For discussionon
10 June 1999

LegCo Panel on Planning, Lands and Works
Policy on mitigation of traffic noise from roads


Arising from the discussion of the project on West Rail (phase 1) - essential public infrastructure works for Sham Shui Po section at the Public Works Subcommittee (PWSC) meetings on 28 April and 12 May 1999, this paper sets out the existing policy on mitigation of traffic noise impacts from roads.

Planning of new roads

2. Proponents of new roads, major extensions or improvements to existing roads are required to go through the environmental impact assessment (EIA) process to assess and evaluate the impact of the proposed projects on both the existing and planned sensitive uses, and to propose and implement practicable mitigation measures to be applied on roads to abate the traffic noise impacts.

3. Planned sensitive uses include planned residential developments and schools proposed in any draft or approved Outline Zoning Plans or any other land use plans published by the government at the time of the EIA for a new road.

4. All practicable direct technical measures on the new roads or major extensions are required to be implemented before any measures on sensitive receivers are to be considered.

5. After the adoption of all practicable measures at source, if the residual noise impacts are envisaged to exceed the established criteria, the proponent of the new road should need to examine the potential environmental constraints and mitigation measures at planned sensitive receivers. These measures include setback, building disposition and podium structure. The practicality and feasibility of these mitigation measures will need to be evaluated and confirmed during the EIA process. During the EIA process, the road proponents would need to ensure, to their best endeavour, that the development potential of a site would not be affected. Any agreed feasible measures on sensitive receivers would need to be made known to the implementation agents of the sites.

6. Any new sensitive uses proposed after the EIA of a road project has been completed will be dealt with through the planning process, having regard to the development constraints imposed by the roads.

Measures on roads

7. Under the established practice, the boundary of noise assessment for roads is 300 metre from either side and along the full stretch of a proposed road. The cumulative traffic noise impact from both the existing and proposed roads on noise sensitive receivers in the study area would be assessed against the noise limits under the relevant Technical Memorandum issued under the EIA Ordinance. If the noise impacts exceed the limits, direct noise mitigation measures such as noise barriers, enclosures and low noise surfacing are to be considered for implementation on the new roads where practicable.

Effect of noise mitigation measures

8. Doubling the distance separation between a road and sensitive development means a 3dB(A) traffic noise reduction. However, because of the shortage of space, there is a limit in the use of buffer distance to fully address the noise impact. The effect of barriers on road (or non-noise sensitive building blocks at roadside) would depend on their height and relative location of the sensitive receivers. Barriers may typically reduce traffic noise impact by a few dB(A) to 15dB(A). Higher noise reduction may be achieved if the barrier or enclosure could completely shield sensitive use from the road. On the other hand, the effect of low noise surfacing would reduce traffic noise by about 4 dB(A) from high-speed roads and 3 dB(A) from low-speed local roads.

9. Setbacks supplemented with other building layout designs such as podium structure would help to reduce traffic noise impact. However, the setback on podium arrangement could usually protect the lower floors of high rise developments only. Orientating building windows instead of overlooking whole stretch of the road to overlooking only half of it, would mean a 3 dB(A) noise reduction.

Policy to retrofit barriers to redress noise impacts from existing roads

10. At present, there is no government policy requiring the retrofitting of direct mitigation measures such as roadside barriers or enclosures to redress traffic noise impacts from existing roads.

11. The government is now reviewing the findings of a territory-wide study commissioned by the Environmental Protection Department on the technically feasibility of retrofitting noise barriers and enclosures on existing roads. We aim to formulate a programme on retrofitting traffic noise mitigation measures to suitable existing roads within this year and to consult the public on the proposed programme by early next year.

Planning, Environment and Lands Bureau
June 1999