Costs and effects of traffic noise abatement measures: Basis for a national programme

Applied Acoustics 25 (1988) 149-168

Costs and Effects of Traffic Noise Abatement Measures: Basis for a National Programme G. Nielsen Institute of Transport Economics, PO Box 6110 Etterstad, N-Q602 Oslo 6, Norway

& s. Solberg KILDE, PO Box 229, N-5701 Voss, Norway (Received 29 May 1987; accepted 24 March 1988) ABSTRACT The paper reports on a Norwegian study of the estimated costs and effects of different traffic noise abatement measures. The study describes the extent of road traffic noise problems and possible countermeasures in seven districts in the Norwegian towns of Oslo, Kristiansand and Harstad. The effects and costs of different abatement measures in the period 1986-2000 are calculated in order to suggest the most cost-effective policies. A simple extension of the results to the whole country forms a major basis for a new national traffic noise abatement programme. Without new abatement measures the present noise situation in the study areas will improve by the year 2000, but the traffic noise problems will by no means be solved. New action is needed, and according to this study, the most cost-effective abatement measures are stricter noise regulations for motor vehicles, area traffic management, lownoise road surfaces and insulation of the most exposed dwellings. Priority should be given to actions in densely populated, central urban areas.

1 THE PURPOSE OF THE STUDY In this paper we summarize and discuss the m e t h o d and results o f a Norwegian study o f costs and effects o f different traffic noise abatement 149 Applied Acoustics 0003-682X/88/$03.50 © 1988 Elsevier Science Publishers Ltd, England. Printed in Great Britain

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G. Nielsen, S. Solberg

measures. ~ The purpose of the study was to give the Norwegian Pollution Control Authority (NPCA) advice on the most cost-effective policies in a national programme for the abatement of road traffic noise towards the year 2000. The study was an input to a national programme with a long time perspective, and the level of detail had to be limited. Only broad policy conclusions were aimed at. Information available about the present traffic noise situation in different parts of Norway also restricted the accuracy of the national estimates made in the study. Even the data on costs of noise abatement measures are somewhat uncertain. However, this study is the first Norwegian. attempt to analyse a national traffic noise abatement programme in terms of cost-effectiveness of different measures. It represents the first stage in the development of practical working methods--including computer programmes--which are necessary for a national programme.

2 METHOD 2.1 Study areas and future situations

By combining existing data from various surveys we were able to provide a broad, quantitative description of the present traffic noise situation and trends in the number of traffic noise exposed dwellings in Norway. 3'15 However, a more comprehensive and varied description of the effects and costs of different abatement measures in the shifting circumstances of Norwegian communities was needed. Therefore, detailed model studies were made in seven built-up districts in the towns of Oslo, Kristiansand and Harstad. The initial methodology in the model studies was adopted from an exploratory study by the Nordic Joint Group on Noise Abatement, NBG. 2 The study areas were chosen so as to give a varied selection of different types ofdevelopment in Norway, i.e. from a dense urban area in central Oslo (urban region with 850 000 inhabitants) to the ribbon development of the small town of Harstad (20 000 inhabitants). Together, the areas have 14 000 dwellings. Of these, some 10 500 (75%) are exposed to outdoor traffic noise of more than 55 dB(A). This 24-hour equivalent noise level is the limit recommended by the Ministry of the Environment for the planning of new development. The noise situation was described for 1984, and for the T R E N D situations in 1990 and 2000. For the study area in Oslo, we also calculated the noise

