11 ms·

This is pretty cool! One thing that bothers me about every traffic simulation I've ever seen, though: all of the vehicles and pedestrians here seem to be obeyi

by ken 7y ago

This is pretty cool! One thing that bothers me about every traffic simulation I've ever seen, though: all of the vehicles and pedestrians here seem to be obeying the law. That's just not realistic -- especially on Mercer, which is blocked (both directions) every few minutes in rush hour by some jerk trying to make an illegal turn onto a packed street. I'd say the main causes of traffic blockages that I encounter during rush hour are drivers blocking the box, and pedestrians entering the crosswalk against a red hand. I also see a lot of lane sweeping, too, which I assume is from the influx of drivers from California (where it's legal). I hope traffic engineers aren't making real-world decisions based on simulations that follow all state laws perfectly, but I fear they are.

blincoln 7y ago
I agree with you. However, this may be obvious, but some of that could be due to people trying to follow Google Maps, Waze, or other similar navigation system directions where the routes are generated based on what other users have done. I drove in downtown Seattle rush "hour" traffic for the first time in almost a year earlier this week, and Maps was giving me all kinds of dangerous, traffic-jam-causing directions. Things like "make a left turn at an uncontrolled intersection, from a side street onto an arterial that's gridlocked for about a kilometer in either direction". Apparently it had been happening for awhile, because the city had installed a barrier across the median, and I couldn't have followed the directions even if I'd wanted to. IOW, it's not just drivers ignoring the law, it's tech companies explicitly instructing drivers to break the law and cause traffic problems that the simulations need to account for now.
- nkrisc 7y ago
  > it's not just drivers ignoring the law It is. If a driver comes across the situation you described, any action other than a right-hand turn means they should probably take a driver's ed course again. Regardless of what a robotic voice on their phone is telling them. Google maps once instructed my wife to do a U-turn on Lakeshore Drive. Nope.
  - myself248 7y ago
    Yes, and driver's ed should harp on the concept of ignoring the sat-nav if it's telling you obnoxious things. See my other comment. I don't think this concept is mentioned anywhere in the current curriculum, and I think a lot of people are ignorant enough of technology to obey it more blindly than they should.
  - blincoln 7y ago
    That's certainly the ideal approach, but I don't think it's realistic to plan for normal people behaving that way. By the time I realized that Google had given me a route that would not work, breaking out of it cost me 10 minutes of sitting in traffic going the wrong way. I think most people would take the "drive like a jerk" alternative at that point, because the sunk-cost illusion is hard to let go of. A self-driving car is basically just going to do what the mapping software tells it to as well, so the "bad instructions from tech companies" factor is a problem that needs to be addressed specifically anyway.
- myself248 7y ago
  > instructing drivers to break the law And the process for reporting a map error or unsafe maneuver instruction is way too complicated to do while moving, but can't be done after you've left the area, and there's no function to just submit a voice note. Related: Some time back, I gave my old TomTom to a not-very-technically adept friend. I figured a little introduction was in order, and at first, I asked her to interact with the unit while I did the driving. The first thing I did was ignore every instruction. A few minutes of https://xkcd.com/1837/ https://xkcd.com/1837/ ensued. Because I wanted to drive home the point, you won't break it by ignoring it. If you don't feel like making that turn, don't make it. The voice in the box will just recalculate, it won't get annoyed, it has infinite patience and can recalculate for as many maneuvers as you feel like missing. This is a crucial bit of understanding that I think many drivers lack, as they blindly try to follow impossible or unsafe maneuvers like the computer's word must be obeyed absolutely. If I had a button which could project thoughts into other people's minds, but _only one thought_ and once programmed the button can never be changed, I think I might set it to "It's okay, just go past it, turn around, and come back." I think a huge fraction of traffic snarls could be eased by spamming the hell out of such a button.
- caconym_ 7y ago
  "Maps apps" consistently give me crazy directions in Seattle, in particular things like trying to turn left onto a busy road from a side street when one block over there's an arterial with a light. I really think the prevalence of crazy directions and Uber/Lyft drivers blindly following them must be hurting traffic flow in aggregate. Not so much actions that break the law, but rather actions that are just pointless and stupid.
dabreegster 7y ago
I'd like to explore more realistic behavior at some point. Right now, vehicles will avoid starting a turn if there's not enough time left in the signal, but this is an optimistic estimate assuming nobody else is creeping along on the same turn: https://github.com/dabreegster/abstreet/blob/770507610caf4e4129b39b166c1a20ece9171de2/sim/src/mechanics/intersection.rs#L384 https://github.com/dabreegster/abstreet/blob/770507610caf4e4... Right now, it's hard to get a full day of simulation to complete at all, because vehicles gridlock on really short roads inferred from OSM. Once a realistic amount of traffic can get through at all, then I'd love to simulate some percentage of illegal behavior.
myself248 7y ago
I've had a lot of fun tweaking this setting in Cities:Skylines. There's a user-written mod called Traffic Manager Presidential Edition which lets you enable some (but not all) bad behaviors. The principle one is entering an intersection that they don't have room to leave, so they're still there when the signal changes and block the cross direction. (Is this AKA blocking the box? That sounds like a regional term.) This is needed to induce most forms of gridlock. I'd love if it had more support for jaywalking and vehicles stopping in travel lanes with their flashers on. (And then I'd love if I had a lightning-bolt tool where I could just smite them from on high. There probably is a mod for that, actually.)
- squeaky-clean 7y ago
  The feature, for anyone curious what the other rules it'll break are. [0] TMPE is such a great mod for improving the game's traffic simulation. I've spent a lot of time playing with timed traffic light systems. Cities Skylines will also automatically despawn vehicles to prevent massive gridlock that will break your city, and TMPE can disable this assistance for a truly difficult game. [0] https://tmpe.viathinksoft.com/wiki/index.php?title=Reckless_driving https://tmpe.viathinksoft.com/wiki/index.php?title=Reckless_...
- wizzwizz4 7y ago
  I still don't understand the concept of "jaywalking". Is there something wrong with crossing the road in the US?
  - setr 7y ago
    yes cars have dedicated lanes for driving bikes have dedicated lanes for biking legs have dedicated lanes for walking do NOT cross the lanes
    - scarejunba 7y ago
      Interestingly, the UK doesn't have these laws and has lower deaths per passenger mile.
    - deleted 7y ago
ibrault 7y ago
Another thing I'd be interested in seeing modeled are the people who squeeze into an exit lane at the very last minute. I've only ever commuted in the LA area but it's one of the biggest contributors to traffic by the freeway interchanges.
- brandonscott 7y ago
  There are studies that show merging late actually reduces congestion: https://www.nytimes.com/2016/10/13/us/why-last-second-lane-mergers-are-good-for-traffic.html https://www.nytimes.com/2016/10/13/us/why-last-second-lane-m...
  - bluGill 7y ago
    An Exit lane is probably a different situation from the one described though, and so different behavior is better.
    - ibrault 7y ago
      Yes, I figured I probably wasn't clear enough. I agree with the points in the article but I'm referring to a different situation. For example, the one that kills me every morning is where the 101 S turns into the 134, there are 2 dedicated lanes for the 134 on-ramp (so no zipper merge) but people wait until the last possible minute to force their way into the dedicated lanes and clog both those and the surrounding ones. Similar situation where the 170 S hits the 134.
- yellowapple 7y ago
  Yep. Happens all the time going northbound on 280 at the 101/280 interchange in SF. You'll always see at least one person clogging up one of the two 280 north lanes by trying to squeeze into the (almost always near-stationary) 101 north lanes. Then, further up 280, the same thing happens with the 6th Street exit, without fail.
ayberk 7y ago
I can't even be mad at people blocking the intersections anymore. I know it's not a valid argument, but if they don't do it, other people will and they'll be stuck there not moving at all. Seattle is a good example of how bad design can create incredibly bad traffic despite the fact that number of cars are actually not that high. Assign a cop to certain intersections would relief most of the traffic I presume.

