied of Tracks and changing of
the switch position.
Result show that with 7 routing selected 21 conflicting and 64 derailment of the train are verified and validated.
The verification is comparing the expected result with the actual simulations. This simulations tools are used for
addition verification that support for AALRT.
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Keywords
Computer Based Interlocking system, Control Table, Flow Chart, C Sharp, SQL server