A large-scale study of the social response to construction noise in Hong Kong Silver C.K. Chan 1 Environmental Protection Department 26/F, Southorn Centre, 130 Hennessy Road, Wan Chai, Hong Kong K.C. Lam 2 Department of Geography and Resource Management, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong C.L. Wong 3 Environmental Protection Department 26/F, Southorn Centre, 130 Hennessy Road, Wan Chai, Hong Kong Richard Kwan 4 Wilson Acoustics Limited Unit 601, 6/F, Block A, Shatin Industrial Centre, 5-7 Yuen Shun Circuit, Shatin, N.T., Hong Kong. Wilson Ho 5 Wilson Acoustics Limited Unit 601, 6/F, Block A, Shatin Industrial Centre, 5-7 Yuen Shun Circuit, Shatin, N.T., Hong Kong. Morgan Cheng 6 Wilson Acoustics Limited Unit 601, 6/F, Block A, Shatin Industrial Centre, 5-7 Yuen Shun Circuit, Shatin, N.T., Hong Kong. Max Yiu 7 Wilson Acoustics Limited Unit 601, 6/F, Block A, Shatin Industrial Centre, 5-7 Yuen Shun Circuit, Shatin, N.T., Hong Kong.

1 silverckchan@epd.gov.hk 2 kinchelam@cuhk.edu.hk 3 clwong@epd.gov.hk 4 richard.kwan@wal.hk 5 who@wal.hk 6 mcheng@wal.hk 7 max.yiu@wal2.hk

ABSTRACT Construction noise is an issue in many large cities with potential annoyance and disturbance effects. With an aim to providing necessary data for formulating noise control and management strategies, a large-scale social survey was commissioned in Hong Kong and undertaken by a team of acoustic experts in 2018-2020. Based on the interview of around 5,000 randomly selected households following the ISO standard on 11-point numeric scale (ISO/TS 15666, 2003), this was one of the few large-scale studies carried out in a dense and compact city. This paper describes the rationale and approach of the study, the sampling and questionnaire design. Some of the key study findings are presented, highlighting in particular the prevalence and nature of construction and domestic renovation noise; annoyance and sleeping response of the respondents that would be useful for developing construction noise management strategies in Hong Kong. 1. INTRODUCTION

Surveys and studies on community attitudes to the environment in Hong Kong began in the early 90’s. However, there were no large scale survey conducted on environmental noise until in 1998, when the first territory-wide community survey was carried out with 2,000 successful telephone interviews [1]. It was found that among all noise sources the most annoying one was “traffic noise”, followed by “construction noise”, “aircraft noise”, and “neighbourhood noise”. Another large scale survey was conducted in 2010 through face-to-face interviews with 10,077 households [2], with a structured methodology based on ISO/TS 15666 – 2003 [3] for assessing the level of annoyance experienced by the interviewees. That survey revealed that “renovation noise” was ranked top in terms of % respondents highly annoyed, followed by “traffic noise”, “neighbourhood noise” and “construction noise” among other types of noise. This phenomenon could be explained by the relocation of the Hong Kong Airport from the city centre to the outlying Chek Lap Kok island (which had removed the aircraft noise footprint from the populated areas), and the blooming property market (which had increased the noise disturbance from domestic flats being renovated in high-rise residential buildings) since the economic turnaround in late 2003. In 2018, a city-wide survey involving 5,066 households was specifically conducted for studying residents’ attitudes towards construction noise and domestic renovation noise [4] with a similar methodology for noise annoyance assessment and a questionnaire design that probe more into non-acoustical factors that might correlate with people’s attitudes. A generally consistent social response pattern was observed, with “renovation noise” being ranked top in the list of highly annoying noise sources, followed by “traffic noise” and “construction noise”. Both infrastructure and residential developments were still very active in Hong Kong during the past few decades. The survey findings have been found useful for developing further management strategies for managing construction noise (including general construction site noise, and domestic renovation noise) in Hong Kong.

2. SAMPLING METHODOLOGIES AND QUESTIONNAIRE DESIGN

2.1. Sampling Methodologies

The survey covered the land-based non-institutional population aged 18 and over of Hong Kong. It did not cover hotel transients, inmates of institutions, and persons living on board vessels. The sample was selected from the database of all permanent and temporary structures in Hong Kong [5] in accordance with a scientifically designed sampling scheme. All households in the sample were approached for interview. A total of 5,066 households were successfully enumerated. Within each of these 5,066 households, a household member aged 18 and over was randomly selected by Kish grid method for interview.