by ken 7y ago

blincoln 7y ago

I agree with you. However, this may be obvious, but some of that could be due to people trying to follow Google Maps, Waze, or other similar navigation system directions where the routes are generated based on what other users have done. I drove in downtown Seattle rush "hour" traffic for the first time in almost a year earlier this week, and Maps was giving me all kinds of dangerous, traffic-jam-causing directions. Things like "make a left turn at an uncontrolled intersection, from a side street onto an arterial that's gridlocked for about a kilometer in either direction". Apparently it had been happening for awhile, because the city had installed a barrier across the median, and I couldn't have followed the directions even if I'd wanted to. IOW, it's not just drivers ignoring the law, it's tech companies explicitly instructing drivers to break the law and cause traffic problems that the simulations need to account for now.

nkrisc 7y ago
> it's not just drivers ignoring the law It is. If a driver comes across the situation you described, any action other than a right-hand turn means they should probably take a driver's ed course again. Regardless of what a robotic voice on their phone is telling them. Google maps once instructed my wife to do a U-turn on Lakeshore Drive. Nope.
- myself248 7y ago
  Yes, and driver's ed should harp on the concept of ignoring the sat-nav if it's telling you obnoxious things. See my other comment. I don't think this concept is mentioned anywhere in the current curriculum, and I think a lot of people are ignorant enough of technology to obey it more blindly than they should.
- blincoln 7y ago
  That's certainly the ideal approach, but I don't think it's realistic to plan for normal people behaving that way. By the time I realized that Google had given me a route that would not work, breaking out of it cost me 10 minutes of sitting in traffic going the wrong way. I think most people would take the "drive like a jerk" alternative at that point, because the sunk-cost illusion is hard to let go of. A self-driving car is basically just going to do what the mapping software tells it to as well, so the "bad instructions from tech companies" factor is a problem that needs to be addressed specifically anyway.
myself248 7y ago
> instructing drivers to break the law And the process for reporting a map error or unsafe maneuver instruction is way too complicated to do while moving, but can't be done after you've left the area, and there's no function to just submit a voice note. Related: Some time back, I gave my old TomTom to a not-very-technically adept friend. I figured a little introduction was in order, and at first, I asked her to interact with the unit while I did the driving. The first thing I did was ignore every instruction. A few minutes of https://xkcd.com/1837/ https://xkcd.com/1837/ ensued. Because I wanted to drive home the point, you won't break it by ignoring it. If you don't feel like making that turn, don't make it. The voice in the box will just recalculate, it won't get annoyed, it has infinite patience and can recalculate for as many maneuvers as you feel like missing. This is a crucial bit of understanding that I think many drivers lack, as they blindly try to follow impossible or unsafe maneuvers like the computer's word must be obeyed absolutely. If I had a button which could project thoughts into other people's minds, but _only one thought_ and once programmed the button can never be changed, I think I might set it to "It's okay, just go past it, turn around, and come back." I think a huge fraction of traffic snarls could be eased by spamming the hell out of such a button.
caconym_ 7y ago
"Maps apps" consistently give me crazy directions in Seattle, in particular things like trying to turn left onto a busy road from a side street when one block over there's an arterial with a light. I really think the prevalence of crazy directions and Uber/Lyft drivers blindly following them must be hurting traffic flow in aggregate. Not so much actions that break the law, but rather actions that are just pointless and stupid.

