The Track Transit System Upgrade
The Stansted Airport Track Transit System (TTS) is an automated people mover system that carries passengers between the main terminal building and two remote Satellite buildings. The system came into service in 1991 and operates on 2km of elevated and tunnelled guideway.
Firstco specialise in developing mission critical control solutions using open and commercial off the shelf technologies (COTS). Because of this, we were engaged to replace key components of the existing system that were considered obsolete, namely the central control system and the control room operator interface.
The fundamentals of the project were to:
- Minimise disruption to the operational service of the existing TTS
- Develop a programme to de-risk the likelihood of failure of the existing system
- Utilise COTS components
- Provide a highly resilient, reliable and open system solution
Firstco have delivered for us operators a user-friendly, simple and operationally easier system to run.
- Paul Norton, Stansted TTS Operator & Trainer
Solution and Challenges
A Supervisory Control and Data Acquisition (SCADA) system replaced the existing operator interface. The key to providing a user interface that the operator could use effectively was to engage the operators and relevant stakeholders in a series of workshops.
The SCADA design encompassed:
- The nature of the task, workload, the working environment/work station, the design of displays and controls – solutions were designed in accordance with ergonomic principles to take account of both human limitations and strengths, both physical and mental.
- The individual – including his/her competence, skills, personality, colour vision, attitude and risk perception.
- The workplace – including work patterns, the culture of the workplace, resources, communications and leadership.
The finished product provides operational control and monitoring functionality that the operator finds intuitive and user-friendly. The entire alarm system was re-evaluated and popups were employed to aid the operator in decision making, especially in emergency and critical situations.
In addition to the operator interface, the system interfaces to a number of existing TTS critical subsystems, namely:
- Automatic Train Operation (ATO) station computers via the Bitbus network
- Operational Radio System (ORS) via an RS232 interface
- Interlocking System (including Local Control Panel (LCP))
- Power Distribution System (PDS)
Operator & Stakeholder Engagement
Throughout the project lifecycle, TTS maintainers and operators were engaged and took an active role in reviewing the system design and ensuring that it is fit for purpose from a maintainability and operational point of view.
During the testing phases TTS operators and maintainers assisted in carrying out the integrated system tests alongside Firstco.
Operator training was also crucial to the success of the project. To expedite operator training and to expose and familiarise them with the new SCADA system, a full simulator was developed. The simulator also provided replay functions to allow the system to replay real events for both training and investigative purposes.
Outcomes
The project releases Stansted Airport from dependency on the original manufacturer for future upgrades and maintenance.
As a COTS open system solution any competent software house can be appointed for changes or maintenance in the future. This represents a huge cost saving over the remaining life expectancy of the system.
In addition to financial gains, the new system is now highly flexible and scalable, allowing many other systems to be integrated into the new SCADA.
Most importantly is that the safety features are now much more operator-friendly, providing guidance and reminders via context sensitive pop-ups to ensure correct procedural decisions are made and are in accordance with corporate philosophy.
