Technical Note Advancement of three-dimensional noise mapping in Hong Kong Chi-wing Law a,⇑ , Chee-kwan Lee a , Aaron Shiu-wai Lui a , Maurice Kwok-leung Yeung a , Kin-che Lam b a Environmental Protection Department, The Government of the Hong Kong Special Administrative Region, People’s Republic of China, 26th Floor, Southorn Centre, 130 Hennessy Road, Wanchai, Hong Kong b Department of Geography and Resource Management, The Chinese University of Hong Kong, Shatin, NT, Hong Kong article info Article history: Available online 5 March 2011 Keywords: Environmental impact assessment Road traffic noise assessment 3D noise mapping Public consultation abstract The dramatic enhancement of computation power, rapid development in Geographic Information System (GIS), three-dimensional (3D) computer graphic and virtual reality technology; and the wide availability of digital topographic and mapping data have facilitated the substantial advancement in road traffic noise assessments and data presentation in Hong Kong. Two-dimensional (2D) and even 3D noise mapping over a large geographical area has now become a more manageable task. In Hong Kong, very often roads are in close proximity to the sky-scrapers and 2D noise mappings are simply inadequate in accurately portraying the noise exposure environment. Traditional commercially available noise modelling tools are incapable of handling the complex topography, building geometry and noise screening structures of Hong Kong. 3D presentation tools integrating noise modelling, GIS and computer graphics are needed to portray the noise environment in the unique high-rise townscape of Hong Kong. This paper outlines the development of advanced 3D GIS tools, information technologies and how they were put into trials and implementation in Hong Kong. Particular attention is given to the dissemination of noise information to the community, be it for public education, engagement or consultation; and recent advances in the availability of such information interactively, and in a user-friendly manner, through the internet. Ó 2011 Elsevier Ltd. All rights reserved. 1. Introduction Like other metropolitan cities, road traffic noise is one of the prevalent environmental problems in Hong Kong. Due to insuffi- cient flat land and rapid development in the past, very dense and compact built-environment has been resulted. Rapid economic growth in the past two to three decades has meant more new developments and more traffic in very limited areas, resulting in serious noise problems. The topography of Hong Kong is characterized by steep hill- slopes with limited flat land. Only about 25% of the area has been built up for urban development; and another 40% of the land area is designated as Country Parks and Nature Reserves [1]. The vehicle density in term of vehicles is about 283 per km road in 2009 [2], which is one of the highest among the developed economies such as Germany and UK. Moreover, Hong Kong is unique in the sense that it is the most densely populated city in the world, with numer- ous 40, 50 or even 60 storeys high-rise residential buildings in a densely packed and compact environment. In such as complex urbanscape, the noise exposure pattern at the building facades is extremely complicated. To facilitate a better understanding of the road traffic noise problem in Hong Kong, setting objectives and developing plans to address the issue, the latest Geographic Information System (GIS) and large-scale noise modelling technologies have been used to collate and compile the required noise information – identifying and quantifying the scale of noise problems and evaluating the effectiveness of the mitigation measures for road traffic noise. With the help of much faster computers nowadays and avail- able digital land information in GIS, in year 2002, the Environmen- tal Protection Department (EPD) of the Government of the Hong Kong Special Administrative Region (HKSAR) started to prepare a territory-wide noise contour map for Hong Kong [3,4]. By means of a map, with simple colour contours, the noise information could be presented and more easily understood by the public as com- pared with the traditional presentation using maps and table for- mats. A typical noise contour map is shown in Fig. 1. This map indicates the road traffic noise assessment at 4 m above ground as recommended in the EU Directive [5]. Colour grids of noise lev- els, buildings, podiums and road centre lines were also presented. Moreover, through the GIS and available statistical information, useful information such as population exposure to road traffic noise in each district could be approximately estimated, as shown in Fig. 2 by several of two-dimensional (2D) noise exposure maps at four different heights [3,4] used to illustrate and present the noise exposure of population. Nonetheless, the information 0003-682X/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.apacoust.2011.02.003 ⇑ Corresponding author. Tel.: +852 2835 1257; fax: +852 2802 4511. E-mail address: cwlaw@epd.gov.hk (C.-w. Law). Applied Acoustics 72 (2011) 534–543 Contents lists available at ScienceDirect Applied Acoustics journal homepage: www.elsevier.com/locate/apacoust