Putting aside the system being activated mid-journey, there remains the problem of people taking time to search / read all the labels, and having good geographic knowledge to then interpret them. A tourist joining at Paddington and travelling to Oxford may not understand whether a seat reserved from Reading to Evesham is available for him.
How about an app linked to your e-ticket - hold up your phone and the light colour on the reservation system can show red (reserved for your journey), yellow (reserved for part of your journey) and green (available throughout your journey. A mark 2 version which attached to sensors in seats will turn green seats to orange if a seat is fully occupied and to blue if a seat has a lighter weight (such as luggage or a child under 5) occupying it.
I appreciate I'm looking a long way ahead - perhaps so far ahead it's fantasy. But holding up you phone and - in the same time that a ticket barrier takes - giving you a display of seats that will work for you - seems an admirable way forward.
I see a few problems with this:
1. Not everybody has a smart phone, and especially not tourists from other countries who have packages (like me) where international non-
EU» roaming charges are prohibitive if not penal. When I am in South Africa, for example. my lot want £3 per mb (yes that is not a typo - £3 per mb) when I can buy a 2 gig package locally for under £20.
2. There is already (or there is when the seat reservation system works properly) a traffic-light system just as you describe on the 800s. I honestly suspect that this covers the vast majority of reserved seats on the
GWR▸ network at least. Other
TOCs▸ will differ, of course.
On the matter of seat reservations in general, I suspect I could rattle on about it more than broadgage rattles on about buffets, but in my view the current system is a joke anyway. Seat reservations are being issued like confetti, resulting in many reserved seats not having their intended occupants in them through not being on the train for one reason or another, or sitting somewhere else when they are on it. Some people take no notice of them (like me - I tend to park by backside in any seat I like the look of and only move if someone comes along with the reservation - and I don't get asked to move very often) to others who treat it like an airline-style reservation.
I witnessed one incident a fortnight ago on a 75% empty off-peak Liverpool St to Norwich, where somebody came along and "claimed" a reserved seat from someone sitting in it (table seat by the way) when there were twice as many unreserved seats in that coach than reserved ones, and table seats to boot). When the reverse happened to me in the days when
HSTs▸ were dragging around two and half coaches of first class
ECS▸ for most of the day and first class advance tickets were virtually being given away, I just sat somewhere else rather than churlishly asking the bloke sitting in "my" seat to clear off.
On busy services (and I am thinking especially of Bath in the evening peak when the
IETs▸ are full of commuters going one or two stops and tourists going back to London) it can cause havoc with loading as people with luggage bugger about trying to find "their" seat, potentially asking others to move, whilst at the same time blocking the aisle and preventing people on the platform from getting on the train.
What can actually be done about it is debatable, but something needs to be done.