孤独的怪兽: 六月 2009

在DailyTech上看到了这个，MIT校内的链接在这里http://web.mit.edu/newsoffice/2009/traffic-0609.html。

基本思想：无明显原因的交通拥堵（phantom traffic jam），起因应该是人类在非常拥堵的交通中驾驶的一点点扰动，如加速或刹车，会迅速放大，引起交通拥堵。MIT的数学家们建立了一个模型，可以揭示这种拥堵，在何种条件下，是如何产生的。

去年日本Nagoya大学的研究者已经通过实际验证了这一类拥堵的产生。在Youtube上的NewScientist频道。

具体研究没看到论文不便评价，不过比较有意思的是DailyTech上的评论，摘录一些并翻译如下：

Large population centers + people going to work + roads not being large enough + stupid drivers who get in accidents or tie up lanes because they try to move from the far left lane to the far right lane for their exit at the last second = traffic jams

交通拥堵 = 人口众多 + 集中上班 + 道路不够 + SB的driver总是在最后时刻才换道

Oh I forgot stupid people who feel the need to slow down to 5 mph to gawk at said accidents.

哦，还有就是把车速降低到5mile的看交通事故的人

Seriously. Those are the people that cause rear ended accidents. Not to mention people who try to merge into traffic at 70+ with a space barely big enough to parallel park their car.

最主要的就是会车的时候，ramp上的车硬往车队里挤。

True. One of the basic laws of physics is the speed of a car is less than or equal to that of the car in front.

As the density of cars on any given road goes up, the cushion between cars gets smaller. Since a car cannot travel faster than the car in front, when the car in front brakes or misses a gear change, the car behind must brake equal to or greater than the car in front.

As the average gap between cars gets smaller, so the need to brake harder than the car in front goes up. These two factors (speed car behind <= car in front, braking car behind >= braking car front) causes speed oscillations, which is really just classical wave theory. As with a normal amplifier, where the amplifying device cannot exceed its power supply's capability, so the traffic problems really start to happen when the physical bounds of the environment (speed limit or grinding to a halt) are approached.

This is why you get congestion around areas with merging traffic, because cars merging into a dense traffic stream with no extra lanes is just like an impedance mismatch. If the merging stream is also dense then really the only way to fix it without causing congestion is to have the merging traffic have their own lane.

However, it is important to note that if a line of cars is long enough, as happened when they were evacuating New Orleans, then you will get vehicle speeds that oscillate, which will cause vehicles to grind to a halt for no apparent reason.

随着车的增加，车头间距在减小，车头间距的减小，使得人们在加速或刹车时要采取更大的动作，也就是使得整个车队的速度震荡更加剧烈。从车队头到车队尾，振荡的剧烈程度逐渐递增。当车辆妄图在拥堵路段merging时，就像电路里的阻抗不匹配（impedance mismatch）。唯一的解决办法也许就是为汇入的车流单独设立一个车道。值得注意的是，像从New Orleans逃离时的庞大车队一样，当车队足够长，车速将剧烈振荡，车辆可能不因为什么就突然刹车。

People driving fast, slow, lots of people all leaving for work and leaving work at the same time. Solved! I'm in Taiwan right now(live in Portland,OR) and must say that USA traffic jams are shocking. Taiwan has smaller roads, and a whole lot more people on them, the difference is that they have a crap ton of motorcycles and scooters. The scooters travel in something similar to bike lanes in the states, and are allowed to split lanes. So what I'm trying to say is that here traffic jams are less severe even though the roads are much smaller, plus the cities are super dense so work is usually somewhat close to home, and commuter rail comes every 10-15 minutes. Its all about options, more modes of transport means its less likely to have horrendous traffic jams.

在台湾我们人口更多，且道路更窄，但交通问题并不像美国那么严重。因为我们有单独划出来给摩托车和电动车的车道，还有每10分钟1趟的轻轨铁路。所以，当交通模式的选择更多时，发生拥堵的概率就越小。

The source of many problems is that people see traffic as "A bunch of independent cars" instead of looking at it as one "organic" form.

