步行街II:文件记录

上周的这个时候,我 考虑与步行街相关的常见问题 和 mentioned that 35-40kph (25mph) moves the most 交通. I didn’甚至在我写的时候都想不到。就像我脑子里长久以来所说的那样。物质实事求是地。

读者带我去做任务,想知道源头。

我不得不回顾我的城市设计论文,以发现实际上显示出来自多种来源的推论,并要记住预测和研究人类行为是一门社会科学。尚未提供27mph的确切参考,但这是让您进入社区的原理和一些辅助材料。

1.第一个来源是已在“交通工程”,以绘制平均行驶速度与总流量(每车道每小时每小时的车辆VPHPL)的图表。研究结果表明,在40mph时,您可获得约500VPHPL,在30mph时,您可获得约820VPHPL,而在10mph时则为1050VPHPL。可以看到的原因是,随着汽车加速,它们会散开。如图所示,该数据表明存在自由流动状态。

阿特卡普

2.中的第二张图 此运输政策帖子 creates a great rationale for 20mph speed limits being the future of urban transport. The graph, Figure 4, also plots predicted 交通 flow against speed. What’有趣的是,在20mph之后,每条车道的附加容量差异几乎没有,达到50mph。 25mph也很适合这里。

图4

3.这篇文章上线后,我又收到了一张图表— this one from the 运输研究委员会的公路通行能力手册”通过 社区建设者圣贝纳迪诺 —展示相似的现象并适应相似的速度范围。

公路通行能力

4. “大道书由Jacobs等人撰写。是必读…必须拥有的。他们的主要先例研究之一是位于加利福尼亚奇科的一条名为“滨海艺术中心”的街道。这是从城市出发的主要路线’s Downtown, a multiway 大道 built 在 the 1920s. Not only does it move lots of 交通 elegantly 和 efficiently at 25mph, it has desirable real estate —商业,单户住宅,多户住宅和学校— directly facing it. Now, when you go down a mile from the downtown, the street turns 在to an “arterial,” presumably carrying the same 交通 at 40 mph. The first thing you do is sit at a light with a bunch of other drivers amidst a 可怕,噩梦 郊区购物中心现场。它的街道比其哥哥(滨海艺术中心)更贵,其行为如此糟糕,以至于削弱了每个路口的财产价值和人类幸福感。现在,我不’我不需要一本书来告诉我’我曾经在这里工作过很多次,可以根据经验发言。

滨海艺术中心,加利福尼亚州奇科。

滨海艺术中心,加利福尼亚州奇科。

5. Intersections: So, we have determined that lower speeds can support comparable, if not more, vehicles per lane. Any 交通 engineer will tell you that actual capacity is really constrained at 在tersections. So here is the last piece of data. You can only fully realize the advantages of lower speeds 在 free-flow conditions. This only happens 在 two ways: 1. On high speed thoroughfares, which are not conducive to a walkable street environment; 和 2. Where you can time your lights. This is where 40mph more than fails… 在 that after your 40mph free flow, the light turns red 和 you sit through a light cycle. Once it turns green, the stacked cars slowly move forward, spreading out one 通过 one to reach 40mph+ just 在 time to hit the next light. In urban situations, with lots of 在tersections 和 on major thoroughfares, 和 at 25mph, you can effectively time the lights for a periodic free-flow condition for most hours of the day. This is how the Esplanade does it, 和 actually so do many downtowns throughout North America. And during peak hours, yes, they get congested. Just like 动脉s.

但是至少行人,自行车和公共交通仍然可以完成他们的任务。仅此一点就能解决问题。

杰夫·代尔

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评论

  1. 3. Roundabout, Blackson twist or other unsignalised, narrowed, direction-change-forcing 在tersection (see Poynton video). Rather than risking the start-stop of signals, just get rid of them, 和 design 在tersections as places where 交通 slows. Intersections are the hub of urbanism: unimpeded free-flow might even be as bad as idling bunches. Instead, make it clear that the pedestrian is king at 在tersections, cyclists princes 和 drivers 在vited at their whim. If no-one’周围,​​驾驶员可以减速并继续行驶;如果人们在交叉路口,她也可以放慢脚步,向后走,并在他们身后继续前进。

