A colleague at IDC, asked me, "Mandar, did you notice the colors in the (Mumbai) Metro symbol, are they meant to be line colors for the Metro in the future?

Design for people / June 9th, 2015 / Research Associate: Hriday Gami

I said, I don't know, but I knew it raised an important concern…

Installed maps at Ghatkopar Metro station. In order to prioritize the Metro route, the map is rotated. This rotation makes the North direction to point towards the left (ideally should point to the top). Photo shot on June 9, 2014. 
The Metro in Mumbai currently runs a single line on the Ghatkopar-Versova corridor. Since we aspire to make the Metro meet international standards, maps have become a default at stations. It is a part of the station layout. The line in operation is depicted 'Red' on the maps and 'Blue' on their website and inside the train. Therefore, the colour for the line can be defined as 'Red' or 'Blue'. Currently it does seem like a problem, as only one line is operational, but what about the future?
The Mumbai Metro line is 'Blue' on their official website and the upcoming line is depicted 'Red' . Date of reference 13 Nov 2017. Source: http://mumbai-metro.com/mumbai-metro-map/
Mumbai metro plans to construct a network of 10 metro lines. When more lines become operational, the designer of map and wayshowing systems will need to 'color code' these lines to aid commuters navigate. It is quite likely that designers at the Metro ignore the color coding in the Mumbai Rail Map (MRM) and choose their own set of colors. These colors, if chosen randomly will act as constraints for other lines [Central (CR), Western (WR), Harbour (HR) and Monorail] as they would be forced to follow/ or not follow the colors fixed by the Metro designers. The other lines (CR, WR, HR) will have to manage by choosing a different hue (not RED) to avoid conflict with the line of the Mumbai Metro. 
As a consequence, the overall color palette, which is color-blind friendly in the current Mumbai Rail Map (MRM), will have to be changed as per the decisions of each rail network. If each rail network thinks of itself as an individual entity and takes independent decisions for color coding lines, we will all struggle to achieve a single, harmonious, easy to understand, user-friendly and inclusive rail route map for the city.

Design of the current station name board: Kings Circle

kings circle station board
King's Circle is a railway station on the Harbour line of the Mumbai Suburban Railway network. Current design of the station names board uses two semi circles in red colour and similar treatment is found at all stations on other lines - Shot on 15th June 2015
Although all network lines should have a line code and colour, let’s restrict this discussion to suggesting how we may incorporate the line colours from the map into the existing station name boards considering the current constraints and cost implications. Presently, the station name boards have a semicircle (currently in red colour) that can be painted according to the rail line color to indicate the line to which the station belongs. It’s a crucial clue at junction stations, like Dadar, Kurla, where two or more lines meet. 

Proposed: Implementation of line colors in the map to the train station boards of their respective lines

If implemented, over a period of time people/children will learn the coding and just by glancing at the signboard and they’ll be able to identify/relate the line they’re on. It's a visual solution and with repeated encounters it can become a visual language. It’ll help novice commuters orient themselves in their journey and reduce anxiety. Map line colors and the station board name colors should compliment each other and should be applied as conscious design decisions.
Proposed Line colours scheme for Western, Central and Harbour Rail in alignment with MRM line colors
Proposed Line colours scheme for Trans Harbour, Metro and Mono Rail with in alignment with MRM line colors

While designing public information systems if colour is for a reason, it helps. For the newly designed station name boards. there is change in shape, but colour has no function.

Design for people / November 12, 2017
Newly designed station name board at Bandra Station (western railway). Shot by Shivani Nayak, IDC student - Communication Design

Station name board in Japan, displays the previous and following station names, the line colour and direction of travel. 

Station name board in Japan. If designed properly there is lot we can do with a station name board. 

The rail map is only one of the components that aid navigation. In order to arrive at a holistic solution, we must address the rail information eco-system in totality.