"All you've done is push the problem to a different place. Instead of "wasting" 15 seconds here and there while driving north, you waste a minute every time you drive east.
Check it out. Let's suppose you drive 3 blocks east and then 12 blocks north to get to work. Pretty typical -- you get to the main road as fast as you can, use it, and then get off.
If the lights are all 60/40, let's say you waste an average of 15 seconds at every light going north. If you are going east, you wait an average of 20 seconds, just a little bit longer.
3 blocks east, 12 blocks north = 3*20 + 12*15 = 240 seconds = 4 minutes at intersections
Now let's switch the whole system to 90/10. Now when you drive north you only wait an average of 5 seconds at an intersection (woo hoo!). But, when you drive east each intersection takes a full minute while all the northbound traffic drives go by.
3 blocks east, 12 blocks north = 3*60 + 12*5 = 240 seconds = 4 minutes at intersections
BUMMER, you just wasted the exact same amount of gas!!!
You see, your assumption break down when you look at the actual system and not at just one intersection. Now do you see why traffic lights don't always work like you think they should?"
None of this makes any sense. You are saying you go 3 blocks east and 12 cars north but that is not the ratio of drives that go that way. It would be 3 blocks east and 30 blocks north because for every driver that goes east/west there are 10 that go north/south, so that would not be the ratio. And I'm not talking about blocks, or city blocks I'm talking about suburb roads and such. The lights are wasing time and gas I know for a fact because I have seen it thousands of times.
Here is an example. Suppose a north/south light goes green for 30 seconds and red for 20 seconds, which is what many are like. Over 2:30 of time the light will turn red 3 times for north/south drivers, and 3 times for east/west drivers. There are 20 drivers going north/south every 50 seconds and 2 drivers going east/west every 50 seconds. It should only turn red 1 time for north/south drivers and 1 time for east/west drivers during the 2:30. The light should be green for 2:10 north/south, and then turn red for :20 for north/south.
Watch the time and gas that is saved. When 20 cars getting stopped twice before the 2:10 mark they waste 20 seconds each. Which is 400 total seconds every red light. So multiply that by 2 and it is 800 total seconds wasted for north/south drivers. If the light only turned red once at the 2:10 mark those 800 seconds for 40 cars wouldn't be wasted.
2 cars going east/west arrive in the first 50 seconds, so they lose 100 seconds each because they have to wait until the 2:10 mark for the green light. 2 more cars going east/west arrive in the 2nd interval of 50 seconds, so they lose 50 seconds each. That is 200 + 100 seconds 300 total seconds wasted for the east/west drivers and 0 seconds wasted for the north/south drivers. The other alternative which is what it is is 800 seconds wasted for the north/south drivers and 0 wasted for the east/west drivers. Changing the light to one red every 2:30 saves 500 total seconds(800-300) for 40 drivers. While only causing a delay for 4 drivers.
How can you tell me this is not more gas/time efficient?
Topic: What don't you understand and it bugs you? (Read 38944 times)