Tragic noise abatement measures

151

condition in 1974 in order to estimate the effects of environmental improvement measures during the past decade. For 1990 and 2000 A L T E R N A T I V E situations were also studied, including the effects of different, possible noise abatement measures. 2.2 Modelling the areas and their acoustical conditions The areas under study were described in a road link and a building register. The road link register contains initial information on traffic and topography, and calculated descriptors of noise emission. The building register contains information on house type, orientation, outdoor propagation parameters, sound insulation and number of inhabitants. The basic computations of noise levels were based on the Nordic joint model for road traffic noise calculation. 4 2.3 Comprehensive noise and nuisance description The nuisance from road traffic noise is complex, and several aspects were considered. In this study indoor situations and urban driving conditions were emphasized. The indoor situation was considered to be the most important for everyday life, and building insulation could then simply be included in the measures. Most road traffic noise problems in Norway are covered by urban driving conditions since the country has few high-speed roads in builtup areas. From the literature s- a and from the results of three field surveys in the city of O s l o , 9 - 11 three descriptions of noise nuisance relevant and practical for the study were synthesized: 12 (1) Annoyance, calculated as a function of indoor, 24-hour equivalent noise level and the percentage of heavy vehicles (gross weight above 3.5 tons) in the traffic (Fig. 1). (2) Sleep disturbance, calculated as a function of the number of noise incidents above 50 dB(A) inside the sleeping room during the night (22.00-06.00 hours) (Fig. 2). (3) Communication disturbance, calculated as a function of indoor, 24hour equivalent noise level (Fig. 3). All indoor noise levels and nuisance descriptions are based on closed windows, which for the average Oslo dwelling gives an outdoor-indoor level difference of 30 dB(A) (outdoor level, 2 m in front of facade, includes 3 dB(A) from reflections). In addition to the indoor situation, outdoor noise levels (in sidewalks and gardens, and outside windows) were also considered. The situations on the

G. Nielsen, S.

152

Solberg

1001 5%

80.

i, 5%

20

~ 2o

10

o

0 Equivahmt indooc noim level, L i, eqv, d B A

. 40, Number of ~

80

120

situationsabove 50 d B A

Fig. 2. Model for the estimation of sleep disturbance, as a function o f the number of traffic noise incidents above 50 dB{A) inside the sleeping room during the night (22.00-06.00 hours).

Fig. 1. Model for the estimation of annoyance from urban road traffic noise, as a function of indoor, 24-hour equivalent noise level and the percentage of heavy vehicles.

noisy sides of the dwellings or premises were described. For dwellings having a 'quiet' side, these noise levels were also calculated. 2.4 Noise abatement measures In principle, all known traffic noise abatement measures were considered: insulation o f buildings; noise screening; stricter emission limits on vehicles; traffic management; low-noise road surfaces; bypasses; changes in building use and traffic reduction. The measures were described with their acoustical effects, costs and some other important consequences, as far as they are known today. Choices of different measures and their extent were made in close contact with the local

:I.° Rot '~40 t 20 O.0

J ~ .~/./..t f/" 30~*~/"

40

•

./'/'/" 50

55

Equivalent indoor noiu level, Li, eqv, dBA Fig. 3.

Model for the estimation o f communication disturbance, as a function of indoor, 24hour equivalent noise level.

Traffic noise abatement measures

153

TABLE 1 Overview of Assumed Noise Reductions of Different Abatement Measures Measure

Examples of expected indoor noise reduction,

Remarks

L~ (d~.4)) Stricter noise regulations for vehicles

3.8

Year 2000, 10% heavy vehicles

Local bus requirements

3"1

Year 1990, 10% buses, 90% light vehicles

Noise barrier

8

Ground floor, 25 m from road, 2 m high barrier

3 7-19

Heavy wall (concrete, masonry etc.) and doubleglazed windows

11

Example in Oslo, effect completely dependent on the local situation

Noise insulation: Window sealing New sound-attenuating windows. (three classes) By-pass tunnel for main urban roads Low-noise road surface

Area traffic management: Main through roads Local roads

Main road with speed limit 60-70km/h or more, 10% heavy vehicles - 1 6

Examples from inner-city schemes in Oslo

planning authorities. In m a n y cases they were based on existing plans or proposals. Thus, the potentials of different abatement measures were realistically assessed in all study areas. The potential use of barriers along roads or near the receiver was restricted to places where little aesthetic or practical disadvantage would occur. The building insulation included f o u r grades o f windows, improvement o f lightweight walls, mechanical ventilation and sun screening. The assumed noise effects o f the different measures are indicated in Table 1.

2.5 Assumptions about future vehicle noise emission Vehicle noise limits The vehicle noise emission limits in N o r w a y have generally become stricter since 1972. Existing regulations imply that N o r w a y adopts the policies o f the

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EEC. For the future, two different developments were considered to be realistic, and thus formed the basis for two policy alternatives: (1) T R E N D follows the accepted strictening for the EEC countries, to 77dB(A) for 1990-91 for light vehicles and to 84dB(A) for heavy vehicles. This assumes a second-gear test for the ISO 362 method. (2) A L T E R N A T I V E is a more restrictive national policy, implying noise limits from 1990 of 75 dB(A) and 80 dB(A) for light and heavy vehicles, respectively.

