5 ms·

I doubt this has much to do with traffic. It can be explained by another observation: on average you spend more time in slow lanes. The checkout at a supermark

I doubt this has much to do with traffic. It can be explained by another observation: on average you spend more time in slow lanes. The checkout at a supermarket has the same phenomenon. Let's say with 50% probability you choose a line that takes 10 minutes and with 50% probability you choose a line that takes 20 minutes. On average now 67% of the time the other line will move faster.

yequalsx 11y ago
I believe your analysis is incorrect. There is a 50% chance the other line will move faster. With no additional new information, once you've chosen a line to stand in, the probability you chose the slower line has not changed.
- Retric 11y ago
  That's after 1 cycle. Assume you chose once per week for 10 years = 520 trips. So, 50% of your trips (260) you would pick the fast lane and 50% of the trips you would pick the slow lane (260). The sum of your slow trip time is 20 * 260 = 5,200 minutes and your fast trip time takes 10 * 260 = 2,600 minutes. So, out of a total wait time of 5200+2600= (7,800) minutes you spent 2/3 of it in the slow lane and 1/3 of it in the fast lane.
  - Nadya 11y ago
    I think the last statement of the parent is causing the confusion. >On average now 67% of the time the other line will move faster. This should be: "On average, you spend 67%~ of your time in the slower lane." On average the other lane is still only faster 50% of the time assuming the odds are truly 50/50 - but you spend 67% more time in the slower lane.
    - JoeAltmaier 11y ago
      Gotta be careful with the word 'time'. 50% of your trips, the other lane is faster. 67% of the time, its faster.
  - yequalsx 11y ago
    But this isn't what the parent wrote. I think it is what he/she meant but it isn't what was written. The probability that the other lane is faster is still 50%.
    - deleted 11y ago
      [deleted]
- wlesieutre 11y ago
  There's a 50% chance of a given lane being the fast one, but you'll spend twice as long in the slow lane if you're stuck there. Thinking of total time for grocery store lines may feel unnatural, but it's certainly the perspective that makes sense on a road. I wouldn't start a 200 mile trip by saying "I'm going to spend this trip in the right lane," I'd do some of my driving in each. And if I drive 100 miles in the fast lane and 100 miles in the slow lane, I'll have spent >50% of my time in the slow lane, even if my odds of picking the right one are 50/50 at any given moment.
panarky 11y ago
"The utility of switching lanes while stuck in traffic" https://news.ycombinator.com/item?id=7622626 https://news.ycombinator.com/item?id=7622626 Counterintuitively, in stop-and-go traffic everybody spends more time watching others pass them than passing others. Let's say you have to drive 100 km. Half of the distance your lane moves at 100 km/h, and the other half your lane creeps along at 10 km/h. So you'll spend 50 / 100 + 50 / 10 = 5.5 hours in the car, at an average speed of 18.18 km/h. For every one minute you spend passing other cars, you'll spend 10 minutes watching other cars whiz by you! Even though the fast and slow distances are evenly distributed, all drivers perceive that they're in the wrong lane.

yequalsx 11y ago

I believe your analysis is incorrect. There is a 50% chance the other line will move faster. With no additional new information, once you've chosen a line to stand in, the probability you chose the slower line has not changed.

Retric 11y ago
That's after 1 cycle. Assume you chose once per week for 10 years = 520 trips. So, 50% of your trips (260) you would pick the fast lane and 50% of the trips you would pick the slow lane (260). The sum of your slow trip time is 20 * 260 = 5,200 minutes and your fast trip time takes 10 * 260 = 2,600 minutes. So, out of a total wait time of 5200+2600= (7,800) minutes you spent 2/3 of it in the slow lane and 1/3 of it in the fast lane.
- Nadya 11y ago
  I think the last statement of the parent is causing the confusion. >On average now 67% of the time the other line will move faster. This should be: "On average, you spend 67%~ of your time in the slower lane." On average the other lane is still only faster 50% of the time assuming the odds are truly 50/50 - but you spend 67% more time in the slower lane.
  - JoeAltmaier 11y ago
    Gotta be careful with the word 'time'. 50% of your trips, the other lane is faster. 67% of the time, its faster.
- yequalsx 11y ago
  But this isn't what the parent wrote. I think it is what he/she meant but it isn't what was written. The probability that the other lane is faster is still 50%.
  - deleted 11y ago
    [deleted]
wlesieutre 11y ago
There's a 50% chance of a given lane being the fast one, but you'll spend twice as long in the slow lane if you're stuck there. Thinking of total time for grocery store lines may feel unnatural, but it's certainly the perspective that makes sense on a road. I wouldn't start a 200 mile trip by saying "I'm going to spend this trip in the right lane," I'd do some of my driving in each. And if I drive 100 miles in the fast lane and 100 miles in the slow lane, I'll have spent >50% of my time in the slow lane, even if my odds of picking the right one are 50/50 at any given moment.

panarky 11y ago

"The utility of switching lanes while stuck in traffic" https://news.ycombinator.com/item?id=7622626 https://news.ycombinator.com/item?id=7622626 Counterintuitively, in stop-and-go traffic everybody spends more time watching others pass them than passing others. Let's say you have to drive 100 km. Half of the distance your lane moves at 100 km/h, and the other half your lane creeps along at 10 km/h. So you'll spend 50 / 100 + 50 / 10 = 5.5 hours in the car, at an average speed of 18.18 km/h. For every one minute you spend passing other cars, you'll spend 10 minutes watching other cars whiz by you! Even though the fast and slow distances are evenly distributed, all drivers perceive that they're in the wrong lane.