Driving quietly – sleeping soundly

Traffic experiment: 30 km/h at night: more noise protection on main roads

Project Profile

Project Title: „Traffic experiment 30 km/h at night on selected main roads“

Subject Cluster: Mobility

Project Objectives: Reducing noise on main roads, preventing health complaints, enhancing quality of life and residence; assessing whether a speed limit at night results in lower, relatively constant speeds and less noise pollution.

Project Duration: 2015–2016

Project Participants: Offices commissioned with the traffic experiment: LK Argus Kassel GmbH, LÄRMKONTOR GmbH, Messtechnik Mehl GmbH, shr moderation, Environment Office, Roads Department

Noise is not only harrowing it can also be detrimental to health, particularly when it disturbs people's sleep. Traffic is the main cause of noise, especially on main roads. The trial is intended to show whether a speed limit during the night lowers noise pollution.

Traffic noise disturbs sleep as it influences the depth of sleep and – depending on the acoustic pressure level – can cause people to wake up. This not only impairs the quality of life but, in the long run, can lead to health complaints. The noise thresholds in Frankfurt, particularly on the main roads passing through residential areas, are often exceeded by a large margin.

Frankfurt is examining in a trial whether lowering the speed limit at night is an effective noise abatement measure. The “30 km/h at night on selected main roads“ project is one element of the Regional Council in Darmstadt’s noise action plan and was stipulated in the framework of the noise abatement plan.

Back in 2012, the maximum permitted speed in Höhenstraße in Frankfurt Bornheim was lowered to 30 km/h between 10 pm and 6 am. This showed that at 30 km/h the overall noise level drops. Between 5am and 6am, a particularly critical time for the quality of sleep, it fell by as much as 4 dB(A).

A survey of the residents revealed that individual racers, motorbikes and lorries are particularly disturbing and that most people endorse the speed limit.

Second trial on four streets

As the findings are only transferable to a limited extent to other roads, Frankfurt is reviewing their effectiveness on four other road sections: the new trial was approved by the State Ministry of Transport for Nibelungenallee/Rothschildallee, the south section of Eschersheimer Landstraße, Untermainkai/Mainkai/Schöne Aussicht and Lange Straße

The test was accompanied by intensive public relations, information events and surveys of residents and road users. The findings available for 2015 confirmed that a 30 km/h limit in the night produced a sound level difference of   2.8 to 4.5 dB. Over three quarters of the residents surveyed think 30 km/h at night is, in the long term, beneficial and two thirds extremely beneficial.

In the second part of the trial from 25th April until 2nd May 2016 traffic counts and speed measurements were again carried out. These repeat measurements were to evaluate whether drivers had become familiar with the speed limit, if there had been a further reduction in the speed level and whether the traffic had found alternate routes.

The findings were made available at the end of 2016.

More information at: www.frankfurt.de/tempo30nachts

Reducing noise

The project assesses whether lowering the speed limit is an effective noise protection measure. The aim is to lower harmful traffic noise and keep it at a constant level. This would effectively reduce the severe fluctuations caused by individual racers which are often perceived as extremely debilitating.

Promoting human health

Reducing night-time noise to prevent waking up and compromising the essential regeneration of sleep; improving the quality of life with health-promoting measures.

Road Traffic Department

Nadja Lich

Tel +49 (0)69 212-44734