  2. 作为工程师,即使我喜欢图形和数字’m not a “traffic”工程师。作为经常骑自行车的人和步行者,我更关注观察到的结果。换句话说,如果没有’真的没有用’无论您如何得出技术结论。虽然我很希望看到许多道路降低到公布的时速限制为每小时25英里左右,但这可能不会发生,因为我行走和居住的大多数道路最近都增加到了45英里每小时,可以说是在密歇根州之前提高了速度’完整的街道立法全面生效。其中许多是仅在住宅,学校和教堂组成的居民区中的两条车道道路(或沿Chuck Marohn行驶的道路),但它们确实是其他区域之间公认的连接器。它们通常由县公路委员会和/或密歇根州交通部控制和维护。有些人行道或我们所说的惯例“safety paths” sometimes better known as shared use paths, but they are seldom used. So my question to the more learned people that probably read these posts is why 45+ m.p.h.? As noted 在 this 文章, it does little to move more cars, Lights 和 在tersecting 交通 conditions further reduce the actual average speed 和 交通 count, it certainly diminishes perceived comfort 和 safety for pedestrians but I highly doubt this is a goal especially 在 a school zone, at least I hope it isn’t。只是好奇是否有其他研究表明,汽车中的人想要以每小时45英里的速度行驶。无论位置或条件如何,这似乎都是我所处的新常态。为了什么’s worth, I can often get from my house to our small downtown faster 通过 bicycle as the cars often back up at the 交通 lights. I can often do better or equal than a car 通过 walking during high 交通 times. This is without any bike lane or special provisions 和 4 foot wide sidewalks 在 reasonably good conditon. It seems to me that this is a problem for both the motorist 和 pedestrian.

  3. I’在我的职业生涯的大部分时间里,我都看过所有这些图表,而问题是汽车以较高的速度彼此隔开。在通用车道上已经可靠地测量了22-2400 vphpl的高速公路通行量,而1800-1900 vphpl的吞吐量则基本上在自由流动条件下运行。这是因为自从完成原始分析以来,数十年来车辆间距已大大减小,并且高速公路上的驾驶员行为类似于赛车驾驶员,而不是避撞驾驶员。–驾驶员不是通过在发生事故之前能够完全停车来避免撞车,而是通过寻找并保留其他车道选项来避免撞车。根本不是’确实,本地街道可以与高速公路的吞吐量相提并论。

    话虽如此,我不’不想让任何人在高速公路上行走。知道在混合信号,交叉路口和行人时,通常以25-35 mph的速度获得最大的吞吐量确实可以证明我们都没有’不需要快速采取行动,但我们所有人都希望如此迅速采取行动,尤其是在一天中90%的时间都处于拥挤状态时。那里是高速设施的地方。这里有一个拥挤的调速设施。还有一些我的景观设计师朋友称之为的地方“tubes”–提供车辆或自行车连接的非场所“places.”知道从行人的角度来看,大于几平方英里的区域不在人的合理步行范围内,问题就变成了我们对所有其他区域怎么做?一世’我不是Stroads的拥护者,但是他们在土地产权领域的领先地位并不奇怪。

    • Stroads的问题是,任何旧企业都有权访问主拖动—到那时,您不再具有简化的高速公路风格的运动,而是获得了许多停车灯和冲突点。

  4. 嗨,我住在萨隆诺(意大利伦巴第),这是一个位于米兰,瓦雷泽和科莫(距离他们25-35公里)的小镇。如果我们将所有8个分类,这是第36个’000意大利城市人口密度(人口/ km ^ 2).. 3’每平方公里650名居民(总计40’000/12km^2) . The town has two highway exits 和 two train stations. For those motivations has an high level of 交通 congestion 和 the level of CO2 和 pullution is over the legal limits for months during the year. Two years ago the Mayor 在troduce a 30Km/h limit 在 the entire city without differences between areas, hours, citizens.. that limit has existed for about 6 months but then was substantialy eliminated. Why? It was really ridicolous when there was no 交通 to go at that speed 和 when there was 交通 the speed was already slow, slower than 30km/h. The penalties were seen impopular 和 many ilarious songs 和 posters about the policy. No effects on air pollution because the major problem were home’s emissions 和 交通 conjestion.. I have read UK reports saying that this policy was used for people security, to reduce crashes, not to reduce smog because emissions are lower at 80km/h. However thi story reveal that people are able to do collectively something really great 和 strange, even if impopular, if imposed. This is not to say to impose a 30km/h speed limit but to say that something more serious 和 useful, even if difficult to implement, can be made.

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