Small Actions at Scale

Throughout the process of developing MetroChange, we’ve thought a lot about the pricing and bonus system of MetroCards, the User Interface design of the MTA vending machines, and other factors that result in leftover value on MetroCards. We’ve talked about what factors make it difficult for people to refill their cards, or how refilling doesn’t even make sense if you’re on your way out of New York.

And we know there is a significant amount of value there. The MTA itself estimates the value of lost or unusable MetroCards at approximately $52 million a year. So we thought, what if this money, or even a portion of it, could go towards something more meaningful than just being subsumed back into the larger MTA system? What if people could maintain authority over where the value of the cards they bought ends up?

The corollary to this potential value is what people would actually do. We envision a system that makes donating a simple and immediate action, and one that easily integrates into people’s daily habits. However, instead of being a one-to-one exchange, we envision a system that has the ability to multiply the effects of a single action, by matching the donation, or scaling it up by combining it with many other people’s donations in different places and different times.

More than 58 million people travel through the Times Square subway station each year. Imagine if just one percent of those people found themselves at a MetroChange kiosk, and decided to donate the money remaining on their MetroCard. There is a huge potential at just one location, but imagine that potential added to money collected in other locations, especially ones outside the subway system, like airports, train stations, and hotels.

We are not the first to consider the idea of donating the value leftover on a transit card. The Bay Area Rapid Transit (BART) and its partner organization the East Bay Community Foundation run a program called Tiny Tickets, that allows people to mail in their old BART cards for donations. The East Bay Community Foundation works with BART to ensure that the value is matched and donated to qualifying charities that operate within the vicinity of the transit line.

We believe that this model provides an effective example to build on. We’d like to create a way so that people wouldn’t necessarily have to take the effort to mail their tickets in, but that the act of donating would easily integrate into their daily routine, or as they’re  leaving the city. We hope that MetroChange continues to develop, and integrates donating to charity into people’s daily routines.

Thanks, Future Plans


This is just a quick note to say a huge thank-you to everybody who has been in touch in the last few days via Twitter (@metrochange) and e-mail ( to offer support, feedback and ideas.

MetroChange has been covered the New York Post, The Huffington Post, GOOD magazine, The Daily Beast, The Atlantic, Laughing Squid, PSFK, Gothamist and by many other bloggers and sites. We couldn’t be more grateful - the project seems to have really hit a nerve.

By way of an update; we have been taking a couple of days to relax and recuperate after a long and tough semester. Next week the three of us will be back together in New York where we will take our overflowing bucket of ideas and start to plan the next few months.

We have some obvious priorities; seeking the support of the MTA, speaking with other potential sponsors, working on software and the physical device, speaking with charities, getting feedback from you. We will keep the blog up to date as things fall into place.

We will most definitely need your continued help and support - so please follow us on Twitter or drop us an e-mail. We will do our very best to get back to everybody who contacts us as quickly as possible.

Again, thanks for your support.

Team MetroChange - Stepan, Genevieve, Paul.

Photos of MetroChange

MetroChange - Donate

Hello. We’ve added some more photos to our Flickr set of MetroChange. You’ll see the early technical work we did, the first prototype, and the kiosk we completed recently for the ITP Winter Show - our first full working model. If you are blogging about MetroChange and can’t find a suitable image just mail us and we’ll see what we can do.

Thanks for all the great feedback on the project; we are excited to see where this adventure goes next. 

Partners Wanted for MetroChange

In the last few months we’ve researched and developed a system that could act as a charity platform using New York City MetroCards - essentially giving people a choice to use the remaining value on their cards as a public good. 

We believe that MetroChange, if it was rolled out in the city, would allow people who use the New York City subway system to express a preference about what happens to the awkward, remaining value left on their MetroCards. MetroChange quantifies this preference, gives people an alternative to the trash can - making a claim on a portion of what, at scale, is a significant chunk of change.

The key part of this system is obvious; swiping your card, saying that you want to donate the remaining value to charity, then depositing the card in a kiosk doesn’t actually make “money” real. The money is already part of the MTA’s economy and needs to be converted into useful value.

