See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/11852558 Do speed bumps really decrease traffic speed? An Italian experience Article in Accident; Analysis and Prevention · October 2001 DOI: 10.1016/S0001-4575(00)00070-1 · Source: PubMed CITATIONS READS 90 1,084 2 authors, including: Massimiliano Pau Università degli studi di Cagliari 190 PUBLICATIONS 2,087 CITATIONS SEE PROFILE Some of the authors of this publication are also working on these related projects: EMG Characteristics of Gait in Healthy Aging and Parkinson's disease View project Well-being and successful aging in the Sardinian Blue Zone View project All content following this page was uploaded by Massimiliano Pau on 27 March 2018. The user has requested enhancement of the downloaded file. Accident Analysis and Prevention 33 (2001) 585– 597 www.elsevier.com/locate/aap Do speed bumps really decrease traffic speed? An Italian experience Massimiliano Pau *, Silvano Angius Department of Territorial Engineering, Transportation Section, Uni!ersity of Cagliari, Piazza d’Armi, 09123 Cagliari, Italy Received 2 March 2000; received in revised form 30 July 2000; accepted 31 July 2000 Abstract Italy introduced the extensive use of speed bumps only in 1990, in an attempt to limit the high number of fatalities involving pedestrians in urban streets caused by the high speed of vehicles. In many countries, such devices have been the subject of careful investigations (in order to assess their effectiveness and disadvantages for the traffic circulation) and this has resulted in a number of modifications in the design to improve their performance. On the contrary, no systematic and scientific studies have been carried out on Italian installations: moreover, the type of undulation adopted is known to produce a series of problems for some categories of users and is not so effective in reducing speed as larger devices such as ‘speed humps’ or ‘speed cushions’. This paper proposes a study of the effectiveness of 23 speed bumps installed in the city of Cagliari; to this aim, a speed analysis was performed at speed bump locations, at the crosswalks protected by the devices and at sections of the streets where bumps are installed but far from them. The results show that in one third of the cases the 85th percentile of speed measured at the speed bumps is higher than the posted speed limit (50 km/h) and an equal percentage of vehicles travel at a speed in the range of 45–50 km/h. No statistically significant differences were found from the comparison of speed values observed in free, bump or crosswalk sections of the same streets, while speed profiles calculated at four sites, where a high percentage of braking vehicles was observed, showed a common trend from which it clearly emerges that the effect of the device on driver’s behaviour is restricted to a short spatial range (about 20–30 m before and after the bump). The current situation thus suggests the use of more effective devices such as humps or cushions, or the integration of speed bumps with other traffic calming techniques. © 2001 Elsevier Science Ltd. All rights reserved. Keywords: Speed bumps; Pedestrian safety; Traffic calming 1. Introduction, background and purposes of the study Since early studies were carried out by the Transportation Research Laboratory (UK) in the 1970s (Watts, 1973), the use of vertical raisings of the road pavement as a passive method for controlling the speed of vehicles has become common in many countries (especially in western Europe and North America). To date, several kinds of these devices have been designed by exploiting the same basic principles, but with the obtaining of different results in terms of effectiveness, discomfort, and dangerousness for some categories of road users; usually they are classified as: * Corresponding author. Tel.: +39-070-6755270; fax: +39-0706755261. E-mail address: pau@doctorsun.unica.it (M. Pau). 1. Speed ‘‘bumps’’. 2. Speed ‘‘humps’’. 3. Speed ‘‘cushions’’. The first two are characterised by a continuous vertical deflection placed across the street made using several materials (rubber, concrete, thermoplastic materials etc.) but with a range of different dimensions. As shown in Fig. 1, speed bumps are very short (usually the width is between 600 and 1200 mm) with a height in the range of 30–100 mm (depending on the posted speed limit) and a circular or parabolic profile, while speed humps have about the same height values, but are wider (from 4000 to 8000 mm) and have a variety of different profiles (circular, sinusoidal, flat top etc.). From the viewpoint of the effect on vehicles, speed bumps produce impacts that are often dangerous for the suspension system and are a source of high levels of 0001-4575/01/$ - see front matter © 2001 Elsevier Science Ltd. All rights reserved. PII: S0001-4575(00)00070-1 View publication stats
