Measures
to Address Noise Impact of Existing Roads
(ACE
Paper 39/2000)
For discussion
PURPOSE
This paper briefs Members on the new policy to address
noise impact of existing roads on residents in the neighbourhood.
INTRODUCTION
- The Executive
Council has approved the Government's proposal of introducing
a new policy to address the noise impact of existing roads on
residents. Under the new policy, -
- engineering
solutions, by way of retrofitting of barriers and enclosures,
and resurfacing with low noise material, should be implemented
where practicable at existing excessively noisy roads in accordance
with the guidelines set out in paragraphs 8 and 14 below;
and
- non engineering
solutions, such as traffic management measures, should be
explored on a case-by-case basis and implemented where practicable
at roads where engineering solutions are impracticable or
where engineering solutions alone are inadequate in reducing
the noise to an acceptable level.
BACKGROUND
Noise
Limit
- We have adopted
the existing noise limit of 70dB(A) L(10) (1 hour)1
("the noise limit") in the Planning Standards and Guidelines since
mid-1980's for the planning of new roads. As Annex
A shows, this limit is the same as in the UK and USA,
and less stringent when compared with Australia and the Netherlands.
Existing
policy for mitigating traffic noise
- Under existing
policy, when planning new roads, the relevant department or developer
must ensure that traffic noise will stay below the noise limit.
If it is envisaged that traffic noise generated will exceed the
noise limit, they must adopt all practicable direct measures such
as adjusting the alignment and erecting barriers or enclosures
to reduce the impact on residents in the neighbourhood. Where
direct measures are inadequate, they have to provide affected
residents with indirect technical remedies in the form of good
quality window and air-conditioning. The current policy applies
to new roads only.
- To ensure
that individual vehicles do not produce excessive noise, we introduced
legislation in 1995 requiring all newly registered vehicles to
comply with stringent noise standards. We will continue to move
in step with the European Union on this front. In addition, we
have resurfaced all high-speed (70km/hr or above) roads with low
noise material except those with steep gradient or sharp bends
where the use of such material is unsuitable. The material has
reduced noise by about 4 dB(A). However, the effect of the resurfacing
programme in reducing noise is limited: it covers only 11 km of
all roads.
The
problem with existing roads
- According
to Environmental Protection Department's assessment, 655 out of
the 3,000 existing roads in Hong Kong are currently generating
noise in excess of the noise limit. The majority of these roads
were planned and constructed before the existing policy for new
roads took effect. The increase in traffic has exposed more families
to high levels of traffic noise above 70dB(A). This does not mean,
however, all flats near these 655 roads are exposed to high noise
levels. This is because the degree of noise impact would depend
on factors including height and location of the flats and any
structure that screens the line-of-sight to the road. For example,
flats screened by podium, building structure or are facing away
from the road would be less affected by traffic noise.
THE
NEW POLICY
Retrofitting
of barriers/enclosures
- With the
erection of barriers or enclosures, neighbouring residents would
experience noise reduction from 1 to 19 dB depending on the height
and location of their units relative to the barriers/enclosures.
Environmental Protection Department has studied the feasibility
of retrofitting barriers/enclosures on existing roads that are
generating noise in excess of the noise limit and concluded that
it would be technically feasible to retrofit such structures on
a limited number of roads.
Guiding
Principles
- Based on
Environmental Protection Department's studies, barriers/enclosures
will be retrofitted on roads -
- where
they are generating noise in excess of the noise limit for
residential premises along their alignment; and
- where
the retrofitting of such structures is technically feasible,
that is -
- 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 for the retrofitting.
Need
for aesthetic design
- In pursuing
the retrofitting programme, it is important that we pay due attention
to the design of the barriers or enclosures. Otherwise, we will
be resolving one problem and creating eyesores on the landscape.
To prevent the barriers/enclosures from being unduly obtrusive,
the landscape and visual impacts would be included in the environmental
impact assessment process of the retrofitting programme. Possible
design that would enhance the landscape and visual quality or
make the project visually compatible with the vicinity would be
fully explored. Some examples of such designs are at Annex
B
.