Noise emission in urban traffic The ISO 362 test is not very good at describing the noise emission for light vehicles under urban driving conditions. In addition, some technical modifications on the new vehicles (gear ratios, etc.) are more attempts to adapt to the test method than noise reducing measures. The noise reduction in urban traffic is estimated for five different vehicle generations in Table 2. For the T R E N D development, the noise reduction under urban driving conditions is assumed to be only half of the dB(A) reduction shown by the ISO 362 test. The A L T E R N A T I V E development is assumed to require more effective measures (encapsulation, new engine design), giving larger relative benefit to urban driving conditions. Tyre/road noise may dominate over noise from other vehicle sources when assessed outdoor for traffic at higher speeds. However, in our indoor/urban model, we assumed that tyre/road noise will not influence the total emission from the tabulated vehicle generations.

Contribution from several generations of vehicles In Norway, new cars are driven longer annual distances than older ones 13 (Fig. 4). Our model assumes a life-time of 12 and 10 years for light and heavy

TABLE 2 Reduced Noise Emission from Different Generations of Light Vehicles

Vehicle generation (first year with stricter limit)

1979 1982 1990 TREND 1990ALTERNATIVE

Noise reduction re 1972 ISO 362 second gear (dB(A)) 2 3 4 8

Urban driving, indoor Leq (dB(A)) 1 1'5 2 6

155

Traffic noise abatement measures

10 °

it

l-1_ L

J l

C'. . . . . . . . . . 1 2

3

, , , , , 8

.Agegroup of th.e ca..-',,y ' ~

13 14 15 +

Fig. 4. Total mileage made by each age group of cars in Norway 1980.13

vehicles respectively, and a linear decrease in mileage over the life-time. Thus we may have up to three generations of vehicles in the traffic at a given time. The reduction in noise emission over time from a given traffic flow is shown in Fig. 5. The A L T E R N A T I V E development gives some 4 dB(A) extra noise reduction in the year 2000 compared to the T R E N D . At conditions other than indoor/urban, the obtainable noise reduction will be smaller. The limitations given by other conditions are indicated in the figure. zx L ~ i , dBdL

-2

- 2.4-- O,H

'-441--

~H

i -4' .~ -6-

- - 6 - t - ~ O,U

~- 8 . . - -

I,U

Fig. 5. Estimated reduction in noise emission, Leq, from a given traffic volume in Norway, 1978-2000. The traffic contains 10% heavy vehicles. Time of introduction for new type approval limits are indicated. T R E N D implies introduction of accepted EEC limits. ALTERNATIVE assumes introduction of stricter national limits in 1990-91. Different conditions of assessment give different limitations in obtainable noise reduction: O = outdoor; I = indoor; H = highway traffic; U = urban traffic.

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G. Nielsen, S. Solberg

Costs of ALTERNATIVE development The T R E N D development is supposed to imply no particular costs relevant to a new noise abatement programme. The A L T E R N A T I V E is assumed to give light vehicles with 4% higher cif-price, 90 N O K per year (100 N O K = approx. 13-5 US $) higher costs for maintenance, 340 N O K extra costs for replacement of exhaust system and 4% fuel savings. The savings are due to assumptions of more economic slow-running engines, or encapsulated engines with a higher and more economical temperature under urban driving conditions. This gives a discounted cost (real social cost) of 1230 N O K per light vehicle. Heavy vehicles are assumed to be subject to a similar rise in cif-price, a 1.5% increase in maintenance costs, 650 N O K extra costs for the replacement of exhaust systems (two replacements) and a minor reduction in payload. This gives a discounted cost of 4750 N O K per heavy vehicle.