There are two possibilities here; the MTA returns this loose change, or somebody else matches the amount without involving the MTA.

In the situation where the MTA sponsored MetroChange they would  make a donation for the amount of value seen at MetroChange kiosks each month; essentially returning missing/unused value back to the community where it originated. In many cities around the world, excess value and unclaimed change from tickets/cards is donated to charity - so MTA would really just be doing what many other authorities already do.

Another possibility would be that a foundation or organization with an interest in public transportation, urban planning and design matches the value of money seen at MetroChange kiosks and donates it to a charity each month. 

We are really interested in pursuing both these approaches - or maybe there are other approaches that we just haven’t thought of. If you work with MTA, have contacts with MTA - or you work with an organization involved in transportation, transportation policy, urban planning (groups with a stake in the future of New York city’s urban fabric) please mail us at or twitter @metrochange.

MetroChange at ITP Winter Show 2011

We’re very proud that MetroChange has been selected to be included in the ITP Winter Show. This is a great chance for us to show the progress we’ve made in the last few months and get feedback. The show is on Sunday the 18th of December from 2-6pm and again on Monday from 5-9pm. 

Prototyping the MetroChange Kiosk

After weeks of tinkering, here it is. MetroChange in its full, decal glory.

MetroChange Kiosk

Prototyping the MetroChange Reader

First Prototype

One of the key challenges involved in building a system that involves MetroCard is reading the MetroCard itself.

At first we didn’t have any detailed technical knowledge about how MetroCard worked. Our first “prototype” was simply a Square card reader. We plugged the reader into the line-in of a computer and swiped the card back and forward - producing a crude audio signal. This was exciting, we could hear something even if we didn’t know what it meant.

A Brief Introduction to Magnetic Stripe Cards

All magnetic stripe cards work on similar principles. Information is stored on one or more magnetic “tracks” that run horizontally across the black magnetic stripe. When you pass the card through a reader, a tape head (just like the one in a cassette tape player) which has been aligned to the position of the track, converts the magnetic field into a current, which is then interpreted.

Standard magnetic stripe readers are aligned to a particular physical position or “track” (usually track 3), but the MetroCard uses a different track (track 1-2) to store some information, and track 3 to store other information. The changeable information, including the value of the card is written on track 1-2 (standard track 1 & 2 combined) and permanent info (such as ID of the card, ID of the vending machine and so on) is written on track 3.

Second Prototype

We researched previous attempts to decode the information on a MetroCard. We found a presentation to the Chaos Computer Club and two articles in 2600 magazine by Joseph Battaglia. The presentation gives an overview of magnetic stripe reading with specific reference to the MetroCard. The articles detail a system that listens to an audio input on a computer and decodes MetroCard information as binary. We found software by Wincent Balin that implements Joseph Battaglia’s code for reading the cards under a GPL license on Github. We used this information and software as the basis of our prototype. 

We built a magnetic card reader using a magnetic tape head from a cassette tape player. We mounted the tape head in our prototype kiosk, and aligned it to the position of track 1-2 on the MetroCard; 0.133” from the base of the stripe.

MetroChange - Tape Head

The output of the circuit was connected to an audio jack which was connected to a computer. We monitored the signal in a standard audio recording application (Audacity), but found that the signal was incredibly weak; so we build an amplification circuit.

MetroChange - First Amplifier

We monitored the signal again. Swiping the card back and forward produced a signal similar to the one from the Square reader - but much louder. A step forward.

We spent days trying to get the MetroCard software from github to work with our magnetic reader and amplification circuit but the binary being outputted from the software was not consistent. We guessed that the signal from the amplifier was distorted and so the software was failing to interpret the signal.

We decided to build a different amplifier to test if this is the case.

Working Prototype

We rebuilt the card reader using magnetic stripe amplifier circuitry designed by L. Padilla. The 

MetroChange Reader - Stepan Checking Binary

We checked the binary coming from the software, and saw that we were now getting a known prefix (“start sentinel”) of 0011010111 .

