Sunday, March 22, 2009

Water, heat and short-term tickets

A byproduct of non-reloadable tickets such as Metcards or Myki paper tickets is littering. While it's true that the old paper tickets can be dropped, they seemed less noticeable on the ground than their substitutes.

The silver lining of this was the easy availability of used tickets to do further inspection and testing.


Dropping the card into a bowl of hot water revealed its layer sandwich construction. The first layer to come off was the paper back of the card. This made the card thin enough to see the insides when held up to the sun.

A further dunk allowed the blue front to be peeled off. This left only the middle two layers of the sandwich. In between these layers is the electronics. This comprises a multi-turn antenna around the edge of the card and the square RF ID chip (4mm x 4mm) in the centre of the card. Also readable is the card's brand (Confidex - a Finnish company) and a serial or batch number starting with 'HA'.

It is not known if the card has survived the dunking or not. However even if it did the ticket would not be valid.


Next it was time for a heat test. An iron made the back go black very quickly. This is not unlike a Metcard, which also discolours with heat.

An hour on a car's parcel shelf in direct sunlight failed to discolour the ticket. However it was not a very hot day and it would be worthwhile to repeat the test when the car's inside is 40-50 degrees.

Again it is not known whether this would have damaged the ticket or not.


Tristan said...

The reason they go black with heat is probably because that's exactly how the printers in the validators work: It applies heat, and that makes them go black. That way, you don't need to replace ink in the validator.

Peter Parker said...

Thanks Tristan, you raise an interesting point.

Though these tickets aren't printed when issued (a disadvantage compared to Metcards and paper tickets IMHO) it appears as if they've been designed to be printable given the right issuing hardware.

Daniel said...

Interesting post. Leaves me wondering if they're fully biodegradable.

Sam said...

Thanks for the series of posts on the myki system Peter; very interesting for someone who hasn't had the chance to get out to Geelong yet.

Daniel - I doubt they're biodegradable, but given that there will be a more convenient and easier way to pay for public transport (i.e. myki, if it works seamlessly) it should reduce the amount of metcard litter from today's standards, which is something I guess.