2.6 Analysis of cost-effectiveness

Describing the effects The effects of the noise abatement measures in each study area were described by the differences in the noise situation in 1990 or 2000 between the T R E N D situation (no new measures) and the situations with the A L T E R N A T I V E measures in operation. The following five indicators were calculated as the percent change in relation to the T R E N D situation: (1) The percentage of pavement length with an equivalent outdoor noise level of 60 dB(A) or more (E 0. (2) The percentage of dwellings with an equivalent outdoor noise level of 65 dB(A) or more (E2). (3) The percentage of dwellings with an equivalent indoor noise level of 35 dB(A) or m o r e (E3). (4) The percentage of persons (inhabitants) very annoyed by road traffic noise, according to the model in Fig. 1 (E4). (5) The percentage of persons (inhabitants) with sleep disturbance due to road traffic noise, according to the model in Fig. 2 (E5). Other indicators could have been used, but these were considered to give a fairly broad basis for the comparison of different measures. Among these indicators, the second last (annoyance, E4) was used as the basic one for the national estimates. This was considered the best single, general indicator, but we will later in the paper discuss the relevance of other criteria for the formulation of a noise abatement policy.

Costs The costs of the measures under study were estimated on the basis of existing

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157

evidence and 'informed guesswork'. Only additional costs (on a real social economic basis) to the T R E N D situation were taken into account, both investments and operating costs. The economic benefits of energy savings were included. All costs were discounted to 1984, and are in 1984 prices. A real interest rate of 7% was used, as recommended by the Department of Finance. To facilitate the comparison between different study areas and the extension of results to a national level, the total costs within each district were related to the number of dwellings exposed to an equivalent outdoor noise level above 55 dB(A).

Cost-effectiveness We simply calculated the indicators of cost-effectiveness as the relation between effects (EI-E 5 as described above) and the annual cost per dwelling.

3 RESULTS 3.1 T R E N D development in the study areas

The TREND will give improvements, but will not solve the traffic noise problems As shown in Table 3, without special measures we can expect a certain improvement in noise conditions towards the year 2000. The effect of increased traffic will in most cases be more than offset by the improvements in vehicle emissions. Reductions in the population in existing houses will also reduce the number of people annoyed by traffic noise in the study areas. Nevertheless, there will still be substantial traffic noise problems left in the year 2000, if no new measures are put into effect. Abatement measures are particularly needed in the four most centrally located districts, and in the area along the main road into Harstad (area 32). Two of the districts in Kristiansand (areas 23 and 24) are mainly in the 'grey noise zone' between 65 and 55 dB(A) outdoors. In these areas, abatement measures such as noise screens or insulation are only needed in the long term if the noise climate requirements are very strict. 3.2 Individual measures in the study areas

Significant variations in the cost-effectiveness of different measures in different types of areas The analysis showed that the cost-effectiveness of different traffic noise abatement measures varies significantly:

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TABLE 3 Calculated Proportions of Dwellings and Inhabitants Exposed to Traffic Noise in the Seven Study Areas in 1984 and in 2000, Without New Noise Abatement Measures

Type of area

Inner parts of large towns

Study area (number)

Griinerlokka/Sofienberg in Oslo (11) Dronningensgt etc. in Kristiansand (21)

Percentage of dwellings over 55 dB(A)

Percentage of inhabitants "very annoyed'

1984

2000 TREND

1984

2000 TREND

75

66

21

16

100

87

26

21

84

79

32

28

45

42

12

12

94

62

20

15

Inner parts of small towns

Skolegata/St Olavsgt in Harstad (31)

Large residential areas with multi-storey buildings

Oddernesveien/Osterveien in Kristiansand (22) Mollevannsveien in Kristiansand (23)

Residential areas with detached and semi-detached houses

Vestheia in Kristiansand (24)

48

57

12

12

Ribbon, development, low-density

Innfart sor in Harstad (32)

97

96

27

24

The effects from stricter regulations of motor vehicle noise were relatively high in all areas, when compared with other measures. The benefits increase with the density o f population in the areas. This indicates that some sort of geographical differentiation of vehicle noise regulation and/or vehicle taxes could be desirable, although difficult to carry out in practice. (b) Also, for other abatement measures, one could conclude that actions taken in central areas of larger towns are likely to be more costeffective than the same measures in other types of area. This is due to higher population densities, smaller dwellings and a less satisfactory traffic environment today. (c) Traffic management and local noise requirements for buses also came out as exceptionally cost-effective in the areas where they are applicable. Area traffic management schemes can very effectively be (a)