Like cells and organs in a human body, every car affects the whole organic body of traffic, and if these cells or organs start shitting all over each other, the whole body will suffer as a result.

If the heart suddenly decided that "Fuck you brain, I'm not going to pump blood up to your lazy ass anymore!", things will soon be going south for the heart as well, same with assholes in traffic, they're just too stupid to realize it.

因为我们在看待交通问题是更多的是将其看作一大堆独立的车辆，而不是一个有机的整体。

Im not sure how it is in the US, but here in australia on the freeways there are LED signs that light up during peak hours in order to take advantage of this fluid dynamics.

eg. speed is reduced to reduce stop start.

Only problem is, humans are greedy/inconsiderate and many ignore the speed sign anyways only to stop 3 cars in front and ruin the fluid dynamics model.

I always love hearing how people complain WHY speed limits are reduced when its peak hour rather than sped up. lol.

在澳洲，在拥堵时段，我们的高速路会有LED灯提示减速，以使得刹车和启动平稳。

最本质的问题是人类的贪婪！

Studies have shown that accidents are more likely to happen at lower speeds than at higher speeds. That is also why we have minimum speed limits on freeways.

No matter which way you look at it, its better to stay with traffic, even if that means speeding. When I lived in Chicago, the speed limit was 60, but if you were not doing 80 then you had people 6" from your rear bumper blasting the horn. In that case, the slow driver is the danger because 90% of the cars are going over the limit. Staying with traffic is safer, causes less congestion, and gets you where you need to go faster.

研究发现，相比高速时，低速时更容易引发交通事故，所以我们的高速公路都有最低限速。

不管怎么看，最好的方法是与车队中的其他车辆速度保持一致，即使这意味着加速。在我住在Chicago时，限速是60，但如果你不开到80，你的后面6inch远就会有人按喇叭。在那种情况下，低速的司机是危险的。

True to that. It is not speed, but variations in speed that cause density waves. The people who go slow force other people to go around them, which forces people in the other lanes to slow and try to go around further, which forces etc. Density wave.

确实如此。并不是速度高低引起了拥堵波，而是速度的不一致性。当一个车道上的某人速度慢时，他后面的人不得不超过他，势必要进行换道，又会引起周围车道的车辆减速。于是，交通拥堵波就产生了。

That doesn't compute. The higher the speed the more cars per second a roadway can hanlde. Lower speed = fewer cars per second = more traffic.

高速代表更多的车在单位时间被处理，低速正好相反。

The more cars on the road, the more cautious and overcorrecting the drivers become, and the slower the traffic. The net affect is that the roadway can handle lower car counts at higher speeds, and higher car counts at lower speeds. Its called Rush Hour.

更多的车在道路上，会使得驾驶员更加专心注意和遵守法规，使得速度更慢。高速时，车辆少；低速时，车辆多。

not really true. At high speeds, the headway increases, and you while your vehicles are travelling faster, there is more space needed between them.

2400 vehicles per hour per lane is about the maximum theoretical capacity of a freeway lane. This volume gets reduced by a host of factors, including:

Truck percentage

driver familiarity

Interchange spacing

lateral clearance

lane width

just to name a few.

教科书式说法：车道容量与以上因素有关。

I've often wondered how traffic can come to a full stop when there are no stop signs or streetlights and no cross roads to turn off onto.

The biggest reason is too many cars getting on and off the exits close to the same time. The exit ramps are notoriously too short, and the entrance ramps usually merge onto traffic way too soon.

I wish they'd create a wall for a half mile before the exit so people cannot merge at the last second, and a wall at the entrance for at least half mile that splits into two lanes before it can merge with traffic. This won't solve all the problems, but i'm sure it would help.

