科学与数学traffic-simulation.de
交通流微观模拟
Microsimulation of Traffic Flow
2019 — 2022，它一次次回到首页
黑点是上首页（≥ 50 分）的那次投稿，空心点是没冲上去的投稿，点越大分数越高。
导读
这个页面是一个可交互的交通流微观模拟器，默认展示环形道路场景，可把车辆、红绿灯、路障和限速等元素拖入场景，观察拥堵如何自发形成和扩散。它把“幽灵堵车”、交通波等抽象概念变成可玩的小实验，常被用来讨论驾驶行为、车道数和限速对通行效率的影响。
为什么经久不衰：它用极简交互直观揭示了拥堵往往由驾驶行为和微小扰动引发，这种“亲手做实验”的启发感让它多年后仍值得反复把玩。
HN 评论精选
提高加速度、降低减速度有助于减少交通波和拥堵。
这个模拟很好地展示了提高加速度如何减少拥堵。2m/s² 相当于 5mph/s，帮助很大：前车能更快让开。迟缓的加速虽然更接近我在路上看到的情况，却会导致堵死和交通波。也许更令人惊讶的是，降低（舒适的？）减速度比提高减速度更能让交通保持顺畅。
jdashg查看英文原文
This does a great job of demonstrating how increasing acceleration decreases traffic. 2m/s/s is 5mph/s, and helps a lot: Cars in front get out of the way faster. Lazy acceleration, while more accurate to what I see on the road, causes gridlock and traffic waves. Perhaps more surprisingly, /reducing/ comf(ortable?) deceleration keeps things running smoother than higher values.
模拟揭示驾驶行为与交通流量之间存在反直觉关系。
我很喜欢这些在线交通模拟器，尤其喜欢看人们如何操纵它们来迎合自己对“正确”驾驶的看法。没有简单答案：激进驾驶不好，跟车太近也不好。但看看调高加速度并缩小车距时会发生什么，再反过来试试。这类小模拟告诉我们，坏驾驶其实对交通流有好处。一个很有意思的教训是，速度似乎与交通流量基本无关。只要人们不留空隙、紧密跟车并像赛车手一样加速/刹车，净流量就和速度脱钩了。
sandworm101查看英文原文
Lol. I really enjoy these online traffic simulators. Specifically, I like seeing how people manipulate them to suit their own ideas about "proper" driving. There is no easy answer. Aggressive driving = bad. Tailgating = bad. But see what happens when you crank up the acceleration and decrease distance between cars. Then do the opposite. Simple little simulations like this teach us that bad driving is actually good for traffic. One very interesting lesson is that speed seems largely irrelevant to traffic flow. So long as people don't leave gaps, that they all follow each other closely and accelerate/brake like racers, net flow is divorced from speed.
卡车微小相对速度超车造成巨大拥堵，被超车者略减速可大幅提升整体效率。
很烦人的一件事是“大象赛跑”：卡车以极小的相对速度并排超车（大概因为都卡在限速器上，但其中一辆校准略占优）。尤其在双车道，它们会堵住所有人。假设卡车长16m，从另一辆后方10m开始超车，并到前方10m，超车距离36m。相对速度1mph时，这要80秒。与此同时，后面的小车都被迫退出巡航，比理想速度低10mph（小车限速70，卡车60）。80秒乘以10mph，相当于整体行程多10秒。不算巨大，但会在队列所有车和一次行程中多次卡车超车中累积。关键是，如果被超的卡车松一mph油门，超车时间减半，自己只损失40秒少1mph，不到一秒行程时间。所以被超时，稍让一让的“利他”举动会以几十上百倍回报其他道路使用者。更不用说几十辆车减速后留下的行波会长时间拖慢整条路。
adhesive_wombat查看英文原文
One thing that really annoys me is "elephant racing" where trucks battle to overtake at very small relative speeds (probably because they're both on their limiters but one has a slight calibration advantage). Especially on 2 lane roads where they block everyone while doing so. Say a truck has a length of 16m, and starts the overtake 10m behind another one, and merges back in 10m in front. So that's an overtake distance of 36m. At 1mph relative speed, this takes 80 seconds. Meanwhile, the cars behind the truck have all had to drop out of cruise and are now doing 10mph under their preferred speed (car speed limit is 70, lorries are 60). So that 80 seconds and 10mph under is 10 seconds of overall journey time. Not enormous, but it multiplies across all the cars in the queue, and across the number of lorries making this move in a journey. However, the point is that if the overtaken lorry could just ease off the throttle by a single mph, he'd halve the overtake time, at a cost to himself of 1mph less for 40 seconds, which is less than a second of journey time. So, when overtaken, a very minor "altruistic" gesture on the part of the shower lorry pays back dozens or hundreds of times over to other road users. And that's without considering the travelling waves that linger after dozens of cars slow down from a rolling roadblock and can make the whole road slower for everyone for a long time.
增加车道可能因换道湍流恶化交通，模拟可演示这一点。
这太有趣了！作为有城市规划背景的人，朋友常固执地说“为什么城市不直接多修几条车道？”我得解释不是这样，更多车道会造成更多湍流。你可以用这个模拟试试！在某个道路场景里弄出很多车道，然后给系统一个“冲击”：把某个滑块推到造成拥堵，再调回来。看它要多久才清空。问题是车辆开始换道并造成混乱。美国有很多这类失败。
a1371查看英文原文
This is delightful! As someone with urban planning background, my friends often stubbornly bring up in the conversation that "why doesn't the city just build more lanes on the roads?". I have to explain how that's not how it works and the more lanes cause more turbulence. You can try it with this! In one of the road scenarios make lots of lanes. Then give the system a "shock". I.e. move one of the sliders until you cause a traffic, then move it back. See how long it takes for it to clear up. The problem is that cars start changing lanes and cause mayhem. Lots of failure of this kind in the USA.
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