In addition, the environmental impact assessment would include
air quality impact and disturbance of existing vegetation to ensure
that such environmental considerations are not unduly compromised.
Phasing
the retrofitting works
- Based on
the guiding principles in paragraph 8 above, we have currently
identified 29 existing road sections (including 6 flyovers) for
retrofitting. We estimate that 24,000 residential units will benefit
from the programme. For the majority of the beneficiaries (70%),
the programme will reduce the noise to which they are exposed
to a level below the noise limit.
- The retrofitting
programme is massive. Subject to availability of funds, we intend
to implement it in stages with priority given to roads with the
highest noise exposure and number of affected residents. A preliminary
implementation timetable has been drawn up at Annex
C. We will consider refining it to also synchronise the timing
for retrofitting certain roads with that of new roads that have
already been planned to adjoin them. This will minimize disturbance
to residents and road users arising from the different works projects
and where possible achieve some savings in the project costs.
- It should
be noted that the proposed retrofitting programme covers only
4% of the 655 excessively noisy roads currently identified. There
are still over 600 excessively noisy roads that we need to deal
with.
Resurfacing
with low noise material
- As mentioned
in paragraph 5 above, the low noise resurfacing programme has
been restricted to existing high-speed roads. The material is
considered less suitable for local roads where frequent stop and
start due to traffic lights, loading and unloading activities
and parking would shorten its life considerably. It is estimated
that while a local road with normal asphalt surface needs resurfacing
once every six years, one with this type of low noise surfacing
needs to be resurfaced at least once every three years. This would
mean higher maintenance costs, more traffic disruption and inconvenience
to drivers, pedestrians and shop operators. Consequently, under
existing policy, low noise surfacing materials are used on new
local roads under exceptional circumstances where noise reduction
is an absolute necessity but cannot be achieved by any other means.
- We will extend
the above policy for new local roads to existing local roads.
Environmental Protection Department has currently identified 72
roads as candidates for feasibility study. The preliminary assessment
is that 36 of these roads will meet the site geometry and traffic
volume for the low noise surfacing materials to be effectively
applied while the remaining 36 will exceed the desired traffic
volume control by up to 20%. This will mean that if low noise
surfacing is applied to these 72 road sections, half of them may
need to be resurfaced once every two years instead of three years.
The feasibility of resurfacing these 72 road sections will be
studied by Environmental Protection Department and Highways Department
in details taking into account other engineering considerations.
Subject to satisfactory results of the study, a resurfacing programme
will be implemented.
- We estimate
that the resurfacing of the 72 road sections will benefit 40,000
residential units. About 11% of them will experience a reduction
in noise to a level below the noise limit after the resurfacing.
Non-engineering
measures
- For the existing
excessively noisy roads where engineering solutions are impracticable,
and for roads where engineering solutions would not be adequate
in reducing the noise level to below the noise limit, we will
explore on a selective basis and implement non-engineering options
such as traffic management measures where practicable case-by-case.
- However,
any control measures would benefit some and inconvenience others.
Considerable operational and enforcement problems are involved.
We need to examine the feasibility of introducing such solutions
most carefully and will consult the relevant District Councils
and the transport trade in considering such proposals. In the
longer term, the noise impact of the existing roads should be
addressed in a comprehensive manner through urban renewal and
better town planning efforts.
WAY
FORWARD
- There is
no ideal solution to address the noise impact of existing roads
on residents, which has existed for many years. But the Administration
is doing all it can within the current constraints. Although we
expect that the exposure of some residents to excessive traffic
noise after implementation of the above proposals would still
be unavoidable, the proposed measures would have an appreciable
mitigating effect and bring overall improvement to the living
environment of those being affected by excessive traffic noise
generated from existing roads.
- We will brief
the relevant District Councils (DCs) on the new policy and the
proposed implementation programme. We will seek funding for the
retrofitting and road resurfacing works for the roads currently
identified, and for any additional roads covered by the new policy.
Environment
and Food Bureau
December 2000
1 L10(1 hour) is the noise level exceeded for 10% of an
one-hour period, generally used for road noise at peak traffic flow.
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