Some might say its a danger putting a wall there because someone might hit it...but if they hit the wall at the merge/split...then its one less driver we have causing traffic jams! :)

最大的问题是太多车希望在同一时刻进入或退出告诉公路。最好的办法是修一堵很长的墙，使得想退出的车辆不可能在最后一刻才换道。在入口处车先开半英里再汇入高速路。有人会说有墙不太安全，有人可能会撞上墙。不过我觉得，如果那样，我们不是又少了一个可以制造交通拥堵的糟糕司机？

Environuts might even support that since they think we're a cancer on the planet.

我们是这个星球上的癌症。

I read a study a while ago regarding the impact of adaptive cruise control on traffic congestion, and the authors determined that if only 20% of cars utilized it, then traffic congestions would be cut in half.

These are cruise control systems that will slowdown automatically if another car is in the way, then accelerate again when if moves.

It’s funny how governments focus on MPG, biofuels, and expensive hybrid technology as a solution for our environmental problems – but if they simply mandated an existing and (somewhat) cheap technology be installed in every car we could reap benefits far in excess of these solutions.

我以前看过一个自适应巡航控制的研究，如果20%的车用了这个控制，那么交通拥堵会减少一半。

我们的政府目前重点搞生物燃料、混合动力，实在是搞笑。

3D is needed.

It won't come before proper electrogravimetrics techniques arrive.

Sure, you can alleviate some problems with bridges and underpasses (2-D routes) and perhaps solve this with variable speed limits that traffic controllers impose, but with traffic forever growing, its pissing into the wind.

飞行的交通工具将解决这个问题！

Rubber-necking at accidents on the opposite side of the road seem to cause most of the senseless traffic jams. If you can change human nature or allow computer-driven vehicles on the road, that'll take care of the problem.

Otherwise, we're just going to spend an enormous amount of tax-payer dollars to find out the hard way, that you just can't fix stupid.

对向车道看热闹的人引起了最多无意义的交通堵塞。如果能改变人性或者使电脑驾车，问题就解决了。

另一方面，我们可以每年花纳税人那么多钱去找到最拥堵的路段，但是不能改变人性的愚蠢。

We've been doing that for decades....but look at this year alone! Bailouts, stimu...i mean "pork-ulus" bills, and a wealth of social programs like the recent "studying how gays react in South American bars" and "how to help hookers in China".

They don't fix anything, they just show how stupid our elected officials really are - and they think the masses are stupid.

我们这么做已经很多年了。看看他们的社科研究项目吧，如何帮助中国妓女，南美酒吧里的同性恋如何沟通。

他们不能解决任何问题，他们只是展示了我们所选的官员们有多么愚蠢！

Yay, overpoliticized comments on every article!

每篇文章都会有政治评论（愤青无处不在啊）

I work in a different state than where I live so I see plenty of bad driving.

Here are some of the most frustrating and most common issues (in fact I'm sure I'll see them today!):

1) Frequent lane changes in heavy traffic. A lane change for a reason , like coming up to your exit or because the lane ahead is blocked by an accident is fine....but when ALL lanes are moving 5 mph why on earth do some folks insist on changing lanes every 5 minutes?

2) The can't make up his mind type. You've been behind this person before I sure --- he's driving 10 mph under the speed limit when you are behind him then when you go to make your move to pass he suddenly speeds up to match your speed, so you think ok I'll stay here then -- you stay there and now the guy's back down to just at the speed limit or below it again. It might be an amusing game to you -- if you do this, but I just was trapped in an office for 10 hours, I'm tired and I'm hungry and I'd like to get home you selfish prick....

3) What lane is my lane again? I see this more and more frequently -- folks that look like they are drunk, tires skirting along the lines in the road that divide up the lanes, some times dipping into one lane a few inches and then going back into another. This is annoying as hell --- first don't drink and drive and second if you are too stupid to figure out what lane you should be in, you really need to burn your license...like now.

4) The cheaters. Folks stacking up on the shoulder because they are too good to wait for their exit like the rest of us, meanwhile I'm thinking "that would really suck if an emergency happened right now with no shoulder available".

