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Old 13th August 2012, 17:06   #7
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1.3 Advance quotas

It is well known that advance fares are quota-controlled, based on the reservations system, and that it is important to book as soon as possible after reservations open to get the cheapest fares. Much less widely understood is the system by which advance quotas are enforced. It is often thought that a fixed quota of advances at each price tier exists between every pair of origin and destination stations, but in reality the quota mechanism is more complicated than that.

The journey made by each train on which advance fares are offered is divided into segments, corresponding to the calling points of the train. For example, a train from Edinburgh to London King's Cross might have 4 segments:
  1. Edinburgh to Newcastle
  2. Newcastle to York
  3. York to Peterborough
  4. Peterborough to London
For a through Edinburgh to London advance fare at a particular price tier to be available on this train, quota for that price tier must be available on every segment of the journey. If even just one segment has run out of quota for that tier, an advance for the through journey at that tier cannot be offered. Instead, booking engines will offer the lowest-priced advance tier for which quota is available for every segment of the journey.

So it is possible that if a lot of people were travelling between Newcastle and York one day, they could "use up" all the cheapest quota on that segment of the journey. This would affect more than just passengers travelling between Newcastle and York, but anyone who would potentially be travelling on that journey segment. E.g. the cheapest advances from Edinburgh to King's Cross would no longer be available either, even if there was still cheap quota available for the Edinburgh to Newcastle, York to Peterborough, and Peterborough to London segments.

The result of this is a "weakest link" effect: cheap advances are only available for a through journey, if every single journey segment has cheap quota available - and if not, only a higher priced advance for the through journey can be sold.

It is common for the cheapest quota for the journey leg closest to a major centre of population to get used up very quickly, resulting in only expensive advances being available for much longer journeys that include this "weakest link segment" at either end. A good example of this is a journey from Cambridge to Birmingham on CrossCountry. Advances between Leicester and Birmingham are very popular, and quota for the cheapest tier gets used up quickly - often while journey segments east of Leicester still have plenty of cheap quota available. In this situation it can offer quite a saving to buy a cheaper-tier advance from Cambridge to Leicester, and combine this with a higher-tier advance or off-peak day single for the final journey segment between Leicester and Birmingham, resulting in a significant saving over the higher-tier advance price for the through journey from Cambridge.

1.3.1 Barred Journeys
The quota mechanism explained so far covers a lot of the unusual phenomena seen with regard to advance fare availability. However there are some more tricks the train companies have up their sleeves, to reduce advance availability even when there is still theoretically quota available.

These mechanisms are known as barred journeys and involve either blocking, or putting a reduced quota on, journeys that start and/or end at a particular station. This is usually done purely for the purposes of increased revenue generation, rather than controlling demand on services.

For example, East Coast have competition with Virgin West Coast for through journeys from London to Edinburgh. Virgin often have a lot of spare capacity on their trains, and offer cheap advances from London Euston to Edinburgh via the West Coast mainline to attempt to fill this. East Coast need to compete with this, so offer a full range of cheap, low-tier advances from London King's Cross to Edinburgh.

On the other hand, from York to Edinburgh East Coast's main competition is with CrossCountry. Their trains tend to be overcrowded and they don't offer so many cheap advances, so East Coast have no need to compete so much. To make the most of this situation, they may put a block on quota at the cheapest tiers being used for York to Edinburgh journeys. Passengers trying to book from York to Edinburgh may therefore be faced with only higher tier advances available, even though there is still cheap advance quota available on that train - and it may be booked by passengers making through journeys from Edinburgh to London.

Unfortunately, even though a ticket from Edinburgh to London may be cheaper than one from Edinburgh to York, since advance fares do not permit break of journey there is no easy way to get around this competition-based pricing.
1.3.2 Seat Reservations and Quotas - Further Quirks
In order to explain a few further quirks in relation to booking advance fares, it is necessary to briefly summarise the mechanism by which quotas are enforced. Booking systems enforce advance quotas by attempting to make a seat reservation on the relevant train(s). This is done in a very straightforward way:
  • For each train in the journey itinerary, the booking system first asks "Is it possible to make seat reservations on this train?" (this information is stored as part of the timetable)
  • If yes, the booking system then connects to the National Reservation System, and for each advance price tier (i.e. ticket type) in turn, starting with the cheapest, it asks "May I book a seat for these journey segments with this ticket type?"
  • If the given train has quota available for that ticket type (i.e. price tier) for every journey segment, then the seat reservation succeeds, and the advance fare has been successfully booked at the cheapest possible tier.
The fact that booking advance fares is so intrinsically tied to making a seat reservation leads to a number of complications, which are discussed below. Booking for large groups

This is a limitation of most booking systems, rather than the reservation system itself, but when booking a journey for, say, 2 people, but there is only one seat left at a given price tier, a reservation will usually be made for two seats at the more expensive tier, rather than one seat at the cheaper tier and one seat at the more expensive tier.

