If designing new, I'd suggest each display has an LED adjacent to it, coloured (e.g.) Green (or maybe unlit) if the seat is Unreserved, Yellow if it is reserved later in the journey, and Red if it's reserved from this, or a previous, stop. In doing so, we've replicated, and improved on, the main functionality of paper tickets. The displays should be of sufficient size to display information without scrolling.
Of course, I've entered fantasy land. However, under the constraints of the current displays, it's clear a lot more thought could be put in to it. If you have scrolling text, every letter counts. I'd suggest carefully thinking about the exact phrasing, abbreviation station names as appropriate (reservations until Bristol Parkway and/or Bristol TM‡ might be better displayed as just Bristol, for example). And the apparent switch to just displaying "Reserved Later" is demonstrably silly.
This is what is in the
IEP▸ specification:
TS640 The automatic seat reservation system must deliver the following functionality: - interface directly with the Relevant Operator^s seat reservation system (which shall be assumed to be the same as the national seat reservation system). The reservation system shall utilise this data to maintain the reservation database for each IEP Train;
- automatic remote download of reservation data via a communications link immediately prior to the start of a timetabled journey within a maximum of 5 minutes after the service to be operated has been confirmed to the IEP Train;
- allow on board train crew to load or update seat reservation data for that IEP Train;
- displays for each seat must indicate whether that seat is free, reserved for part of or for the remainder of the journey. The method of display must be easy for passengers to interpret quickly when boarding, and shall seek to convey an overall impression of
the extent of reserved and unreserved seats within the saloon; and - displays must be automatically updated throughout a journey to indicate the current reservation status for the remainder of the journey.
Presumably that represents what the
TOCs▸ and
DfT» think ought to be provided.
It does not look to me quite like the results of modern system design practice, meaning that you start by describing who uses it, what for, and what they are doing. If I try that, I get:
Passengers with reserved seats: strictly they need nothing, other than to easily find their carriage (displays inside and out required for IEP) and seat (no requirement for numbering!). Since we all know it needs to show "reserved" for other reasons, these passengers need it to do so too. Also, if there is a dispute, they need something to point to (see below).
Passengers without reservations: need to easily pick out seats free now, and if possible for their journey. Without reservations during the journey, the minimum is "free until x" or "reserved". Having "reserved until y" is better if you may have to stand and wait for a seat.
If you add reserving seats during the journey, that possibility could be indicated by static signs or the display. However, if there are unreservable seats, they need to be indicated.
If there is any dispute, both passengers and train staff need what has already been defined. If extra information can be provided, e.g. origin and time of reservation, that may help staff in particular sort out who is right, but also to spot system errors or the results of abuse of the system. A case can be made for such extra information to be provided only to staff.
Note that I agree the wording needs come care - the TOCs might not like "free", but labels including "reserved" plus qualifications do get rather long, and there are few good alternatives.
In addition to spec. item 4 in TS640 above, there is more help on offer to find free seats. The IEP specification also includes a passenger counting capability, which surprises me - I had no idea that is now reliable enough to support this feature:
TS1931 The PIS▸ must utilise the data from the passenger counting system to indicate to passengers within the IEP Train the status of the occupancy of each IEP Vehicle. It occurs to me that passengers would find life a lot easier if most trains used their displays in the same way. That could emerge from the national ticketing setup, though that looks unlikely at the moment. It should not be difficult to alter trains already in service, since this is "only software".
(PIS = Passenger Information System)