Also in this group are the line butters.....often on my final exit before my house the line to the exit is about a mile or two long -- sometimes someone will drive by on and squeeze into the front of the line. These people should be drug from their cars and beat to death. Apparently they think they are better than the rest of us and only their time is important not ours.

5) People who don't know how merge/exit a highway properly. I've seen folks come to dead stops as if a red light was at the ramp and then they try merging, I've seen people ride the full length of the "merge lane" even when they have plenty of time to get over before the merge....and i've seen jack asses speed out like a bat out of hell to merge at the same time I'm driving by and I nearly have to lock up my brakes to make sure I don't hit him because there was no sign of him coming when I passed the point of the exit.

I generally curse up a storm to myself every night I'm caught in traffic. So yeah MIT or whoever -- please improve this traffic situation. :)

我工作和居住不在同一个州，于是我看到了太多不好的驾驶行为。

1.频繁换道

2.前面的车在你超车时突然加速

3.不知道自己属于那条车道

4.开车开到路肩上去

5.不知道如何汇入和退出高速路的人

Up the Driving test requirements by 500%, Im SURE there will be A LOT less traffic problems.

把交通考试难度提高5倍。

http://trafficwaves.org/

You can stop a traffic jam by going much slower than the car in front of you, if the car in front of you stops you may not need to stop which prevents the cars behind you from needing to stop. Stopping increases total travel time.

开车比前车慢也许会阻止一场拥堵的产生，因为你和你后面的车都避免了频繁的停车和启动。

There is no mystery as to why traffic jams occur in places where there are no contruction/accidents. The road designs are bad, the people driving the cars aren't always paying attention, and the speed limits are way too low. I didn't even need a research grant for that, though I guess I would like one.

It's idiots like this at MIT who make me glad I paid half as much for my engineering degree at a state school. I got a job doing real work instead of staying in grad school for 10 years wasting my life.

研究结果是显而易见的。像这个MIT的白痴一样的人让我觉得很高兴，因为我在州立大学只花了一半的钱就拿到学位。我现在找到了一份工作，干实际的事情，而不是在一个研究生院里花上10年浪费我的生命。

Privatize the damn roads!

The product that private road owners would be selling is drive quality -- if you are sitting on a road for an hour whose trip time at road speed is actually 10 minutes then you are basically selling nothing. It is the fact that there is a government monopoly on roads that leads to the chronic shortage of road capacity -- how come things in the private sector never suffer permanent chronic shortages like this?

And smarmy sneering cynical economics professors tell us that the government has to create government owned or controlled monopolies on "natural monopoly" resources like roads in order to... wait for it... protect us from what they claim would be the "natural monopolies" that would arise in the private sector.

Echoes of the EU saying they have to remove the web browser from Windows so consumers are protected and given choice.

GOVERNMENT OUT OF THE ECONOMY!!!!

私有化这些该死的道路！！！

The lack of the ability of critical thought, the source of so many of our national problems.

我们国家这么多问题的来源，就是缺乏一种严谨思考的能力！

发信人: RealShrek (燃烧吧，小宇宙！), 信区: NewExpress
标题: 教育的失败 zz
发信站: 水木社区 (Mon Jun 8 13:17:55 2009), 站内

http://www.ohehlium.com/journal/2009/06/07/620/

教育的重要,无论是之于国家还是之于个人,都毋庸赘述. 中国的教育有数千年的历史,
其中几经变迁.最近的一次变革是文革以后以高考为核心的教育制度. 现行的教育体系从
八十年代初建立到现在,历经近三十年,已经渗透到中国社会生活的各个方面. 我在这个
体系中浸润多年,而后工作,再有机会到美国体验不同的教育体系. 其间不由得不对自己
从前的经历有所反思,有一些想法总是如鲠在喉,不吐不快.