Magstripe Reader

We know from the 2600 article that the information containing the value of the card should be offset by 66 binary digits offset and be 16 digits long.

We tested several cards and discovered that translating binary value at this position to decimal gave exactly double the value on a MetroCard. So, to get the value of the card in cents it is necessary to convert binary to decimal and divide the result by 2. 

We had successfully built a working MetroCard reader.

Next Steps

We learned a huge amount by building our own card reader and using the software from github; as a first working prototype this approach works well. We’re now investigating new designs for the card reader that don’t involve using a PC. We’ll write about this when we have something working.

Prototyping the MetroChange User Experience

We’ve been continuing to develop the MetroChange concept, and starting to prototype how it will work. 

Ultimately we want to end up with a system that allows a person to transfer the remaining value of their MetroCard into a central fund. This fund would be matched by an organization and donated to charity once a month. 


There are obviously lots of challenges involved making this a reality. We need to explain the purpose of the service. We need to be able to read the value of a MetroCard and transmit that value to a central system. We need to take the physical MetroCard out of circulation somehow. We need to house the physical components in a rugged kiosk. 

And so on. 

The challenges roughly divide into two categories; user experience and technology - making it smooth and making it actually work. We’ll cover the UX prototyping here, then the technical prototyping in a later article.

Prototyping the User Experience

We started to design how the MetroChange kiosk would work by sketching what we felt was the most basic implementation; a card reader, a computer, an LCD screen to give feedback and a receptacle to store the MetroCards. 

MetroChange - Prototype

We built a prototype of this system, and walked through the key interactions. 

The person swipes their MetroCard and the value from the card is read. 

The person is given feedback through the LCD screen. 

MetroChange - Feedback

We need to make sure that cards aren’t swiped over and over again, so the card is taken out of circulation.

MetroChange - UX Prototype 3

MetroChange - UX Prototype 4

Lessons Learned

We learned a lot by testing with this simple prototype.

The physical action of swiping the card should mimic the swipe action at an MTA turnstile (away from the user) or value-checking machine (right to left). Ours was close, but not close enough to feel really familiar. 

The act of swiping the card and taking it out of circulation should work together. Asking the user to deposit their card in a receptacle worked, but is too loose. We thought that a way to destroy or demagnetize the card would work. We thought about a mechanized system to take the card from the user. 

We know that the MetroChange system could be most interesting with many people using it across many locations. The feedback we gave the user on the LCD screen could give a sense of contributing to an the central fund - maybe the total current value of the system could be shown, or the amount donated today. The experience didn’t feel connected to the wider system.

We learned that the visual look of the kiosk would be important. Even if the service becomes well-known, the kiosk has to be distinctive. Continuing to use transparent acrylic would probably mean that the kiosk would literally disappear in the urban landscape.

We’re going to take these lessons forward into the next version of the prototype. 

Introducing MetroChange


In our research we saw that the MetroCard pricing system, vending machine user interface and customer behaviour work together, resulting in small amounts of value remaining on MetroCards. These cards are often lost or thrown away.

We started to imagine ways in which the $52m of lost and missing value could be reduced, and tried to identify ways in which we could intervene.

Intervening in the MetroCard System

Re-designing the pricing structure of the MetroCard system would change the types of inefficiencies in the system - as would changing the vending machine user interface - but we don’t have any influence at these points in the system.

We started to think about points before and after the purchase of the MetroCard - influencing consumer behaviour and coping with remaining value on cards when they are actively discarded by consumers.

Our Interventions

We decided that we would try to raise awareness of MetroCard pricing structure by publishing the results of our research. We also decided to design a system that would encourage consumers to make an active decision about the value remaining on their cards as they go to throw them away, or leave the MTA system. We have called this system MetroChange.

MetroChange allows a customer to take any value remaining on their MetroCard and put it to good use. The customer swipes their MetroCard at a MetroChange kiosk and any remaining value left on their card is transferred to a central fund. This fund is donated to a charity once per month. The physical card is taken for recycling.