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159

combined with noise insulation of buildings along the main streets that cannot be relieved of traffic. The positive effects of traffic management are particularly well documented in the study district in Oslo, where we made a complete before (1974) and after (1984) study. (d) Building insulation is most effective in relation to costs when priority is given to the most heavily exposed houses. However, the costeffectiveness of noise insulation did not seem particularly sensitive to the indoor noise goals between 30 and 40 dB(A). The costs naturally depend on the ambitions of noise abatement goals. (e) Extensive use of noise screens is not very cost-effective. Considered as a noise abatement measure only, the building of new major roads, bypasses and tunnels in urban areas also proved to have little costeffectiveness. (f) Low-noise road surfaces seem to be more cost-effective than noise barriers, and in some cases also more effective than other means where driving speeds exceed some 60 km/h. However, because of little practical experience of costs etc., the conclusions are preliminary. A summary of some of the results is given in Table 4. In conclusion, noise abatement of vehicles turned out clearly to be more cost-effective than building insulation, as far as indoor noise climate and disturbance is concerned. In addition, quieter vehicles reduce outdoor noise and give noise reductions below the levels where specific actions are considered. Stricter vehicle noise regulations should therefore be given high priority in noise abatement. Both insulation of buildings and stricter noise regulations for vehicles will, under Norwegian conditions, save energy, if inhabitants and motorists do not significantly change their behaviour. For the Highways Authorities in particular, it is important to note that area traffic management and low-noise road surfaces proved to be more cost-effective abatement measures than noise barriers and the building of new urban main roads.

3.3 National estimates The costs and effects o f different combinations o f measures and noise abatement goals were estimated for the study areas and extended to the whole country The results from the study areas were used in an attempt to answer two i m p o r t a n t questions concerning a national traffic noise abatement programme.

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TABLE 4 Cost-Effectiveness of Local Noise Reduction Measures in the Study Areas: Reduction in the Number of Inhabitants 'Very Annoyed' per Million NOK Annually Spent 1986-2000~the Intervals Indicate Variations Between Areas and Noise Situations (1990-2000) Measure

Type q/area Inner parts

Inner parts

Ribbon

o['large

t~[ small

development, low-density (one area)

towns

(two areas)

Stricter noise regulations for vehicles

230-800

Local bus requirements

140660

Large residential Residential areas with areas with towns multi-storey detached and lone a r e a ) b u i M i n g s semi-detached (two areas) houses (one area) 100

Noise barriers, maximum use Noise insulation, all dwellings above 35 dB(A) indoors down to 30 dB(A) By-pass tunnel

70-110

60

20-80

10

10-20

20-50

30

50-70

160-290

20-40

0 (one area)

Low-noise road surface

(1)

80

40 (one area)

New main road (existing alignment)

Area traffic management: Extensive changes (1974-84) Smaller changes (future possibility)

50-90

130-200

650 (one area) 1~150

40

What is the most cost-effective way of reaching either of the following goals for the year 2000? Alternative 1: All dwellings should have traffic noise inside the house reduced to 35 d B ( A ) or less, and/or 65 dB(A) outside. Alternative 2: All dwellings should have traffic noise inside the house reduced to 30 d B ( A ) or less, and/or 60 dB(A) outside.

(2)

What are the national costs of different combinations of measures likely to be?

We constructed different 'packages' of measures that satisfied the alternative goals in various ways in the seven study districts. Only the most important noise abatement measures on a national level were considered: (a) (b) (c)

stricter noise regulation of motor vehicles; sound insulation of buildings, in all areas; noise barriers, in those areas and places where they were both possible and necessary in order to reach the goals.

Traffic noise abatement measures

161

None of the study areas were in rural districts, so special estimates had to be made for those parts of the country. Due to limited information about the present situation in rural areas, we were not able to estimate the likely effects of low-noise road surfaces on a national level. The main results from the national estimates are given in Table 5. The necessary investments in the period 1986-2000 were estimated as 76 million N O K per year, if no existing dwellings in Norway are to have an indoor noise level above 35 dB(A) by the year 2000. With the same goal, the investment can be substantially reduced if motor vehicles are improved in accordance with the assumed effects of stricter noise limits. The estimates indicate that the annual investment can be reduced to only 19 million NOK. If the acceptable noise level inside dwellings is reduced from 35 dB(A) to 30dB(A), the investments in insulation must be raised 5-7 times. With stricter noise regulations for vehicles the investments needed for building insulation were estimated to 140-150 million N O K per year. Without stricter regulations, the necessary investment with the goal of 30 dB(A) will be 350-400 million N O K per year. These levels of investment may be compared with the State's revenue from motoring taxes, which were some 10000 million N O K in 1984. If our main concern is the reduction of general annoyance from road traffic noise, the study shows that the abatement programmes which combine stricter vehicle noise limits with building insulation are most efficient. The 'packages' which include noise barriers are less efficient than those with insulation only.

