The brief would contain either themes or slogans that would need to be illustrated photographically. I would also plan to create simple mock-ups of the concepts - I have limited design skills so this would be quite basic. An example might be the following:
I need some time to think about this more before starting on any photography, however, I spent some time today with Heidi brainstorming the concept. We have both worked in marketing so this is not new to us, although the subject matter is.
1. Words - that might be associated with the network
2. Themes - around which I could build a portfolio of images
Food and Shopping
Above ground, where the line takes you
3. First Slogans
On the Move
Go the Distance
Colour your Journey
Guide Your Visit
Photographically this offers many opportunities, the network is very diverse and often colourful. I can image the people, the rolling stock, and the architecture above and below ground. The downside is that I suspect this is probably illegal, but the risk is low that I would encounter serious trouble. There is no signposting and tourists take a lot of photographs in the system.
I have been thinking about this for some time and even acquired a small book providing a guide to the network to use as a visual reference