Survey data were collected through face-to-face interviews during household visits. To test and ascertain the practicability of the questionnaire and related operational procedures, a pilot survey was

conducted with 50 households through face-to-face interviews. Considering the responses from the surveyed households as well as feedback from the survey team (fieldwork manager, supervisors, and enumerators), amendments for fine tuning purposes were made to the questionnaire.

As a result, a total of 6,669 households were found in the sample of 6,622 occupied quarters. In the 6,669 households, 5,962 households were successfully contacted. Among them, 5,066 were successfully enumerated while 896 did not respond. The response rate was 76%, which was satisfactory and similar to that of the survey conducted in 2010.

2.2. Questionnaire Design

All the survey was conducted via tablet with the data uploaded directly into the database to eliminate human error during data entry. Verification after survey enumeration were conducted for 1158 out of 5066 to ensure data consistency. There are 3 primary objectives of the social survey, as discussed in the ensuing paragraphs, to gauge people’s thoughts, views, attitudes and experience associated with noise from domestic renovation works and other construction activities. Design of the questionnaire is such that those objectives could be achieved by collecting as much information as possible while avoiding too excessive or tedious questions to be asked within a limited period of interview time. 2.2.1 Assessment of environmental noise induced annoyance caused by various noise sources

While the questions for assessing the perceived degree of noise annoyance were phrased according to the ISO/TS 15666:2003, this document was revised in 2021 after being in operation for nearly 20 years. The survey, though conducted in 2018-2019, had already incorporated some new elements as contained in the revised specifications. Two sets of noise reaction questions, i.e. 5-point verbal question and 11-point numeric question were used in the survey to ensure the psychometrical robustness, reliability and comparability, although the requirement that both questions should be asked was relaxed. Questions are designed to address annoyance over the whole 24-hour period during the last 12 months or so in locations in and around the home. Chinese wordings for questions on annoyance are equivalent to Annex B of ISO/TS 15666:2021 to accomplish accurate translations that would have the same meaning in each country allowing for further comparative studies. 2.2.2 Noise impact and responses to the impact

In order to understand more about the noise effects from domestic renovation works and other construction activities, a series of questions was designed to allow a description of the noise characteristics and how the noise annoyance had affected people. Information was also collected as to how people had tolerated noise or reacted to noise, including their actions or measures taken, channel(s) adopted, etc. 2.2.3 General living environment and factors related to tackling or managing noise problems

The survey also attempted to explore the living pattern of respondents and the role or advantage of property management in resolving noise problems and the prospect of certain administrative measures that could play a part in minimizing the noise disturbance. In particular, since one having been affected by renovation noise from a neighbouring flat might also renovate one’s own flat and disturb others, questions were designed to gauge people’s experience in renovating own flats and their willingness to pay for reducing the noise impact to their neighbours.

3. KEY STUDY FINDINGS

3.1. Public Response

In accordance with ISO/TS 15666:2003, interviewees were asked to scale their responses from 0 to 10 regarding different types of environmental noises, including noises from general construction and domestic renovation, where 0 was not at all annoyed and 10 was extremely annoyed. As regards the 0 to 10 numerical scale, reference had been made to the approximations on annoyance distributions analyzed with an exposure-response model [6]. Different categories of responses were adopted for facilitating the interpretation of the numerical scale, by denoting the upper scores of 8, 9 and 10 as “highly annoyed”, while the scores of 4, 5, 6, 7 were interpreted as “annoyed”; the scores of 1, 2, 3 were interpreted as “slightly annoyed” and 0 was interpreted as “not annoyed”.

70% 5 50% 3 ae Bax am 1 ° Not ‘Annoyed/ Not Heard Such Noise PERCEIVED NOISE ANNOYANCE LEVEL 1 2 Slightly Annoyed a 4 s 6 Annoyed Scale of Annoyance ‘m Domestic Renovation General Construction Highy Annoyed

It can be observed from Figure 1 that in the past 10 years less than half of the respondents were annoyed by construction noise and more than half of the respondents were annoyed by domestic renovation noise, to different extent. Interestingly, while about 7% and 14% of the respondents were highly annoyed by general construction works and domestic renovation works respectively, merely of a low proportion did the affected respondents lodge complaints, i.e. 4% for general construction noise and 8% for domestic renovation works.

