One of the most interesting parts of the Metro Tunnel project is the new signalling system. Consequently, the software engineers working on the system had many visitors interested to know about the project. But the system is quite complex to explain and most of the visitors were not engineers.
The problem was to illustrate the system in a way that helped with the explanations given to visitors. Software labs tend to be rooms with lots of grunty computers in them and not much to see so the schematic also needed to provide visitors with something compelling to look at.
We recorded a presentation of the system given to us as if we were typical visitors. The presentation explained all the 'what if' scenarios that could occur and how the system would adjust. And the explanation was based on a real section of the rail network that forced the system to operate in different modes depending on whether it was above ground or in the tunnel being built.
As we had already produced diagrams explaining how the high capacity signalling worked, we were able to speed up the process of understanding how the system worked and get straight to mapping out what it did. We mapped out the section of line that would use the new signalling and run the high capacity trains and built onto it all the scenarios in the presentation. This gave us the the basis for a schematic of the system.
Then we refined it over and over until it made sense to everyone and could be understood without explanation as well as be followed as an explanation was being made.
Then we had it printed and mounted to the walls of the software lab as well as other locations in the building for use by people working on the project. This last aspect of the project didn't surprise us as we know from experience that once a good schematic is created, extra audiences appear.