Study Reports

In House Review 2012

ENVIRONMENTAL PROTECTION DEPARTMENT

 
REVIEW STUDIES ON
EXISTING ROADS FOR RETROFITTING WITH NOISE BARRIER
 
1.         BACKGROUND
 
1.1     The Executive Council (ExCo) endorsed at its meeting of 14 November 2000 a policy to address the noise impact of existing roads on residents. Direct engineering measures in the form of barriers or enclosures would be considered where practicable at existing roads generating noise level exceeding 70 dB(A) L10(1 hour) provided that the following guiding principles are complied with:
 
-        the new structures will not obstruct emergency access or fire fighting;
-        they will not undermine road safety or impede pedestrian and vehicular movements;
-        they will not interfere with commercial activities or cause social disruptions; and
-        there will be adequate space and structural capability (applicable to flyovers) for supporting the barrier/enclosure.
 
1.2   Whilst about 30 existing road sections had been preliminarily identified as being technical feasible for retrofitting barriers till 2001, there had been increasing requests from the public, District Council (DC) and Legislative Council (LegCo) members on installing barriers on other existing roads. However, there would be change of circumstances such as increase in traffic flow, change of nature of land uses, redevelopment of residential buildings, etc. that may affect the technical feasibility of road section for retrofitting barrier.  The government had conducted review studies as necessary following the guiding principles to identify any further road sections for implementing engineering solutions.
 
1.3    The review studies included a total of 50 road sections as shown Appendix 1.
 
1.4    The extent of each road section studied is shown in the site plans in Appendix 2.
 
2.         REVIEW METHODOLOGY
 
2.1       The objective of the review studies was to identify which road sections would not be non-starters for retrofitting barriers based on the information to be collected within the scope of this preliminary study.
 
2.2       The scope of the review studies included:
 
-           conducting appraisal against the guiding principles based on the latest available information and relevant guidelines issued by the concerned departments;
 
-           conducting preliminary noise appraisal on the concerned road sections and the nearby existing roads to identify the effectiveness of the barriers;
 
-           checking the planning history of the noise sensitive receivers (NSRs) to identify any noise mitigation measures adopted during the development stage of the NSRs;
 
-           estimating the construction and other relevant cost figures and time required; and
 
-           preparing unmitigated scenario and two mitigated scenarios for comparison.
 
2.3       The review study has been conducted based on a desk-top review of the relevant Outline Zoning Plans (OZPs) and 1:1000 scale survey maps produced by Lands Department (Survey and Mapping Office) as well as the Traffic Aids Records provided by the Transport Department (TD). These OZPs and survey maps provided information such as road alignment, footpath, cycle track, building location and type, land-use, etc. Other traffic-related features such as traffic signs, pedestrian crossing facilities, bus lanes, etc. were identified based on the Traffic Aids Records. Site visits were conducted to verify existing situation and identify if there were any recently constructed elements.
2.4       In addition to the four Guiding Principles listed in the above Section 1.1, the acoustical effectiveness of noise mitigation measures has also been taken into account in the review studies.
 
Guiding Principle 1 (GP1) – Space Availability
2.5       This Guiding Principle is the fundamental requirement for retrofitting barriers on existing road sections. Structural space must be available for constructing the foundation in addition to accommodating the barriers themselves. For retrofitting barriers on at-grade roads, a minimum space of 1m is required for foundation and column even if short pilings are used for the foundation. Figure 1 illustrates the process of the space availability considerations.
2.6       A minimum horizontal clearance of 1m should be provided between kerb of carriageway and panels/columns of barriers on the footways, verge or central reserve as referenced to Transport Planning and Design Manual (TPDM) Volume 2 issued by Transport Department.   In case that any street furniture such as untensioned corrugated beam barrier is proposed between the carriageway and the barriers, additional space availability concern should be considered.
2.7       In association with the minimum space for the foundation and horizontal clearance as mentioned in Sections 2.5 and 2.6, respectively, a minimum space of 2m from the road kerb is needed. In case that any street furniture such as untensioned corrugated beam barrier is proposed between the carriageway and the barriers, additional space availability concern should be considered. Besides, adequate additional roadside space should be reserved for the provision of traffic signs and associated facilities as necessary.
2.8       It is necessary to avoid obstruction to pedestrian flow according to the requirement of TPDM. After erection of the barriers, space of 1.6m (2.0m after revision of the TPDM) to 4.5m should be maintained for unobstructed pedestrian passage.
2.9       For the general requirement of a vertical barrier on spread footing, the minimum space requirement is 3.5m. For locations that involve flyovers, where pile is not feasible for the foundation of barrier, an independent structure for barriers is required instead. A construction space of more than 3.5m for the foundation may be required. The structural design of strengthening the existing flyover will need to be considered in detailed design stage.
 