5 DISCUSSION 5.1 Choice of noise descriptions and measures studied The results from this study are inevitably strongly influenced by its particular basis; indoor and urban noise situations. With more emphasis on outdoor and highway conditions, the results would not have been so much in favour of motor, transmission and exhaust noise reduction, and tyre/road noise would have to be considered. This relation is illustrated in Fig. 5. The results presented in this paper are all related to equivalent noise level (Leq) and the special annoyance description in Fig. 1. This indicator is 3-4 times more sensitive to alterations in percent heavy vehicles than a purely Leq-based description. There are no important findings related to restrictions on heavy traffic, and possible restrictions of this kind are few in Norwegian communities due to the small available choice of alternative

TABLE 5

No dwellings above 35 dB(A) indoors and/or 65 dB(A) outdoors

Goalto be reached in year 2000

(1) Noise insulation: all dwellings above 35 dB(A) indoors reduced to under 35 dB(A)

(1) Stricter noise regulation for vehicles (2) Noise insulation: all dwellings then above 35 dB(A) indoors reduced to under 35 dB(A)

A35

B35

Alternative noise abatement programmes

m

19

76

Annual investment needed (million NO K/year)

198

45

Total annual cost in 1984 (million NOK/year)

443

225

Cost-effectiveness: reduction o f the number o f people 'very' annoyed per million NOK annually spent on the programme 1986-2000

Estimated Costsand Cost-E~ctivenessofSix Alternative Traffic Noise AbatementProgrammes ~ r Norway198~2000

e~

t-3

No dwellings above 30 dB(A) indoors and/or 60 dB(A) outdoors

(1) Stricter noise regulations for vehicles (2) Noise insulation: all dwellings then above 30dB(A) reduced to under 30dB(A)

(1) Noise barriers where possible and noise outside house above 60dB(A) (2) Noise insulation: all dwellings then above 30dB(A) reduced to under 30dB(A)

B30

C30

(2) Noise barriers where possible and outside house above 60 dB(A) (3) Noise insulation: all dwellings then above 30dB(A) reduced to under 30dB(A)

D30 (1) Stricter noise regulations for vehicles

(1) Noise insulation: all dwellings above 30dB(A) reduced to under 30dB(A)

A30

t t 118

281

142

354

345

567

274

223

298

89

393

278

O~

164

G. Nielsen, S. Solberg

routes. Thus, the acoustical problem description is not very different from a pure-Leq description. The model for sleep disturbance is to some extent controversial, as the disturbance is defined as zero at indoor peak levels of 50 dB(A) or less. The analysis of cost-effectiveness was based on the annoyance indicator (Fig. 1). However, the other noise effect indicators gave similar results as far as the ranking of different measures' cost-effectiveness was concerned. The obvious exceptions were that noise insulation, of course, does not affect outdoor noise levels, and noise barriers leave noise on streets and pavements unchanged. The assumption about closed windows is not in accordance with people's behaviour, but we considered it a necessary simplification. Field studies in Oslo 11 have indicated that some 38% of people with sleeping rooms facing main streets have their windows open during summer nights. In comparison, the percentage was some 73% for people sleeping on the 'silent' side of the buildings. The closed-window simplification thus underestimates the absolute size of the noise problem in the study districts and exaggerates the benefit of noise insulation. We only considered the open-surface type of low-noise roads and not poro-elastic types. The possible reduction of engine noise from surface absorption is not included. Altogether, low-noise road surface was the measure studied about which the most uncertain assumptions about both effects and costs had to be made. Our conclusions about this measure are therefore very preliminary, but indicate that more research should be directed towards this aspect of noise abatement. A more fundamental question can be raised concerning the relevance of the dose-response relationships assumed in Fig. 1-3. A review of the literature (including Schultz 5) on the relationship between physical noise indicators and peoples' response to traffic noise is concluded that: There is no conclusive evidence of a direct cause--effect relationship between physical noise level and the annoyance or disturbance that people experience. (b) Dose-response curves found in one noise situation cannot automatically be applied in a different situation (different place, country, group of people, local context, etc.). (c) The relationship between noise and response found in a static situation is not applicable when forecasting the response effects of specific measures to reduce noise levels. (a)

Therefore, the effect measurements used in this study should only be treated as rough indicators, and not as direct forecasts of the noise reduction benefits.

