NOISE LEVELS IN ZONE 30 AFTER INTRODUCTION OF SEVERAL SPEED BUMPS

ABSTRACT

Zones 30 have been used for years in suburban districts as common traffic calming devices. The solution of zone 30 was used in a street in Szczecin. The street connects the area of detached houses with large panel housing estates. To reduce speed to 30 km/h, four successive raised areas were made of paving stone cubes as well as a 1 m wide median strip in the road axis. The change of asphalt blanket into paving stone cubes is thought to change the acoustic climate, due to differences of noise levels generated by traffic. The differences depend on a number of factors, including traffic volume, actual speeds and development of green areas in the neighbourhood of the street. The section of the street where a zone 30 was introduced is 800 m long. Traffic calming devices, including four raised areas posing vertical obstacles for motorists, were introduced along the length of the street at four crucial intersections with local and internal roads, leading to private premises, and public slip roads, leading to terraced houses. The raised areas were made of granite pavers and the sections in-between were covered with WMA (Warm Mix Asphalt). To confirm the hypothesis of increased levels of traffic noise at the interface of two surface types, the authors made several measurements of noise in the vicinity of the raised areas. The paper presents results of traffic noise distribution at the street with successive raised areas made of paving stone cubes.

Keywords: zone 30, noise level, acoustic climate, development of street neighborhood, raised areas