Slightly Annoyed

Highly Annoyed

Not

Annoyed

Figure 1: Annoyance Response from Domestic Renovation and General Construction

With implementation of the Noise Control Ordinance (NCO) [6] in 1989 and the Environmental Impact Assessment Ordinance (EIAO) [7] in 1998 respectively in Hong Kong, legislative frameworks have been in place to protect residents against excessive exposure of construction noise. The use of Powered Mechanical Equipment (PME) for carrying out construction work including domestic renovation during the restricted hours (i.e. 19:00 to 07:00 during normal weekdays and anytime on a general holidays) is subject to the control of the Construction Noise Permit (CNP) system under the NCO; noise from construction work of major infrastructural projects during the non-restricted hours is subject to the control and monitoring requirements under the EIAO. Although much effort has gone into preventing noise, the survey findings gave insights on more efforts to further alleviate the noise impact to address the growing public demand for a tranquil living environment.

3.2. General Construction Noise 3.2.1 District Characteristics

High annoyance from noisy works such as percussive piling, general construction, demolition, road maintenance and domestic renovation were expressed by respondents living in all 18 districts, mainly in densely populated urban areas, which is understandable as such activities were normally conducted for facilities to serve communities around. Figure 2 illustrates the distribution of respondents of this survey geographically. Because noise from construction sites and domestic renovation is transient in nature, this distribution should not be interpreted as an illustration of noisy districts. However, it somehow reflects some major infrastructural projects or their associated developments having been or being carried out in certain areas that might have caused particular annoyance to the residents around the time when the survey was conducted, e.g. Shatin Central Link (a new railway that stretches from the New Territories all the way through Kowloon to the Hong Kong Island), Kai Tak development (a huge and complex development spanning over 320 hectares), and various housing projects over the territory.

FEHB Fe Boundary Plan of District Lands Offices

Highly annoyed by percussive ping Highy annoyed by genera eostctn Mihi annoyed by ceolion 2 High aay oad maenace iain aiiched Geaaeaee ana

Figure 2: Distribution of respondents highly annoyed by various noisy works in Hong Kong. 3.2.2 Types of Noisy Construction Works

Of more than 48% respondents who were annoyed to various extent by general construction noise at home in the past 10 years, “road maintenance works” (34.3%), “general construction works in construction sites” (33.1%) and “percussive piling in construction sites” (32.7%) were the major types of noise sources causing the annoyance as presented in Figure 3 below.

Figure 3: Annoyance response with respect to different construction activities.

Among different activities in construction sites, road maintenance and repair works (which are believed to have included roadworks associated with public utilities) account for most of the sources that had caused annoyance during the evening and mid-night hours. Although it is understood that various types of mitigation measures (such as better work scheduling, use of purpose-built barriers/enclosures, etc.) would be adopted as fulfilling the CNP conditions for minimizing noise from road maintenance and repair works, it appears that more attention could be paid to reduce the noise at source as the only option by exploring the use of the quietest technologies available. Road maintenance and repairing works are usually required to be carried out at the less busy night hours to avoid causing serious interruption to heavily trafficked roads during daytime. Moreover, road maintenance works may unavoidably have to be carried out on roads in close proximity to residence and be very distinct with lower background noise during unsocial hours. The survey finding also indicates that generally higher proportion of the respondents were highly annoyed by road maintenance works outside the normal day-time hours of 07:00-19:00 as shown in Figure 4 below. It is therefore worth looking into the issue and also devising ways to encourage wider adoption of quieter construction method and equipment for both large scale site formation / foundation works, where intrusively noisy rock excavation often takes place, and small scale routine night-time maintenance activities, where disturbance at sensitive hours looks unavoidable.

Day and time periods which highly annoyed by road maintenance and repair works

14

29

hous of the day

16

16

Saturday

17

17

weekday

45

35

0 5 10 15 20 25 30 35 40 45 5000:00-06:5907:00-11:5912:00-18:5919:00-23:59

% of population

Figure 4: Day and time periods in which respondents were highly annoyed by road maintenance and

repair works.

2596 20% 2596 20% 10% 5% Annoyance of different construction noise Pereussive ing Goneral Ste Actas Road Maintenance Miisgity Anoyed Aaya Demattion “El Sigtty Annoyed Bulng ABA ot Araya ‘ent Kaow Pies

3.3. Domestic Renovation Noise

3.3.1 Hours of Disturbance

Figure 5 below shows that over 50% of the residents had already slept after 23:00 and/or had not yet been awake before 07:00. They therefore warrant more protection against sleep disturbance during this period. This observation supports the current control under the NCO, that between 23:00 and 07:00, no annoyance of any type of neighbourhood noise is to be tolerated. Some 90% of the respondents were asleep around mid-night, compared to 80% found from the 2010 survey [9]. It is also observed that a considerable portion of respondents were still sleeping during the morning hours between 07:00 and 09:00, after when the figures somehow began to flatten. The sleep pattern suggests that it is worthy to provide better protection for the morning hours as some population tends to be still at rest or sleeping during those hours. This may mean better work scheduling for extremely noisy renovation works such as concrete breaking operations would cause less disturbance if they are avoided at morning hours. The survey also explored the time periods in which respondents considered domestic renovation noise or general construction noise having least impact to them or their family. These “least impact” attitudes are shown below in Figure 6.