总的来说,我们现在的教育制度是一个失败的教育制度.说它失败,是因为它没有达成现代
教育的基本目的.说到这里,就不能不说说教育的根本目的是什么.蔡元培先生认为 ”教
育者，养成人格之事业也”. 英国教育家Herbert Spencer在他的《教育论》中提出教育
应该“为完满生活做准备”。而Thomas Jefferson的说法是“To enable (a citizen)…
to observe with intelligence and faithfulness all the social relations unde
r which he shall be placed”。总结起来教育的意义有两层，一层是为了让受教育者
生活幸福而进行的人格培养，另一层则是为了受教育者成为合格的现代社会公民做准备
。我们的教育在这两个方面都是失败的。

我们的教育没有教给学生如何生活的更幸福。现代社会里一个人的生活有三个主要的方
面：家庭，事业，朋友（社交圈）。

家庭和睦很大程度上取决于是否能够找到合适的伴侣。不可思议的是，我们绝大多数的
学校和家长们似乎相信，建立家庭的能力类似于做爱，是不用教就自然会的。这里面的
误解至少有两层。其一，人是复杂的社会动物。寻找真爱要求我们真正的了解自己，并
且知道如何去了解异性，与异性相处。正确的指引和不断的尝试对于掌握该项技能是至
关重要的。其二，性其实也不是自然就会的… 我们的学校和家长们对于恋爱一不提供指
导，二不允许尝试，其结果就是广大同学从以下渠道自发的进行学习并且被误导：三级
片（含毛片）和言情小说（含言情电视）。当然，在学校和家长的悉心督导下还是有部
分同学到毕业时还没有受到两者的毒害。但考虑到这些同学毕业时的年龄，我认为这其
实更可怕…

再说说事业。我们需要认识到一个基本的事实：在学校学到的知识90%是在实际工作中用
不到的。有过工作经验的同学应该都同：沟通能力，自主能力和与人合作的能力对一个
人长期事业发展的影响要远大于知识或者技能。而我们的教育恰恰是在削弱这些能力。
我们的考试选拔制度决定了在学习过程中同学之间是不需要沟通与合作的，在很多时候
，过度竞争反而使得同学之间刻意避免有意义的沟通与合作，—第一名只有一个，帮了
别人就等于害了自己。在我们的教育体系下学习都是被动的。正确答案只有一个，最有
效的方法就是背过答案，讨论是没有意义的。学生学什么，怎么学，甚至怎么想都是被
严格限定好的。其结果就是，当这些条框随着我们走上社会而消失后，同学们不会自主
的安排自己的职业发展，不懂得如何做出选择，甚至不懂得如何学习，因为不懂得如何
问问题。

最后说说社交。我们的教育，尤其是在大学之前，是不给学生提供练习社交能力的机会
的。当身边的人都是你的敌人的时候，人又怎么能学会沟通与信任呢？

我们的教育不但没有教给学生如何幸福的生活，而且没有把我们塑造成合格的社会公民
。现代社会要求一个公民至少学会做两件事情，一是能够建设性的参与到社会活动中去
，这是民主的基础；一是能够用理性的态度去分析和讨论问题，这是科学的基础。在我
们的教育中，学生都是被动的被告知什么是对的，而没有一个自己思考的过程。所以我
们都被训练的倾向于相信权威，而没有自己的思索。而当一个社会的绝大多数人没有独
立思索的能力，而用情感或者传统作为判断的依据的时候，民众就容易被煽动。一个社
会即使有民主的体制，也不会有民主的实质；即使有科学的研究，也不会有科学的态度
。

教育是国家和社会发展的根本。中国现行的教育制度，如果不进行大的改革，会使得一
代人失去竞争力，这是一件让人担心的事情。

--

※ 来源:・水木社区 newsmth.net・[FROM: 59.66.120.*]

孤独的怪兽

2009年6月22日星期一

朋友的川藏线

2009年6月20日星期六

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MIT的交通新理论

2009年6月8日星期一

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2009年6月7日星期日

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