Guiding Principle 2 (GP2) – Fire Fighting and Emergency Vehicular Access (EVA)
2.10    Fire safety in a building is determined by a number of factors, one of which is the means of access enabling fire-fighting personnel to rescue and fight fire. This Guiding Principle aims to maintain access for fire-fighting personnel. Therefore, barriers should not be provided at the EVA points. Also, it is essential that affected major building facades for fire safety and rescue purpose should be within the reach of the fire engines. In general, EVA with a minimum width of 6m should be provided adjacent to affected facades. The obstructed distance between the fire engine and the major building facade for fire safety and rescue purpose should be less than 10 m. Furthermore, for flyover situations, Fire Services Department (FSD) requires that a 4.5m horizontal clearance between the outer edge of the flyover structure and the adjacent building facade be maintained. Figure 2 illustrates the process of emergency access considerations.
2.11    The erection of a noise barrier at any central reserve should also take into account of the provision of emergency crossings at the respective road sections.
 
Guiding Principle 3 (GP3) – Road Safety, Pedestrian and Vehicle Movements
2.12    This Guiding Principle aims to ensure that the new structures will not undermine road safety or impede pedestrian and vehicular movements. The noise barrier should not be erected at locations where they may pose any hazard to road safety or reduce the degree of road safety. This is particularly essential for barriers close to an existing intersection as it could affect the visibility of both pedestrian and drivers. Also, provision of a barrier along a bend in the road may obstruct the sight line for stopping safely. The logic is that the principle of “Seeing and be seen” must not be violated.  The sight distance should not be less than the desirable minimum as stipulated in TPDM. Figure 3 illustrates the process of road safety considerations.
2.13    It is necessary to avoid having the noise barrier cause an obstruction to pedestrian flow. According to the TPDM, space ranging from 2m to 4.5m should be maintained for pedestrian passage in urban situations depending on pedestrian volume.
 
Guiding Principle 4 (GP4) – Socio-economic Concern
2.14 This Guiding Principle aims to ensure that the location of new structures for noise barriers will not interfere with street-level commercial activities including all shops, restaurants, cinemas, etc.
2.15 Apart from commercial activities, the new structure for noise barriers could not disrupt any social activities, e.g. pedestrian crossing, landscape appreciation and recreational place accessFigure 4 illustrates the process of socio-economic considerations.
2.16 Such commercial activities were observed and recorded during site visits of the concerned road sections. This information has been considered in locating potential noise barrier on the existing roads.
 
3.     FINDINGS OF THE REVIEW STUDIES
 
3.1     Appendix 1 is a summary of the findings.
 
3.2     Out of the 50 road sections, the review studies found 3 road sections were not generating excessive traffic noise (i.e. traffic noise levels not exceeding 70 dB(A) L10(1 hour)).
 
3.3     Out of the other 47 road sections, the review studies found retrofitting noise barriers on 18 sections would be technically infeasible on the whole sections. In other words, retrofitting noise barriers found technically not infeasible on at least part(s) of each of the 29 road sections left.
 
4.         RECOMMENDATION
 
4.1     The noise barriers found technically not infeasible on each of the 29 road sections are shown in Appendix 3.
 
4.2     Each identified mitigation option should be further subjected to detail study during engineering design stage to develop the most optimum option for implementation. The detail study includes the following:
Engineering Consideration
Buildability
Safety
Trafic Management during Construction
Detailed Cost Evaluation
 
Environmental Considerations
Noise Impact
Air Quality Impact
Landscape Impact
Visual Impact
 
4.3     Out of the 29 road sections, further study for confirming the technical feasibility of retrofitting noise barriers or enclosures on 14 sections were recommended and have been/would be completed by HyD as shown in Appendix 1.
 
4.4     For the remaining 15 sections where retrofitting noise barriers were found technically not infeasible, the recommendations are as follows:
 
Ap Lei Chau Bridge Road
 
1 barrier of 60m long near Shan Ming Street was identified as "not technically infeasible". Leisure and Culture Services Department (LCSD) had objection to the barrier scheme in view of adverse impacts on a large number of existing trees. Therefore, further study of the technical feasibility is not recommended.
 
Ching Hong Road
 
2 barriers, one of which was shorter than 100m, near Tsing Shing Court were identified “not technically infeasible”. The acoustical performance of the identified barriers would be low (less than 10% of the dwellings at Tsing Shing Court and Cheung Hong Estate would be benefited). Moreover, erection of barriers in front of Tsing Shing Court only may not be well accepted by the residents of Cheung Hong Estate, further study of the technical feasibility is not recommended.
 
Chiu Shun Road
 
The road section between Po Ning Road and Ngan O Road had been paved with Low Noise Road Surfacing (LNRS) material under the LNRS Trial Programme in 2006, the traffic noise levels at the concerned noise sensitive receivers along Chiu Shun Road were reduced to within the 70dB(A) standard.  Retrofitting of noise barrier is therefore no longer justified.
 
Fanling Highway (between San Tin Interchange and Ho Sheung Heung Road Interchange)
 
Widening of Fanling Highway (between San Tin Interchange and Ho Sheung Heung Road Interchange) is being proposed under the "NENT New Development Areas" project, more comprehensive noise mitigation measures will be incorporated into the proposed road widening works. Retrofitting of noise barrier at this road section is therefore not recommended at the current stage.
 