dabreegster 7y ago

I'd like to explore more realistic behavior at some point. Right now, vehicles will avoid starting a turn if there's not enough time left in the signal, but this is an optimistic estimate assuming nobody else is creeping along on the same turn: https://github.com/dabreegster/abstreet/blob/770507610caf4e4129b39b166c1a20ece9171de2/sim/src/mechanics/intersection.rs#L384 https://github.com/dabreegster/abstreet/blob/770507610caf4e4... Right now, it's hard to get a full day of simulation to complete at all, because vehicles gridlock on really short roads inferred from OSM. Once a realistic amount of traffic can get through at all, then I'd love to simulate some percentage of illegal behavior.

myself248 7y ago

I've had a lot of fun tweaking this setting in Cities:Skylines. There's a user-written mod called Traffic Manager Presidential Edition which lets you enable some (but not all) bad behaviors. The principle one is entering an intersection that they don't have room to leave, so they're still there when the signal changes and block the cross direction. (Is this AKA blocking the box? That sounds like a regional term.) This is needed to induce most forms of gridlock. I'd love if it had more support for jaywalking and vehicles stopping in travel lanes with their flashers on. (And then I'd love if I had a lightning-bolt tool where I could just smite them from on high. There probably is a mod for that, actually.)

squeaky-clean 7y ago
The feature, for anyone curious what the other rules it'll break are. [0] TMPE is such a great mod for improving the game's traffic simulation. I've spent a lot of time playing with timed traffic light systems. Cities Skylines will also automatically despawn vehicles to prevent massive gridlock that will break your city, and TMPE can disable this assistance for a truly difficult game. [0] https://tmpe.viathinksoft.com/wiki/index.php?title=Reckless_driving https://tmpe.viathinksoft.com/wiki/index.php?title=Reckless_...
wizzwizz4 7y ago
I still don't understand the concept of "jaywalking". Is there something wrong with crossing the road in the US?
- setr 7y ago
  yes cars have dedicated lanes for driving bikes have dedicated lanes for biking legs have dedicated lanes for walking do NOT cross the lanes
  - scarejunba 7y ago
    Interestingly, the UK doesn't have these laws and has lower deaths per passenger mile.
  - deleted 7y ago

ibrault 7y ago

Another thing I'd be interested in seeing modeled are the people who squeeze into an exit lane at the very last minute. I've only ever commuted in the LA area but it's one of the biggest contributors to traffic by the freeway interchanges.

brandonscott 7y ago
There are studies that show merging late actually reduces congestion: https://www.nytimes.com/2016/10/13/us/why-last-second-lane-mergers-are-good-for-traffic.html https://www.nytimes.com/2016/10/13/us/why-last-second-lane-m...
- bluGill 7y ago
  An Exit lane is probably a different situation from the one described though, and so different behavior is better.
  - ibrault 7y ago
    Yes, I figured I probably wasn't clear enough. I agree with the points in the article but I'm referring to a different situation. For example, the one that kills me every morning is where the 101 S turns into the 134, there are 2 dedicated lanes for the 134 on-ramp (so no zipper merge) but people wait until the last possible minute to force their way into the dedicated lanes and clog both those and the surrounding ones. Similar situation where the 170 S hits the 134.
yellowapple 7y ago
Yep. Happens all the time going northbound on 280 at the 101/280 interchange in SF. You'll always see at least one person clogging up one of the two 280 north lanes by trying to squeeze into the (almost always near-stationary) 101 north lanes. Then, further up 280, the same thing happens with the 6th Street exit, without fail.

ayberk 7y ago

I can't even be mad at people blocking the intersections anymore. I know it's not a valid argument, but if they don't do it, other people will and they'll be stuck there not moving at all. Seattle is a good example of how bad design can create incredibly bad traffic despite the fact that number of cars are actually not that high. Assign a cop to certain intersections would relief most of the traffic I presume.