Current booking systems are not intelligent enough to try booking seats singly; if there is not enough quota left at a given tier to book the total number of seats requested, the booking system will only offer fares priced at the first tier that has enough quota available for everyone. "& CONNECTIONS" advances and connecting services

Most long-distance train companies offer advance fares for journeys where the majority of travelling is done on their service, but there is a relatively short connecting journey on a local train company at one or both ends of the journey. This is known as an & Connections advance.

Complications arise with this type of ticket when the connecting service also permits seat reservations to be made. The booking engines do not generally have the intelligence to know which is the "main" service and which is the "connecting" service. Thus if a connecting service also offers seat reservations, the booking engine must attempt to make a reservation on this train, in order to be sure that the advance fare is not quota-controlled on this train (this is generally quite rare for connecting services, although long-distance inter-city TOCs may put a zero quota on each others' advances, e.g. to avoid "XC & CONNECTIONS" advances being used on a Virgin service, for example).

This has two main undesirable side effects:
  • The passenger receives a reservation for the connecting service in addition to the main service, which binds them to using that specific connecting service (according to the terms & conditions of advance fares) and means they may not have a chance to use station facilities at the connecting station. It also means they are not permitted to start the connecting journey a little earlier, in order to be sure of making the connection to the main service.
  • A booking cannot be made for a through journey until reservations have opened for both the main and connecting services. As mentioned above, the booking engines do not have the intelligence to know that there will be no quota enforced on the connecting services, and so they must wait for reservations to open if the connecting service is marked in the timetable as reservable. This delay can result in the cheapest tier of advances being already used up by the time it is actually possible to book the ticket!

By using a little ingenuity it is sometimes possible, depending on the route involved, to avoid being given a reservation for a connecting train by adding a suitable 'via' station to the journey planner in a booking website. This via station should be a station that no reservable connecting services call it, but that non-reservable connecting services do call at. It must also not be a timing point for any reservable services, as information on timing points is also available to the booking websites. ( will show details of all the timing points in a train's schedule if required.) Counted Place Reservations

Some train companies have started to offer advances on services that traditionally did not have seat reservations available. To achieve this they mark the service in the timetable as having reservations available, but then issue reservations marked "Coach *, Seat ***", i.e. a reservation for the train, but without a specific seat. This is known as a Counted Place Reservation.

This does not cause any difficulties in itself, but with more and more services being marked as reservable for advance fares, it increases the likelihood of being issued with an unnecessarily binding reservation for the connecting portion of a journey on an & Connections advance, as discussed above. For example, this is a particularly common problem when travelling into London Waterloo with South West Trains on the connecting leg of an advance to the north of England; many SWT services have SWT-specific advances available, and so appear to the booking system as reservable.

The other reason why a "Coach *, Seat ***" counted place reservation might be issued is that some train companies do not wish passengers travelling on Advance tickets to be given a seat reservation, preferring to try and restrict availability of seat reservations to passengers travelling on Anytime and Off-Peak tickets. This is particularly common on Arriva Trains Wales services. If a "proper" reservation is desired for travel on such a service, it is usually possible to obtain it by buying the Advance ticket at a rail station booking office, rather than through a web site. Changing Seat Reservation

This issue is specific to East Coast trains and is due to a limitation in the booking system used on their website rather than an inherent problem with the advance quota/reservation system, but as it has caught a number of people out it is worth documenting.

To secure availability of an advance fare, the booking system will make a seat reservation (and assign a random seat; the important thing is that quota was available). The system then offers you the opportunity to change your seat, and when a new seat is selected it attempts to make a new seat reservation before releasing the old one. A problem arises if you had booked the last seat available at that advance price tier though; since it can't make any more reservations at this tier it refuses to change the seat.

Last edited by Indigo2; 13th January 2013 at 10:57.
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