State-of-the-art analysis

Meatspace metro signage.

The non-digital information present in the metro, specifically static or machine-generatable information. I have divided this into five categories:

Information about gaining access to the metro.

• Street-level:
• Street signs, T-symbols, sometimes metro line colour.
• At entrance points:
• How to pay for and use tickets or passes.

The pass vending machines, turnstiles, toll booth, as well as the passageways and stairs, are recognizable and well understood symbols by themselves. Much signage is not needed for where they are or their context of use.

The toll booth, when staffed, is of course potentially a near endless source of information. In fact any human present—employed by the metro or not—has that potential, but such sources are outside of the scope of this analysis.

Information about using the metro.

• System/station maps at the entrances, platforms and inside the trains.
• Station names and exit guides at the platforms, somewhat visible from inside the trains.
• Also signs about platform inter-connectivity.

The platforms, safety lines drawn on platform edges, benches, rubbish bins (and often clock) are—as above—of well understood purpose.

Dynamic information about metro events.

• Displays show:
• Wait time for upcoming train. Sometimes scrolls wait times for several.
• Destination/end-station for upcoming train(s).
• If the arriving train has few wagons/is short.
• Ad-hoc information, typically about delays.
• Speaker on platforms informs about delays and other ad-hoc messages.
• Speaker in trains informs about station stops and ad-hoc messages.

The trains are very visible, and they are—including their doors and seats—of well understood purpose.

The information in the display is sometimes animated/scrolling, which during a long wait on an empty station is the only thing that confirms the passing of time.

Safety and regulation, e.g. notes about "keeping off the rails".

Advertisements.

• Large billboards facing the platforms (some stations).
• Medium billboards on the platforms (some stations).
• Ad-space along the top of the windows inside the trains.
• On vending machines (some stations).

In some stations the advertisements are given more area than all the rest of the signage put together. The advertisements are also typically the most attention-grabbing. It's also the only information that is not there to help the travellers in using the metro. This brings into question the non-functional requirements of the metro.

If revenue (on top of government subsidies and ticket fee) is sought, then more ads could easily be played over the speaker systems on platforms and in trains, and ads could be interspersed in the scrolling display about upcoming trains. It would also be easy to install screens (with sound) in the trains that show tv-ads, as is done in some other countries. Of course the average user would balk at such changes, claiming it to be too intrusive, but after a few years it would become the new normal.

On the other hand, if revenue for the metro was not the goal of the service, then these spaces could be used for something that benefits the travellers: practical information and/or art.

Non-functional requirements for metro signage.

The metro is a core component of city infrastructure, therefore the signage should be:

• Reliable 
• Must never give wrong information about critical information such as delays.
• For sub-critical information it should at least be accurate enough to gain users' trust. 
• Tamper proof/unexploitable 
• For the above reasons. 
• Sturdy 
• For the above reasons since the metro can be a harsh environment. 
• Maintainable 
• Specifically day-to-day maintenance should be limited to cleaning (see Sturdy), and repairs should be quick/modular. 
• Accessible 
• Must be usable/understandable by an extremely wide audience, including disabled, tourists, and disabled tourists. 
• Unobtrusive 
• Users should be free to their own agency to make productive use of their time on the platform and in trains.
• Unless ads are a functional requirement.