How Does MetroChange Work?

MetroChange kiosks are located at heavily used subway stations, especially those where tourists and occasional users of the subway transition out of the subway system - transferring to an airport or regional train service.

The customer realizes that they have a small amount of unused value on their card. They swipe their card at the MetroChange kiosk. The value from their MetroCard is recorded by the kiosk and transmitted to a central fund. Value that would otherwise have been lost is now quantified and can be put to good use. The customer’s physical MetroCard is taken for recycling.

Each time a customer donates the value remaining on their MetroCard, the central fund increases in value. From here a matching organization steps in. Each month, the value of our central fund is converted into real money - this money is distributed to one charity. The fund starts again from zero, ready for customers to donate using their MetroCards.

Making It Real

We have continued to refine the MetroChange concept in the last few weeks. We’ve now begun to think about the user experience in detail and prototype the system. We’ll write about our progress soon.

MetroCard Intercept Survey

Target Market/Customer

We know from our breakdown of the MetroCard pricing system that in many cases customers are left with remaining value on their MetroCards. We surmised that waste in the system was probably not distributed evenly - some users of the system are more likely to be left with value remaining on their MetroCards, collectively adding up to $52 million a year.

Many native New Yorkers who have a regular travel schedule purchase weekly or monthly MetroCards - where wasted monetary value isn’t an issue, since they pay a one time fee up front for an unlimited ride time-based card.

It’s Pay Per Ride tickets, where you pay for rides by the dollar that are the source of waste. We surmised that tourists and infrequent users of the subway were likely to purchase these types of MetroCards, so we did some field research to validate that this was likely the case.

What we did

We chose a location where tourists/travellers were likely to use the subway system on their way out of town, specifically the Howard Beach terminal where the subway meets the AirTrain to JFK. We drew up a simple questionnaire and spent 1 hour surveying people as they transitioned from the subway to the AirTrain.

Some key questions we asked were:

  • Are you an NYC resident? 
  •  Do you have a MetroCard? 
  • If you bought a Pay Per Ride, what was the initial value you purchased? 
  • At any point, did you refill the MetroCard or buy another MetroCard? 
  • How much value do you estimate remains on the card currently? 
  • If an option existed, would you ever donate the remaining value on your card to charity?

We spoke to 20 people in one hour. 16 people were using Pay Per Ride tickets, 3 people were using time-based cards or unlimited ride cards and one person did not have a MetroCard. Most people who bout a Pay Per Ride card bought a $10 card initially. We asked the people using Pay Per Ride cards to tell us how much was remaining on their card. We also asked them if they would be willing to donate this remaining value to a charity before they discarded the ticket.


The combined value remaining on the Pay Per Ride cards was $29.65. One person had $13 remaining on their card. All the participants said that they’d be willing to use the remaining value on their cards for a better purpose - e.g. donating it to charity, or pooling the money somehow.


Even though the survey was very small and simple - it points us in a useful direction.

We appear to have correctly identified a group of users - tourists - who don’t get the maximum value from the MetroCards, resulting in waste. Knowing who these people are allows us to identify more locations where we can intervene. We plan to target exit points from the city, where tourists will pass through once they have no more use for their MetroCards. Some of these exit points are airports, train stations, and bus depots.

The value of the waste we identified at just one of these locations was significant; If you scale one hour up to a day the value is significant. If you think about multiple locations, then you really can imagine recovering significant amounts of value.

Getting the Most from MetroCard

If you’ve ever visited or lived in New York City you’ll be familiar with the MetroCard. These little cards are used by millions of people each day to access the subway and bus system. In this project, Stepan Boltalin, Genevieve Hoffman and I have broken apart the MetroCard pricing structure with some interesting results. Short version - don’t buy the $10 MetroCard.

