Trainsplit - Not offering cheapest split point

[MKB]

Out: 10:54, Sat 27 Nov, Nuneaton to Liverpool (change at Stafford)
Return: 17:47, Sat 27 Nov, Liverpool to Nuneaton (change at Stafford)

For a flexible ticket, Trainsplit always used to recommend splitting at Tamworth using two Off-Peak Day Return (CDR) tickets.
Now, it is recommending a slightly more expensive split at Stafford.

I can't for the life of me work out why Tamworth is no longer valid. What am I missing?

 

[Paul Kelly]

This will be because of compulsory reservations on the Avanti train. It's not feasible to check all split points because they must be checked against the reservations system. You could just select LNR services instead and simply use the CDRs on the Avanti train?

 

[MKB]

It's not that because both splits (Stafford or Tamworth) book on to the same trains, and none are yet "full".

 

[Paul Kelly]

I don't mean that the Avanti train is blocking the reservation, but rather that the journey planner must be pragmatic about how many split points it searches for if it involves making mandatory availability checks. For normal walk-up splits when no availability checks are needed (e.g if all services are LNR) it can do an exhaustive check.

 

[MKB]

Ah I see. Thanks for that. Does Trainsplit (Raileasy) get charged for doing availability checks, or is it simply that it adds too much time to the algorithm?

Obviously, I know the cheapest flexible ticket in this case is a split at Tamworth, but for other routes where I'm not sure, there doesn't seem to be a workaround to force an exhaustive search that doesn't do availability checks. In this case, I tried restricting to LM trains only, but then Trainsplit suggests LM-only fares, which is not what I want!

 

[Bletchleyite]

I don't mean that the Avanti train is blocking the reservation, but rather that the journey planner must be pragmatic about how many split points it searches for if it involves making mandatory availability checks. For normal walk-up splits when no availability checks are needed (e.g if all services are LNR) it can do an exhaustive check.

I guess that means for Advances it does fewer checks, as you need to do availability checks for those? Interesting.

 

[Watershed]

Ah I see. Thanks for that. Does Trainsplit (Raileasy) get charged for doing availability checks, or is it simply that it adds too much time to the algorithm?

There isn't a charge per se, but I imagine that would quickly change if every single possible split point were checked...

As you say it's also a question of how quickly you want your results - if you're going to check for 30 stations' worth of combinations and permutations of splits, waiting for reservation availability results to come in from a remote server is going to take some time...

 

[infobleep]

There isn't a charge per se, but I imagine that would quickly change if every single possible split point were checked...

As you say it's also a question of how quickly you want your results - if you're going to check for 30 stations' worth of combinations and permutations of splits, waiting for reservation availability results to come in from a remote server is going to take some time...

I wonder how long that would be? There us an intensive search option on Trainsplit but I have never found anything further after using it.

That's not to say it doesn't work, just not in my case.

 

[kieron]

As I see it, if I planned to travel with Avanti from Warrington to Glasgow using flexible tickets, I'd expect the retailer to check that one seat is available for me between Warrington and Glasgow. If one is available, I can use any valid ticket combination. If none are, I can't use that itinerary at all.

Does something require you to check the reservation system over and over again for a reservable train?

 

[SickyNicky]

There is different availability on different segments. Seats may be flagged as available for some origins and destinations, but not for others. So you have to check everything (sigh).

 

[Watershed]

There is different availability on different segments. Seats may be flagged as available for some origins and destinations, but not for others. So you have to check everything (sigh).

Indeed, for example Lumo services are marked as "reservation compulsory" for the next few weeks, and yet they do not issue reservations for journeys between Morpeth and Newcastle. That makes it impossible to book the cheap Lumo only fare online!

If journey planners only checked for reservations for the entire journey (let's say Newcastle-Edinburgh) they may well be misled into thinking that there is reservation availability.

 

[pelli]

If I understood correctly, for the OP's case, the claim is that the Trainsplit engine may have decided to only check availability for the Stafford split and not the Tamworth split in order to avoid excessive checking of availability. But the prices of walk-up tickets are known beforehand, so if only a limited number of checks are to be made, why not check the cheaper Tamworth split instead of the more expensive Stafford split?

In general, when a splitting engine faces the question of which order to check availability in, for walk-up tickets (when no advances are involved, or the user has selected the "flexible" option) it seems to me that (crudely ignoring the fact that different splits can require different numbers of availability checks) a good strategy is to just sort the different split options by increasing total price and check them in this order. This way you can stop checking as soon as you find availability (as you then know you've got the cheapest available option), and unless you have additional knowledge about which legs are likely to be available (be it through statistics or memory from previous checks) any other order will on average use the same number of checks before the first availability is found anyway.

 

[Watershed]

But the prices of walk-up tickets are known beforehand, so if only a limited number of checks are to be made, why not check the cheaper Tamworth split instead of the more expensive Stafford split?

For reservation compulsory services, I suspect Trainsplit only ever considers a limited number of split points; the possibility of splitting at Tamworth simply isn't considered and so the fact that the fare is cheaper when spitting there doesn't enter the 'equation'.

In 99% of cases this approach will still result in the cheapest fare being found, but obviously there are certain journeys such as this where it means that the cheapest fare is missed.

This is yet another of the unintended consequences of falsely marking services as "reservation compulsory".

 

[Haywain]

It should also be borne in mind that Trainsplit does not claim to find you the cheapest fares, but to save you money over through fares.

 

[miklcct]

Why do you need to have a seat for a flexible ticket? Aren't flexible tickets sold without regarding to seat availability? I believe that trains are designed in a way such that even if there are a few standees they are still safe to run anyway. I remember when buying direct from train companies, it reminds only select a service if you want to reserve a seat.

And what will happen if you take a reservation compulsory service but you are unable to book a seat because there is no availability?

 

[infobleep]

This might explain why in the recent past a split at Surbiton didn't show up on Trainsplit.

To be fair to Trainsplit, they got me a cheaper fare than the through price from Surbiton to my destination, so it was a helpful tool in addition to my work in locating Surbiton as a split point. And I purchased all the tickets from Surbiton through them, so they got some share of my split savings.

I like to think of it as a partnership. I check their site and if I wish to get a cheaper price, if, at all possible, I hunt around and then purchase through them if they get me a split saving.

If it's a walk-up ticket, with no split, usually I just use a TMV.