Sleep periods of respondents

‘Sleep periods of respondents eee ee eee CPELEOECEEERF 58 ed

Figure 5: Time periods in which respondents were usually in sleep

Over 50% of the respondents reported that noise occurring between 09:00 and 18:00 will cause less noise impact to their families, while some 30% of the respondents strongly dislike any noisy works at any time on a Saturday. This is in line with some current house rules set by the property management confining noisy renovation works to the period between 09:00 and 18:00 and disallowing Saturday work for domestic renovations.

Time periods with least noise impact to respondents

Figure 6: Time period during which domestic renovation or general construction noise have least

impact to the family at home. 3.3.2 Responses or Actions Taken When Annoyed

There were several types of responses or actions taken by respondents when annoyed by domestic renovation noise during daytime. “Close the window” (64.3%) and “close the door” (61.6%) were the most common reactions mentioned, followed by “do nothing and tolerate the noise” (30.8%), “leave the premise for a short duration during the works” (15.5%) and “turn on air-conditioner” (12.6%).

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92.0% reported that they had never complained about noise while 6.1% said “sometimes”, 1.5% “a lot of time” and 0.4% “nearly all the time”. When asked about the expected consequences following a complaint, most respondents reported that it could “alleviate the noise” (64.8%), followed by “stop the renovation work / noise immediately” (53.3%) and “change the time of making noise” (35.6%). Only a minor portion expected to “punish the contractor / noise maker / noise source” (5.8%).

Regarding the main party / department to which the complaint had been made, majority of the respondents had made complaints to “management office or property management company” (94.2%). Only a quarter or less had made complaint to “police” (25.3%), “Environmental Protection Department” (22.5%) and “owners' corporations / mutual aid committees or owners committees” (20.4%).

It is quite obvious that noise alleviation by using quieter tools / methods and better scheduling of noisy works are primary targets if people’s aspiration is to be addressed. Means of achieving those goals could be: - promotion / adoption of quieter renovation tools to alleviate noise at source; - confining those noisy operations to small timeslots of the day; and, - advance notification to the neighbourhood on any renovation work so that appropriate actions could be planned ahead.

The property management plays an important role in handling noise from domestic renovation works. Enhancement of Deed of Mutual Covenant (DMC) to empower the formulation and enforcement of house rules on minimizing domestic renovation noise merit further consideration.

Willingness to prolong the renovation period and adopting quiet measures to reduce disturbance to neighbours were also surveyed. 66% of the respondents did not wish to reduce the potential noise disturbances to neighbours by prolonging the renovation period. Likewise, 75% of the respondents did not wish to cover the additional cost from adopting quiet measures. Further community awareness may have to be promoted to enhance mutual sharing of responsibility to minimize domestic renovation noise. 4. CONCLUSIONS

This paper describes the rationale and approach of the study as well as the sampling and questionnaire design. Some of the key study findings were presented, highlighting in particular the prevalence and nature of construction and domestic renovation noise; annoyance and sleeping response of the respondents that would be useful for developing construction noise management strategies in Hong Kong.

It is observed that a higher proportion of the respondents were more annoyed by domestic renovation noise and lodged more complaints than those who were annoyed by general construction works. This might reflect that there is less tolerance towards renovation noise. Among various construction works, “road maintenance works” ranked the top causing annoyance during sensitive hours when people need rest or sleep. Although it is understood that some could be unavoidable due to practical constraints arising from other priorities such as the need to maintain traffic flow on busy roads, it is worthy to promote wider adoption of quieter construction method or equipment to minimize the noise impact.

Besides, noise from domestic renovation was perceived to be the most “highly annoying” source among other environmental noises. Equipment or tools which are operated with a percussive action, such as hand-held breakers, are common sources of noise intrusiveness. The survey findings on people’s living pattern in general suggest that effective house rules say, in terms of time restriction for managing renovation work and using quieter alternative methods / tools could be useful means for reducing the noise impact to the neighbourhood. Further promotion or education efforts would be useful to increase the community’s awareness on the responsibility to reduce renovation noise disturbance. 5. ACKNOWLEDGEMENTS

The authors wish to extend their appreciation to the Environmental Protection Department for their permission to publish this paper. The opinions in this paper are those of the authors and do not necessarily reflect the views or policies of the Government of the Hong Kong Special Administrative Region of the People’s Republic of China. 6. REFERENCES

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