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Lean, Poka Yokes, and Taxi Cabs

Recently, a study in New York City found that nearly three quarters of cabbies had charged an out-of city rate for rides within the city, at about twice the cost to the passenger.

Now, the actual numbers come out to 1.8 million out of 360 million trips. The article I saw in the New York Times is titled New York Cabs Gouged Riders Out of Millions. It is certainly a loaded title, obviously intended to outrage city dwellers and get them to dive into the article.

If they do take the plunge, the find that about 3,000 drivers overcharged at least a hundred times during the 26-month study. Another 33,000 did it at least once.

It is clear to me that the system is broken. Some cabbies defended themselves saying that the two code buttons are next to each other, and make it easy to accidentally press the wrong one. The ones doing it over a hundred times might have sausages for fingers, but more likely, they are dishonest. For the rest, though, I am surprised that the number isn’t higher. I did a quick math exercise and found that the average cabbie would have pressed the button 17,000 times in that period, without overtime (about 30 fares per day). One time would be a 99.9941% quality rate. That’s quite a few sigmas. (Note: Even a hundred times is over 99% quality.)

As I was reading the article, I kept thinking, “Why don’t they poka yoke this problem?” The article, at the end, did offer some ideas. The interim solution proposed is to have a screen face the passenger that would require acknowledgement of the out of city rate. Not perfect, since it still requires an extra step, but an improvement.

Finally, in the last paragraph, the article mentions that the city will eventually require GPS based meters that won’t need any human input. Nice to see that they are putting some thought into a method to prevent mistakes.


Regardless of what the city decides–screens vs. GPS systems, immediately retrofit all cabs vs. new cabs only–, there will be a cost. With 48,000 cabs operating in the city, the price tag climbs quickly. At a conservative estimate of $200 per cab, the cost is about $10 million.

My first thought is that the chronic overchargers should be weeded out. It is an integrity problem, not a performance problem. A decal asking passengers to report drivers incorrectly charging the higher rate could help with this. This higher risk of being caught would reduce fraud.

For the others, though, a flip-up plastic cover glued over the higher rate button would prevent the unintentional overcharges at a fraction of the cost of the GPS solution.

The Lean lesson is to not jump to expensive, technology based solutions right away. Try something cheap and easy first. If it doesn’t work, then, and only then, add more (necessary) complexity. If the plastic cover solution does work, though, I’d be happy to take a percentage as a payment for my consulting effort. So what’s 10% of the $10,000,000 the cabbies could save?


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