Traffic noise abatement measures

165

For the further development and refinement of noise abatement policies, it is necessary to make more comparative studies of both noise response and the broader effects of various abatement measures in different noise situations (see section 5.3).

5.2 Few study areas and special Norwegian conditions The general conclusions and national estimates are, no doubt, rather bold, being based on detailed studies in only seven small urban districts. However, study results were fairly consistent between areas, very different types of development and noise situations in Norway were covered, and the results seem to be in accordance with the common sense judgements of Norwegian experts. The national estimates are the most uncertain part of the study, due to the limited quality of data about the present traffic noise situation in Norway. For international comparisons, it may be of interest to stress a few points about special Norwegian conditions affecting cost-effectiveness, and priorities between different abatement measures: (1) Although Norway is not among the most densely built-up countries, due to topography and the character of urban development, a high proportion of Norwegians live close to a main road with through traffic. The practical possibilities of measures such as re-routing of heavy vehicles are few, and the costs of building new by-pass roads are often very high in Norwegian communities. (2) The cold and long Norwegian winter means that noise insulation, which at the same time gives heat insulation and energy savings, is more cost-effective than in countries with a milder climate. The energy saving for the noise insulation (noise exposed side only) of a 1 0 0 m 2 flat is in region of 300-3000 kWh per year, depending on initial status and level of insulation. An energy loss of 700 kWh per year from controlled, silent ventilation is included in this estimate. The cold climate also reduces the likelihood of people having the windows open. The energy savings from encapsulated engines (section 2-5) will also be less marked in a more temperate climate. (3) In Norway there are few high-speed roads in urban areas, and speed limits are generally more restrictive than in other countries (50 km/h in urban areas and 30 km/h in large parts of residential roads and streets). This means that more emphasis should be put on measures affecting traffic noise at low speeds in Norway than in other countries.

G. Nielsen, S. Solberg

166

5.3 Other effects of noise abatement measures

The study was limited to noise effects and direct costs (including energy effects). Most traffic noise abatement measures also have other effects. For instance, noise barriers may have undesirable visual and aesthetic consequences and cause severance, but also have more positive safety and environmental effects. Traffic management measures are very often desirable from a traffic safety and traffic speed point of view, and noise reduction in protected areas is often an additional reason for putting such measures into operation. For the development of policy such costs and effects are important. We will claim that, more often than not, these other considerations tend to confirm our policy conclusions.

6 POLICY R E C O M M E N D A T I O N S Our conclusion is:

Priority should be given to actions in central urban areas, stricter regulation of vehicles, area traffic management, low-noise road surfaces, and insulation of the most exposed dwellings. In order to have the greatest possible reduction of 'traffic noise problems' in relation to the money which is spent on noise abatement measures in Norway, the following should be given priority: (1) Stricter noise emission limits for motor vehicles, so that the present positive trend will continue. It is also important to note that this is the only measure where the costs are directly covered by the 'polluters', the motorists. (2) Area traffic management wherever feasible, so that traffic noise problems can be concentrated to fewer streets and highways where insulation etc. may be carried out. (3) The development of low-noise road surfaces on roads with speed limits of 60-70 km/h or more, especially in order to avoid the setting up of noise barriers, etc., in less densely developed areas, and because the effects of improved vehicles will not be so significant at these driving conditions as in urban traffic. (4) Noise insulation of buildings where today's noise levels are very high, and where alternative measures are impossible or less cost-effective. (5) The regulation of heavy lorry routes and increased use of low-noise buses where possible in urban districts.

Traffic noise abatement measures

(6)

167

Measures in the most densely populated urban areas where the conflicts between traffic and the environment are particularly severe.

