diamond geezer

 Monday, March 11, 2019

What happens to the balance on an Oyster card when you make a journey?

It's not this...
Touch in
Touch out
    [get charged for journey]
...because anyone who failed to touch out would travel for free.

It's this...
Touch in
    [maximum fare deducted]
Touch out
    [maximum fare refunded]
    [get charged for journey]
This way anyone who fails to touch out pays the maximum fare, and law-abiding folk pay the correct amount.

The maximum fare is £8.20 (equivalent to the peak fare between zone 1 and zone 6 if using a combination of TfL and non-TfL services). Almost all journeys within London are cheaper than this, but the system punishes miscreants by assuming they made the most expensive one.

n.b. The maximum fare is not always £8.20.
» If your Oyster has a discount applied, the maximum fare is £5.60
» If you have a season ticket and use it outside its zonal availability, the maximum fare is either £5.90 or £4.60 (because your season ticket covers some of the full £8.20 journey)
» If you travel on TfL Rail to/from Heathrow without touching in/out the maximum fare is £10.10 off-peak or £10.50 peak
» If you travel on Heathrow Express without touching in/out the maximum fare is £22 off-peak or £25 peak
» If using Oyster at a National Rail station outside Greater London the maximum fare may be more, for example at peak times £8.30 (Broxbourne, Hertford East, Ware, St Margarets, Rye House), £8.40 (Chafford Hundred, Grays, Ockenden, Purfleet), £9.00 (Epsom), £9.60 (Shenfield, Watford Junction) or £15.10 (Gatwick Airport)
But let's pretend it's always £8.20, because that'll make what follows easier.


After you touch in, your Oyster card contains £8.20 less than it did beforehand. It continues to contain £8.20 less throughout your journey. Only when you touch out do TfL reimburse you the difference between the actual fare and the maximum fare, ensuring everything balances out.
Touch in
    [maximum fare deducted]
Touch out
    [difference between maximum fare and actual fare refunded]
For example, if travelling from Leicester Square to Covent Garden in Zone 1, suppose you start with £3 on your Oyster card. On touching in £8.20 is deducted, leaving a negative balance of -£5.20 during travel. On touching out that £8.20 is refunded and the actual fare of £2.40 is taken, leaving you with 60p on your card.

This is not new.

What's new is whether the ticket barriers open or not.
Touch in
    [check PAYG balance]
    [open ticket barriers]
    [maximum fare deducted]
Touch out
    [difference between maximum fare and actual fare refunded]
    [check PAYG balance]
    [open ticket barriers]
If you don't have enough Pay As You Go on your Oyster at the start of your journey, the gates won't open. This is the dreaded error 36 ("Insufficient PAYG").

You don't need to have £8.20 on your Oyster for the gates to open. Instead your balance only needs to exceed the Entry Threshold, which is the minimum PAYG fare from that station.

The minimum PAYG fare at a Zone 1 station is £2.40, which means the gates will open so long as you have at least £2.40 on your card. At stations in zones 2-6 the minimum PAYG fare depends on time of day - £1.70 peak or £1.50 off-peak. TfL always assume you're about to make the cheapest possible journey, and if you have enough PAYG for that then the gates will open.
Touch in
    [if Entry Threshold exceeded, open ticket barriers]
    [Entry Charge deducted]
Touch out
    [Exit Charge refunded]
    [if Exit Threshold exceeded, open ticket barriers]
For example, if travelling from Leicester Square to Covent Garden in Zone 1, suppose you start with only £2 on your Oyster card. That's too low to qualify as a cheapest possible journey so the gates won't open and you'll have to top-up before travelling.

This is not new either. What's new is how the Exit Threshold is applied.

Assuming you touched in, the gates will always open when you touch out.

For example, if travelling in the rush hour from Uxbridge in zone 6 to Covent Garden in Zone 1, suppose you start with only £2 on your Oyster card. That's enough to qualify as a cheapest possible journey from Uxbridge, so the gates there let you in. It's not enough to pay the fare to Covent Garden, which is £5.10, but the gates still let you out with a negative balance of -£3.10.

But if you didn't touch in, then the Exit Threshold comes into play. This is TfL's way of deciding whether or not there's enough money on your card to open the gates and let you out.

If your balance exceeds the Exit Threshold then a maximum fare is applied and you pass through. If not then Error 36 flashes up and a member of staff is supposed to come over and guide you towards the ticket machine to pay manually.

Previously the Exit Threshold was the same as the Entry Threshold - the fare for the cheapest possible journey to that station. That's at least £1.50, and in zone 1 as much as £2.40.

For example, if heading to Covent Garden suppose you thought you'd touched in but you hadn't, and there was only £2 on your card because you hadn't topped up lately. It happens. Covent Garden's Exit Threshold is £2.40, so Error 36 would have trapped you on the wrong side of the gates, still with £2 on your card, requiring a member of staff to let you out.

Error 36 causes hassle, particularly at busy stations. First the blocked gate slows down passenger flow, then the subsequent rigmarole occupies staff. In an age of automation it's not ideal.

So what TfL did last month is tweak the Exit Threshold so that it's no longer identical to the Entry Threshold. It used to be positive and now it's negative. It's now -£2.00.

In other words, for those who fail to touch in, ticket gates at TfL stations will now let you exit so long as you're not in deficit by more than £2. That's real money at the end of the trip, not all this faffing around with maximum fares mid-journey. Even if your Oyster balance started out low, the gates will likely open.

For example, if travelling from Uxbridge to Covent Garden, suppose you start with £2 on your card but somehow fail to touch in. The cheapest possible journey to Covent Garden would have cost £2.40, leaving a balance of -40p. Previously this would have triggered Error 36, but -40p is above the new -£2 threshold, so now the gates let you out. Importantly the system doesn't charge you £2.40 but the maximum fare of £8.20, so your final balance is -£6.20.

Nobody's getting away with anything here. If Error 36 doesn't get you then a maximum fare will, and any card ending up with a negative PAYG balance always needs to be topped up before it can be used again.
Touch in
    [if card balance exceeds fare for minimum possible journey, open ticket barriers]
Touch out
    [if customer touched in, open ticket barriers]
    [if card balance exceeds -£2, open ticket barriers]
    [if neither of the above, Error 36]
Since the change to the Exit Threshold was introduced TfL's ticketing team have noted that Error 36 is being seen at barriers 70% less often than before. That means smoother passenger flow and less need for staff to interfere when gates fail to open. They also haven't seen a significant increase in fraudulent usage. So all's good.

n.b. Customers using contactless payment cards are not charged an entry fare when they touch in to start a journey. All fares are charged at the end of the traffic day. However, they can still be charged a maximum fare if they don’t touch in at the start of their journey or out at the end.

But how complicated all this is, and that's just for an individual journey. When it comes to combinations and capping even fewer customers understand why they're being charged what they're being charged, they simply swipe and go. Fares for train travel in London have become increasingly opaque, calculated within a 'magic box' and paid on trust.

You can read the official explanation of this gate reader change on pages 12 and 13 of the latest edition of Ticketing & Revenue Update, the bimonthly publication for all Station and Revenue Control staff. TfL would rather not publish these, but Freedom of Information requests force their hand and redacted versions are regularly released. In edition #115 you can also read about what went wrong with the POMs at Moorgate, what happened yesterday regarding platform tickets and an explanation for the Epsom Freedom Pass debacle.

I wouldn't be surprised if I've got certain bits of today's post wrong, or made incorrect assumptions, so do let me know if anything's amiss. You usually do anyway.


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