Union Square - Metro Card Reader 2

The Missing Millions in the MetroCard System

The MetroCard system has evolved over nearly two decades - it uses some pretty old technology (a magnetic stripe on the card is read at a turnstile, which updates the value on your card) and a slightly odd fare structure ($2.25 per ride plus a 7% bonus when you spend $10 or more on a MetroCard) which combine to create some unfortunate results; small amounts of value left on cards when they’re discarded.

According to the MTA the small amounts of value on cards when they’re thrown away or lost adds up to $52m (yes, million) per year. So much money goes missing that the MTA are set to introduce a $1 green fee to encourage riders to hang on to their cards. Our project’s goal is to examine the causes of this “missing” money in the MetroCard system from a number of different angles. After all, $52 million could be put to better use and $1 per card seems like an awful lot of money at scale.

The Ever-Changing MetroCard Pricing Structure

(This section is a little dense, but bear with us.) The MTA Metrocard was first introduced in 1993 with a trial run of 3000 cards. In 1998 they introduced the MetroCard Bonus giving you a 10% bonus on cards of $15 or more. At this time a single ride using a MetroCard cost $1.50. In May 2003, subway fares increased from $1.50 to $2.00. The bonus increased to 20% for any ticket amount $10 and over.

In March 2008, the MetroCard Bonus decreased to 15% for purchases of $7 or more. In 2009, subway fares increased from $2.00 to $2.25 per ride. In December 2010, the bonus decreased to 7% for tickets of $10 or more. This is the pricing structure that applies to the pay per ride MetroCards today.

The MetroCard system has changed almost constantly since its introduction - and like most transit systems has gotten significantly more expensive over time.

The $10 MetroCard is Not Your Friend

Even a quick scan of the MetroCard pricing spreadsheet we’ve put together shows some significant amounts of remaining value on cards. Let’s look at the popular $10 MetroCard as an example; a card that’s popular among visitors to New York.

A customer purchases a MetroCard for $10 and gets $0.70 of a bonus making the card worth $10.70. At a price of $2.25 per ride, the customer gets 4 rides leaving $1.70 remaining on the card. To get another ride the customer needs to add at least $0.55.

MTA Interface Round 2 - 09

Adding value using the MetroCard vending machine is a significantly longer process than buying another $10 card - and adding whole dollar values like $10 and $20 still gets priority. 

Getting the Most from MetroCard

Our goal is to find ways of getting the maximum number of rides on the New York Subway while reducing the small amounts of remaining value left on our MetroCards - avoiding problems like the ones the $10 card introduces.

Working in increments of $1 and $0.25 we identified the MetroCard values that result in the maximum number of rides for consumers with as little remaining value as possible. We also identified the MetroCards where the value of the remaining value is covered by the MTA’s own bonus.

We think the results are interesting. Check out the breakdown of the MetroCard pricing structure in this spreadsheet.

As you’ll see, the $10 MetroCard offers the same number of rides as a $9 MetroCard. There’s no “bonus” but 4 rides is still 4 rides. A $20 MetroCard gives the consumer a bonus of $1.40, 9 rides with $1.15 remaining on the card. They could spend $19, get 9 rides with only 8c remaining on the card.

There are several price points where the user gets the same number of rides as they would at a higher price point, with minimal remainder - a consumer could spend $14.75, get $1.03 as a bonus - 7 rides with 3 cents remaining; any remainder is essentially covered by the “bonus” given by MTA. You pay less, you get the same and if you happen to lose or throw away your card the MTA are paying for the remaining value on the card.


We start to see that some of the problems of missing money in the system are a product of decisions by MTA themselves. The pricing structure leads to uneven values and remaining value on cards. The design of the vending machines works contrary to adding small values, or getting a specific number of rides. It’s not wrong, in our opinion, to start questioning whether adding another $1 on to the purchase of each MetroCard is valid.

Next Time You’re In New York

Use our MetroCard pricing spreadsheet to find a card that offers you enough rides for the time you’re in town, and reduces the chances of you being left with money remaining on your card.

Next Steps

We’re continuing this project - we hope to find more ways of eating into these odd problems with the MetroCard system upstream. After that we’ll devise ways of using any remaining value that is left on cards in a more productive way.