Mahtab Ibnazia

An ECSA registered professional engineer with comprehensive knowledge of the train authorisation (signalling) system. Signalling systems are safety-critical systems which require the highest safety integrity level (SIL4) technologies. As a senior engineer at Transnet, I am responsible for specifying, designing, developing, assessing, and approving the fail-safe signalling systems.

Railway signalling has presented me with the actual real-world experience of systems engineering and granted me an opportunity to gain an overall understanding of all the components that integrate for the complete system to operate successfully.

Besides having the insights of systems engineering, I am also involved with solving the software engineering problems. As much as my current profession mostly requires from me to work with hardware systems. However, I kept myself involved in software development tasks using C# and C++ programming languages.

Some of the most complex software concepts were learnt while working with programming languages, such as object-oriented programming, polymorphism, serialisation, etc. Technically competent to analyse complex engineering design and capable of providing leadership, planning, direction, and technical expertise to manage complex engineering tasks. While working on projects, I learnt to be flexible and adaptable to the environment depending on the project needs.

Working as a senior signalling engineer in the Transnet Technology Management department, where my primary responsibility is to type-approve the new technologies for the railway organisation. Some of the core activities as a senior engineer are given below:

• Responsible for providing support to the organisation on the railway signalling interlocking system.
• Responsible for approving the latest signalling interlocking related technologies to use within the Transnet railway network. The approval process includes drafting specification, tender evaluation, approval of design, factory & site evaluation of the technologies and monitoring the pilot process.
• Drafted and reviewed various specifications of signalling components, such as primary, and secondary interlocking relays, axle counting system, fail-safe data transmission, electronic interlocking, relay-based spoorplan interlocking, level crossing system, etc.
• Have experience in relay-based spoorplan interlockings, e.g., Mk1, Mk1a, Mk1b and Mk1c, as well as in electronic interlockings, e.g., Thales ESRW L90 5, Microlok MLK II, etc.
• Drafted highly technical complex specifications, such as, user requirement specification (URS) for Electronic Interlocking Interface to Relay-Based Spoorplan Interlocking. 
• Have been involved in projects that gave exposure on some of the complex interlocking such as, Hybrid interlocking (HRS) and Relay-Based interlocking (MkM).
• Reviewed and approved the modification of the hybrid interlocking (HRS) design to extend the loop length of the existing station. 
• Responsible for the type-approval of the level crossing (LX) system, which integrates with the intricate interlocking of the station's existing infrastructure.
• A thorough analysis of Communication Based Train Control (CBTC) signalling, including Positive Train Control (PTC), European Train Control System (ETCS Level 2 & Level 3), On Board Computer (OBC), and Automatic Train Protection (ATP) systems, was conducted to provide input for the ConOps document for the in-cab signalling system.
• Prepared technical and functional specifications for signalling systems or sub-system, such as, Repair and Refurbishment of Interlocking Units
• Performed type approval testing of the new technologies, for example, validating the safety case of the new yard automation system for the use of Transnet yards. 
• Conducted acceptance tests of the technologies including FMECA analysis for the safety of the systems.
• Prepared the acceptance testing report that incorporated FMECA results, Functional test results and snag-lists. 
• Collaborated with the OEM for alteration and modification of the technologies that are better suitable for the Transnet network.
• Ensured the OEM adhere to the required operational capabilities (ROC) for quality control of the supplied products.
• Responsible for the different phases of approval of the technologies/systems, such as, concept approval, detail design approval, approval for construction and final testing & commissioning approval, etc.
• Reviewed and provided concept approval of signalling drawings for the concept design submission to Railway Safety Regulator (RSR) and proto-type development. 
• Provided the final approval once the acceptance test was conducted and ready for site installation.
• Constantly communicated with the end user - Rail Network Maintenance – to obtain feedback regarding the new technologies.
• Provided consulting service to the network owner and the maintainer regarding the possible upgrades of existing networks using new technologies. 
• Audited the existing railway network and prepared a feedback report with recommendations of improvements for the organisation. 
• Have been involved in tender evaluation as a technical expert where technologies and systems were measured as per the compliance checklist. 
• Responsible for preparing the clause-by-clause compliance checklist for tender evaluation.
• Provided technical assistance as and when requested by the maintenance team on equipment failures. 
• Analysed the root cause of the equipment failure and determined the appropriate solution of the problem.
• Applied a practical solution of the problem without compromising the safety of the system while ensuring the most cost-effective solution was implemented due to budget constraint.
• Have been part of the Board of Inquiry (BOI) of railway incidents as a signalling expert where I was responsible for finding the root cause of the accident and providing recommendations to avoid reoccurrence of the incidents.

The control table is the most essential document that specifies all the safe movements of the trains on the railway track and prevents any possible conflicting movement of trains on the railway track. The research focuses on the automatic generation of the control table using a compositional approach. Conventionally the control table is generated by linking the railway signalling elements together according to their geographical position in the station layout and developing algorithms that produce the conditions of the control table.

In the compositional approach the large station is divided in sub-sections and algorithms are developed to produce the conditions of the control table using these sub-sections.

Software algorithms are developed for both the approaches using C# programming language. These algorithms are applied on several station layouts by gradually increasing the size and complexity of the station layouts. In data structure the algorithm efficiency is measured in terms of the complexity of the algorithm.

A theoretical and an experimental analysis were conducted to measure the algorithm complexity. A statistical analysis was performed to gain comprehensive understanding on the use of computational resources, such as, the execution time and memory usage. It is transpired through the experimental results that generating the control tables using compositional approach is more efficient than the conventional approach for the station layouts.