Background

The city of Zurich progressively pursuits a strategy of reducing road traffic noise by lowering the speed limit to 30 km/h on street sections that exceed the legal noise limits.

Aim of this study was to evaluate the effects of the reduced speed limit on noise levels (Lday and Lnight), noise annoyance, self-reported sleep disturbance, perceived road safety, and in particular, to elucidate if the reduced speed limit leads to a shift of exposure–response relationships towards lower effects.

Methods

We surveyed about 1300 randomly sampled inhabitants, in a repeated measures study, before and after the speed rule changeover from 50 km/h to 30 km/h along 15 city street sections, by postal questionnaire. Concurrently, individual noise exposure calculations based on traffic counts and on-site speed measurements were carried out before and after the changeover.

Results

Road traffic noise Leq's at the loudest façade point dropped by an average of 1.6 dB during day and 1.7 dB at night. A statistically significant decrease of noise annoyance and of self-reported sleep disturbances was observed, as well as a moderate but significant increase of perceived road safety. Most importantly, the exposure–response relationships for annoyance and sleep disturbance were shifted towards lower effects in the 30 km/h condition by, depending on receiver point, between about 2 dB and 4 dB during the day and about 4 dB at night, indicating lower effects at the same average level. This is a hint that, in addition to lower average exposure levels alone, other factors related to the lower driving speed additionally reduce noise annoyance and sleep disturbance.

Conclusions

City dwellers probably benefit from traffic speed reductions to a greater degree than would be expected from the reduction in average level attained by the lower driving speed alone.

中文翻译：

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将城市限速降至 30 公里/小时可减少噪音干扰并改变暴露-反应关系：来自苏黎世实地研究的证据

背景

苏黎世市通过将超过法定噪声限值的路段限速降至 30 公里/小时，逐步推行减少道路交通噪声的战略。

本研究的目的是评估降低限速对噪音水平（Lday 和 Lnight）、噪音烦恼、自我报告的睡眠障碍、感知道路安全的影响，特别是阐明降低限速是否会导致暴露-反应关系向较低影响的转变。

方法

在一项重复测量研究中，我们通过邮寄问卷调查了大约 1300 名随机抽样的居民，在速度规则从 50 公里/小时变为 30 公里/小时的 15 个城市街道路段前后。同时，在转换前后进行了基于流量计数和现场速度测量的个人噪声暴露计算。

结果

最响亮立面点的道路交通噪声 Leq 在白天平均下降 1.6 分贝，在夜间平均下降 1.7 分贝。观察到噪音烦扰和自我报告的睡眠障碍在统计学上显着减少，以及感知到的道路安全性适度但显着增加。最重要的是，在 30 公里/小时的条件下，烦恼和睡眠障碍的暴露-反应关系向较低的影响方向移动，具体取决于接收点，白天大约 2 分贝到 4 分贝，晚上大约 4 分贝，表明在相同的平均水平下效果较低。这暗示，除了单独降低平均暴露水平外，与较低驾驶速度相关的其他因素还可以减少噪音干扰和睡眠障碍。

结论

城市居民从交通速度降低中获益的程度可能比仅通过降低行驶速度所达到的平均水平降低所预期的更大程度。