Fanling Highway (between Ho Sheung Heung Road and Yin Kong Tsuen)
 
Widening of Fanling Highway (between Ho Sheung Heung Road and Yin Kong Tsuen) is being proposed under the "NENT New Development Areas" project, more comprehensive noise mitigation measures will be incorporated into the proposed road widening works. Retrofitting of noise barrier at this road section is therefore not recommended at the current stage.
 
Fung Shue Wo Road
 
1 barrier near Yee Kui House, Tsing Yi Estate, and 1 barrier near Tsing Fai San Tsuen were identified to be “not technically infeasible”.  In 2012, the noise situation was reviewed. The noise measurement results revealed that the road traffic noise at Yee Kui House (the worstly affected NSR) was below the 70dB(A) criterion. Thus, the noise barrier is no longer justified. At Tsing Fai San Tsuen, the measured road traffic noise level still exceeded 70dB(A). Erection of the identified barrier near Tsing Fai San Tsuen would require felling or transplanting of the mature trees along the road section. Moreover, the acoustical performance of the identified barrier near Tsing Fai San Tsuen would be low (no more than 10% of the dwellings along the road would be benefited),. Therefore, further study of the technical feasibility is not recommended.
 
Hoi Wing Road
 
3 barriers, 2 of which were less than 100m, were identified to be “not technically infeasible”.  In 2012, the noise situation was reviewed. The noise measurement results revealed that the traffic noise levels were below the 70dB(A) criterion. Thus, the retrofitting noise barriers are not longer justified.
 
Island Eastern Corridor
 
1 barrier near Lei King Wan was identified “not technically infeasible”. There is a large buffer distance between the IEC and the affected building blocks at Lei King Wan. The noise barrier largely falls in front of the existing Caritas Lok Yi School and the Sai Wan Ho Playground. The acoustical performance of the identified barrier would be low (no more than 11% of the dwellings in the study would be benefited) due to noise screening effect already provided by the existing school. Therefore, further study of the technical feasibility is not recommended.
 
Lion Rock Tunnel/Sha Tin Road
 
The proposed alignment of Trunk Road T4 in Sha Tin covered the concerned road section, more comprehensive noise mitigation measures have been proposed to be incorporated into the development of Trunk Road T4. Also, the existing 185m long x 4m high vertical barriers outside Pok Tat House of Pok Hong Estate have already provided some noise screening to the affected noise sensitive receivers, retrofitting of noise barrier at this road section is therefore not recommended at the current stage.
 
Lung Cheung Road (BeaconHeights Section)
 
1 barrier near Dynasty Villa was identified “not technically infeasible”. The acoustical performance of the identified barrier would be low (less than 9% of the dwellings at DynastyVilla & BeaconHeights would be benefited). Thus further study of the technical feasibility is not recommended.
 
Lung Cheung Road (Wong Tai Sin Section)
 
1 barrier near Ka Keung Court, and 1 barrier near Wong Tai Sin Police Quarters (now known as "Lions Rise") were initially identified "not technically infeasible". Subsequent detail study indicated that there is insufficient space to erect effective barriers in order to maintain adequate footpath width. There would also be serious traffic impact to Lung Cheung Road during construction of the barriers. Thus, further study of the technical feasibility is not recommended.
 
Princess Margaret Road
 
1 barrier near Wing On Court and Greenfield Terrace was identified “not technically infeasible”. The acoustical performance of the identified barrier would be low due to existence of building podium and carpark. As the erection of barrier is not effective, no residential unit could be protected from traffic noise impact. Thus, further study of the technical feasibility is not recommended.
 
Sha Tau Kok Road (Lung Yeuk Tau Section)
 
The traffic flow at the concerned road section will be increased significantly due to the development of the “NENT New Development Areas” (NENT NDA). Noise mitigation measures for the concerned road section will be considered in the NENT NDA study, retrofitting of noise barrier at this road section is therefore not recommended at the current stage.
 
Tsing Tin Road
 
6barriers were identified to be “not technically infeasible” with 5 of them less than 100m in length. As Tsing Tin Road is within the study area of Highways Department’s Tuen Mun Western Bypass Project (TMWB), the interfacing issues with TMWB and the exact extent of barriers would be reviewed later when more information is available from TMWB Project.
 
 Wai Yip Street
 
1 barrier near LagunaCity was identified to be “not technically infeasible”. In 2012, the noise situation was reviewed. The noise measurement results revealed that the road traffic noise level was below the 70dB(A) criterion. Therefore, the retrofitting noise barrier is no longer justified.
 
5.         CONCLUSION
 
5.1    50 road sections were reviewed in the studies. It was found that 3 road sections were not generating excessive traffic noise. Out of the remaining 47 road sections, retrofitting noise barrier on the whole sections would be technically infeasible.
 
5.2    The review studies identified 29 road sections that are technically not infeasible to provide mitigation measures in the form of noise barriers. Nonetheless, further study of the feasibility of retrofitting noise barriers on 15 road sections out of the 29 are not recommended due to various considerations such as updated noise environment and acoustical effectiveness.
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