Home > Sean's Technology and Writing Blog

Time to check the Oyster source code...

29 January 2008

So, they've built this massive infrastructure for electronic payments on the tube. When you think of the scale of the thing, it's amazing. It works at every station on the tube network and you can charge up cards at stations or online. You can even charge up your cards in newsagents. The system debits your journey price from the card balance, and shows you how much credit is left when you leave the station.

I've just registered for automatic top-up. That means that when my balance gets below £5, they'll charge my credit card £20 and credit it to my Oyster card. Clearly, I need to have a lot of trust in them to grant them this authority. Firstly, that they're counting the cost correctly, and secondly that they won't mischarge or overcharge me.

So, what's my first experience with autocharging? Receiving the following email (I've made no edits to this):

You have successfully uploaded Auto top-up from <PickupStationName> station on your Oyster card, number <OysterCardNumber> and topped up your pay as you go. Auto top-up is now active on your card.<br><br>Whenever you travel on the Tube, DLR, Tram or Bus GBP<AutoloadTopupAmount> will automatically be added to your Oyster card at any station, using your credit or debit card ending in <HashedCCNumber>, when you enter a station and your pay as you go balance is below GBP5.00. You can change your Auto top-up arrangements at www.tfl.gov.uk/oyster.

This tells me that nobody has ever tested this system end-to-end, otherwise they would spot that the email merge isn't working. That doesn't exactly inspire confidence.

Permanent link for this post | Blog Home | Website Home | Email feedback

Dip into the blog archive

Credits

Visit www.sean.co.uk for free chapters from Sean's coding books (including Mission Python, Scratch Programming in Easy Steps and Coder Academy) and more!

Discover my latest books

100 Top Tips: Microsoft Excel

Power up your Microsoft Excel skills with this powerful pocket-sized book of tips that will save you time and help you learn more from your spreadsheets.

Scratch Programming IES

This book, now fully updated for Scratch 3, will take you from the basics of the Scratch language into the depths of its more advanced features. A great way to start programming.

Mission Python

Code a space adventure game in this Python programming book published by No Starch Press.

Cool Scratch Projects in Easy Steps

Discover how to make 3D games, create mazes, build a drum machine, make a game with cartoon animals and more!

Raspberry Pi For Dummies

Set up your Raspberry Pi, then learn how to use the Linux command line, Scratch, Python, Sonic Pi, Minecraft and electronics projects with it.

Earworm

In this entertaining techno-thriller, Sean McManus takes a slice through the music industry: from the boardroom to the stage; from the studio to the record fair.