Stricter emission limits and low-noise road surfaces will take some years to have significant effects on the traffic noise problems. Therefore, it is important to give economic priority to measures which can be quickly carried out. This will give the greatest possible benefit before the more longterm measures start to have an effect. These conclusions are more or less built into the proposed traffic noise abatement programme of the N P C A in Norway of 1985.17

A C K N O W L E D G E M ENTS The paper is based on the authors' work in 1983-5 on a study project made by the Institute of Transport Economics, with K I L D E as acoustic consultant. 1 At the Institute, Audun Harstad and Peter Christensen were responsible for the computer programming and data analyses, and Odd I Larsen contributed to the methodology of the economic evaluation. The authors were responsible for the study design, fieldwork, analysis and final reports of the study. The project was carried out in close co-operation with the local authorities in the cities of Oslo, Kristiansand and Harstad: they supplied the basic data from the study districts. The study was followed by an advisory committee of officials from the Norwegian State Pollution Control Authority and The National Roads Directorate. The study was financed by these two authorities and by the Institute of Transport Economics.

REFERENCES 1. Nielsen, G. & Solberg, S. Kostnader og effekter av tiltak mot vegtrafikkstoy-grunnlagfor et nasjonalt handlingsprogram (Costs and Effects of Traffic Noise Abatement Measures--Basis for a National Programme). Institute of Transport Economics (TOI), Oslo, 1985. 2. Kajland, A., Cost-Effectiveness for Traffic Noise Abatement. A compilation made of a seminar arranged by 'The Nordic Noise Group' (NBG), Stockholm, 1983. 3. Nielsen, G., Vegtrafikkstoy 1970-2000---et fors~k p~ framskriving av trafikkstoyproblemene i Norge (Road Traffic Noise in Norway 1970-2000). Institute of Transport Economics (TOI), Oslo, 1985. 4. Statens Naturv~rdsverk, Beriikningsmodell f6r viigtrafikbuller. Stockholm, 1979.

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5. Schultz, T. J. Synthesis of social surveys on noise annoyance. J.Acoust. Soc. Am., 64 (1978), 377-405. 6. Langdon, F. J., The effect of road traffic noise in residential areas: noise nuisance caused by road traffic in residential areas: part II. J. Sound Vib., 47 (1976), 265-82. 7. Eberhardt, J. L. & Akselsson, K. R., The Disturbance by Road Traffic Noise of the Sleep of Young and Elderly Males as Recorded in the Home. Lunds University, Lund, 1982. 8. Houtgast, T., The effect of ambient noise on speech intelligibility in class rooms. Appl. Acoust., 14 (1981), 15-25. 9. Arntzen, E. et aL, Vegtrafikkstoy i bymiljo (Urban Traffic Noise). Oslo City Health Department, Oslo, 1982. 10. Solberg, S., Hagen, R. & Ommundsen, R., Perceived noise reduction and secondary effects from the use of building insulation and barriers. Internoise 83 Proceedings, 1983, pp. 667-70. 11. Gjestvang, O., Krokan, A. & Solberg, S. Opplevelse av tungtrafikkstoy og andre ulemper fra trafikk i 10 Oslo-omrhder (Subjective Response to Heavy Traffic Noise and other Nuisances from Road Traffic in 10 Areas in Oslo). Oslo City Health Department, 1983. 12. Solberg, S., Effects of road traffic noise: description of effectiveness from noise abatement measures. FASE 84 Proceedings, 1984, pp. 245-8. 13. Central Bureau of Statistics of Norway, Eie og bruk av personbil 1980 (Private Motoring 1980). Kongsvinger, Oslo, 1983. 14. Solberg, S., Forutsetninger om stoyemisjon fra trafikk 1974-2000 (Assumption on Noise Emission from Road Traffic 1974-2000). KILDE report 115, Voss, 1984. 15. Nielsen, G., Traffic noise in Norway 1970-2000. Internoise85 Proceedings, 1985, pp. 141-4. Tb No. 39, Bundesanstalt fiir Arbeitsschutz, Dortmund. 16. Soiberg, S. & Nielsen, G., A model study on strategies for traffic noise abatement in built-up areas in Norway. Internoise 85 Proceedings, 1985, pp. 149-52. Tb No. 39, Bundesanstalt fiir Arbeitsschutz, Dortmund. 17. Norwegian State Pollution Control Authority, Proposal for a Programme of Action to Reduce Noise from Road Traffic (English summary). Oslo, 1985. 18. Hjorthol, R., Stoy fra vegtrafikk: virkninger p~ befolkningen (Road Traffic Noise: effects on People). Notat 773. Institute of Transport Economics (TOI), Oslo, 1986.