Context
Since their inception trains have always needed a way to know that it’s safe to travel ahead, as they travel at such speed and take so long to stop. In the industrial revolution, the lever frame system and the role of the signaller were invented. The system put a signaller in charge of a section of railway, with a set of large mechanical levers in front of them to mark different sections of the railway as safe to enter. This first signalling system was purely mechanical. Over time different parts of the system would be innovated on and electrified. But there are some notable times in history so far that have seen the signalling system step up to meet modern standards, such as the step to a switchboard panel in the 70s/80s, and then the step to VDU-based systems in the 90s/00s.
Most railway signalling nowadays is controlled from a signalling centre, where signallers control their areas from VDU workstations alongside others. There are three common signalling systems in the UK which use a variation of a tracker ball or mouse and keyboard as their input method.
The development of signalling systems from mechanical to today
Brief
Alstom contracted Mima to aid in the development of a signalling system fit for the 21st century; another historical step change in the world of rail control.
MCS Infinity changes everything. By providing the signaller with a touchscreen and a large array of ultra-wide curved screens the user has a smarter, more intuitive control system that eliminates the need for paper-based forms.
Our task at Mima was to assist in the UX of the workstation, both in the physical set up and the digital interfaces, and plan and execute an integrated process of usability testing and approvals.
This was a development project by Alstom, who were ultimately aiming to have the system approved for use by Network Rail, who oversee the railways in the UK. Once approved, control centres across the country would be able to purchase MCS Infinity when upgrading their equipment.
Activities
Due to the national importance of this product, we began by outlining a strict roadmap of research activities to feed the development programme. The planning work defined how users would be involved in the design process, how the system would be rigorously tested, and how the project would ensure the system is fit for purpose and accepted by Network Rail.
The project established a user group of experienced signallers that were called upon when referential signalling know-how was required. Most notably, the user group helped create a set of scenarios that effectively encompass all of the use cases of a signalling system. This was vital as it enabled us to conduct a scenario-based task analysis, which drew out all the activities that the signaller must complete in either a normal signalling setting or when faced with a problem they must resolve. Moreover, this set of scenarios enabled us to formulate our assessment strategy to make sure that all parts of the system are rigorously tested for usability.
I made sure the project maintained a human-centred approach by adopting the principles of international HMI standards. In particular, ISO 9241-210 actually states ‘usability’ can actually be broken down into three sub attributes of effectiveness, efficiency and satisfaction. Breaking usability down like this enables us to create interview questions that dig deeper into what it means for a system to be usable, and makes our results more reliable. I planned the sessions to cover a 3 hour period, to reflect a signalling shift. We asked the signallers to operate the control area as they normally would, but we periodically simulated one of the operational scenarios for the signaller to resolve. The signallers’ response to these scenarios, in comparison to their response using existing system, determined the usability of the new Infinity system.
We conducted our testing at the three signalling centres that were to be the first implementations of MCS Infinity. At the time of my exit from the project, we had completed three rounds of formative usability testing and made the structured plan for more rounds of summative testing, which were subsequently carried out by my colleague.
Outcomes
After a long and thorough process, Mima saw the system through to full approval. Last year, the project enabled Alstom to be awarded a turnkey project for the value of £49 million.
One of the reasons for the success of the project was the philosophy of continuous learning we had at Mima. To embody this in the project, we undertook retrospective activities at several points in the project, which enabled us to ensure we were on the correct path at each point, as new information and requirements surfaced. Ultimately, this proved imperative to deliver the quality needed for such a safety-critical system. I took over as team leader on this project before testing began, and I enjoyed liaising to organise the assessments, meeting the users and getting their feedback.