Hacker News Reader

Comment by hgomersall | Hacker News Reader

I don't think the suggestion is the QR code contains the ticket info, but that the QR code is the unique tag into the back end virtual ticket system. 1 to 3 are not relevant in that context, and 4 isn't borne out in my experience with modern readers (they're used in the bar code mix at parkrun and they read time is vanishingly fast with a smart phone, generally better than barcodes). The number of bits might increase the difficulty if capturing the code, but I would very surprised if a fast, robust system can't be built.

The huge disadvantage of NFC in this context is the electronic waste necessarily produced.

View on HN

The problem with expecting a "unique tag into the back end" is that these systems have to work offline.

The QR codes are significantly slower to read than NFC.

I've built both NFC and QR (and ye olde fashioned magnetic stripe) ticketing systems.

NFC doesn't necessarily create any additional e-waste. In Chicago we have an NFC system, and people typically just link their phone to their account and use that to pay.

I still use a physical card - so that I have a backup option in case something happens to my phone - but even there the volume of waste is trivial. I've had my current transit card for ages, and it doesn't expire until 2037. It's possible that the only technological decision I've made that generated less e-waste was deciding to splurge on a mechanical watch instead of a quartz model.

Well, yes, but the article is about a disposable nfc ticket.

Those are more for single rides by people who rarely or never use the transit system. I've had the same Carte Opus for years and just bring it with me and refill whenever I visit Montreal. And the disposable paper cards are being phased out. I'm not sure when the rollout will be, but Montreal is currently working on upgrading the system to allow people to just tap-to-pay at the turnstiles using their phones or compatible credit and debit cards.

Which is not something that you could do with a QR system. I don't know that anything is inherently wrong with QR codes, but they do seem to be a choice that's more appropriate for countries like China where the existing electronic payment infrastructure uses QR codes. In North America, by contrast, things have generally settled on NFC, and I think that that reason alone probably makes NFC the better option for North American transit systems.

> Montreal is currently working on upgrading the system to allow people to just tap-to-pay at the turnstiles using their phones or compatible credit and debit cards. > Which is not something that you could do with a QR system

I've got several apps that display QR codes on the screen for an external reader. One of them is for my health insurance id card (a simple 10 digit number), another shows my COVID vaccination status (this one is complicated, and I'm not sure why they used a QR code for it. It must include batch identification and other information given the size)

By tap-to-pay, I mean you need no special apps, you need no special accounts, any of that. You can pay with any physical credit or debit card that supports tap-to-pay, or you can use any credit or debit card you have loaded into your phone.

With a QR code like that, people still need to install an app, set up an account, etc. It's just a lot more friction. In cities where I can tap-to-pay, getting set up to ride a bus or train for the first time takes literally zero time; I'm already set up. If I need anything special - apps, accounts, system-specific QR codes, etc - then the setup time instantly goes up to a minimum of 10 minutes. It's a relatively large barrier to entry for infrequent riders, and ultimately serves to discourage use of public transit.

Really? Setting up contactless payment is quicker than having a QR code image? I use QR codes on the UK train system and I don't have any special apps. It seems to integrate with Google wallet too, which surprised me.

On rail systems with gates, these disposable "ultralite" RFID tickets are usually put through the old slot that used to take magentic tickets.

Exit gates usually capture the ticket on exit when it has been used up (ie single journeys, or after the number of trips encoded on the ticket).

These can (and are) recycled numerous times.

The point of the disposables is that they use the same technology (NFC/RFID) as the more robust long term multi-use NFC cards.

So if you're replacing an existing magnetic system, you can reuse the magnetic transports (belts/motors etc) for single use, including capture-at-exit and recycling for single journeys, while also adopting the NFC for multiple use.

> and 4 isn't borne out in my experience

To bolster your point, aren't there whole countries where stores and street sales float on top of QR codes?

In China, QR Codes are used for public transport too, and I found them just as fast as NFC readers (and faster than the slow readers used by the NS in The Netherlands)

Until you go to another city and discover that the local bus company has decided that instead of just letting you pay by Wechat pay or Alipay, you need to install their proprietary app to generate the QR code for the bus to scan, at which point the app then just turns it into a Wechat pay or Alipay transaction at the end. No benefit to the user, it just allows the bus company to extract all your PII in the process. Actually, they're not all proprietary apps, but there are several from competing companies, and you have to use whichever one the city has chosen.

Actually, I think part of the reason is that so they know who's on the bus in case it's involved in an accident, because if you buy a ticket from a bus station for a "short distance" (so out of the city, but within about 40km), you also have to provide them with a phone number even though they never call you or send you an SMS using that number.

>Actually, I think part of the reason is that so they know who's on the bus in case it's involved in an accident

The CCP certainly do want to know who's on the bus, but not for the reasons you stated.

Yes- of interest:

China's Big Tech companies taught Asia to pay by scanning QR codes, but made a mess along the way

https://www.theregister.com/2024/06/17/asia_qr_code_obsessio...

Those QR codes are validated online.

Transit has to work offline.

The time to process a payment at a retail outlet is ~1s+, the time required for public transport is usually <0.5s including mechanical release of barriers etc.

QRs are dramatically slower than NFC.

An always-online requirement is not feasible everywhere.

You can fail open. The QR code contained a signed ticket ID and expiry. You locally validate the signature and expiry and remotely attempt to validate reuse. If the remote validation is slow or fails just accept the ticket and log it.

That is what happens, however it exposes the transit company to a risk that many of them aren't willing to accept.

Reply on news.ycombinator.com