Journal of Sound and Vibration (1977) 51(3), 343-351

R A I L W A Y NOISE A N N O Y A N C E IN R E S I D E N T I A L AREAS:

C U R R E N T FIN DINGS A N D S U G G E S T I O N S F O R F U T U R E

R E S E A R C H

J. M. FIELDS

Department of Social Statistics, Unicersity of Southampton, Southampton S095NH, England

(Receired 2 December 1976)

Five published studies of railway noise annoyance in residential areas are reviewed�9 All the studies find that annoyance increases with railway noise levels and number of train passages. Two studies showed reactions to railway and road traffic noise as not strikingly different but the five studies do not agree on the actual relation between railway noise and annoyance. The apparent differences between the studies' findings may be due to genuine differences in annoyance reactions or to differences in study designs or measurement techniques. Some methods for ensuring more comparable results are suggested in the areas of sample design, questionnaire construction, observational data, and reporting of results.

1. INTRODUCTION

Noise is a subject of concern because of a social and psychological phenomenon: the fact that humans notice and complain about noise generally and railway noise in particular. This paper seeks to further the study of this phenomenon by first reviewing findings from the existing surveys of human response to railway noise and by then pointing to ways in which studies can be designed to better contribute to a body of internationally useful knowledge about human response to railway noise.

Humans are exposed to railway noise in a number of different situations: as workers on trains or along the lines, as passengers on trains or on platforms, and as community members at work, at play, or at home. Though all of these situations are of importance, the discussion here is confined to the responses of residents along railway lines as they'can be measured in social surveys.

The most crucial facts about five railway noise social surveys and noise measurement studies are summarized in Table 1. Only the first three studies have been extensively enough

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documented (at least ifi English) for lengthy discussion here.t Several additional surveys are now being planned and executed including our own at the Institute of Sound and Vibration Research. Work is progressing on a Swedish railway noise survey. There are plans for a combined railway and road traffic noise survey in Britain.

2. FINDINGS FROM THE SOCIAL SURVEYS

2.1. DESCRIBING THE DISTURBANCES

The contrast between the general lack of organized protest about railway operations (especially long established ones) and the high measured levels of railway noise has led some observers to suggest that people may be unaffected by railway noise. This is not the case.

t The Japanese survey has been more extensively documented in the Japanese language. Hopefully no injustice has been done to the original studies through the use of the shorter reports in English.

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RAILWAY NOISE ANNOYANCE 345

Clearly at high noise levels with frequent train movements, railway noise can disturb people's activities and be annoying. The most extreme finding is that 98 ~o of the respondents in the highest noise level Paris area sites (Le~ of 76 to 80 dB(A)) report that watching television is disturbed by trains when their windows are open [I]. AI; the same noise level 22 ~ of the sample chose the highest annoyance response on a five point scale ("very discontented") while no respondent chose the lowest annoyance response ("very satisfied"). By way of contrast, at a low noise level (69 dB(A) peak) along the New Tokaido line in the Shinkansen study only I0 Yo of the respondents said that their conversations were interfered with [2].

Listening to television (not picture flicker) appears to be the activity most easily disturbed by railway noise in three and possibly all four of the surveys for which evidence is available. Interference with conversation is the next most easily disturbed activity in these surveys. Such activities as reading, relaxing, and sleeping are apparently not as easily disturbed.

Residents do find aspects of the railways other than the rolling noise from through trains to be annoying. Aubree [1] reports that about half of the Paris area respondents mentioned some "dominant noise" in the noise of the train other than that of various rolling noises. The only study which specifically asked about maintenance noise found that a third of the respondents "strongly" agreed that "The noise from the railway is particularly bad when they are doing repairs or maintenance work on the line" [3]. A variety ofnon-noise inconveniences from having a railway in the area are reported by 61 ~ of the Paris area sample. In the only study where vibration annoyance has been explicitly measured, the Shinkansen survey found that over 60 ~o of the respondents living at less than 60 m report "house vibration" [2]. Interference with television pictures is also of potential importance. Of the respondents in the central England survey who said that the noise made "it hard to hear TV or radio", 40Yo went on to report that this was "because the train makes the sound and picture fade" [3]. In the only survey in which TV picture flicker was specifically singled out, over half the respondents reported interference at 110 m [2]. The above findings are reported only to suggest that aspects of railways other than noise from through trains may have a considerable effect on residents' annoyance.

These studies cannot give insight into the relative importance of the various other sources of annoyance because (1) the non-probability designs do not provide estimates of the percent of the residents over a large area who experience each type of annoyance and (2) the question- naires did not contain a ranking of the relative importance of the different noise sources.

2.2. CAUSES OF ANNOYANCE--RAILWAY NOISE LEVEL

In accord with common sense, the most important single determinant of annoyance with railway noise is the amount of railway noise. The questio~ as to what descriptor should be used for the noise has been considered in each study. The studies all suggest that, as for air- craft noise, annoyance and activity interference increase with both the loudness and number or duration of the events experienced (see Figure 1). In the Paris area survey Leq correlates some- what more highly with annoyance measures than does either traffic volume or a weighted average of peak level, L,, [1].I Similarly the Shinkansen data indicate that as noise levels increase within two number of trains categories (80 and 200 trains per day) annoyance also increases [2]. No evidence convincingly suggests that one equation for combining noise levels and number of events is any more highly related to annoyance than is another. The Sendai City data for four non-Shinkansen lines suggest that Leq, N N I and IVECPNL do not signi- ficantly differ from each other [4]. In the Paris area survey Leq correlates just as highly as do

t L,. = lOlog(~, n,c~/'fl n~T~), where n, is the number of trains of type i, T~ is the time during which the train noise level is within 10 dB of the maximum level for the ith train, and ff~ is l~ico-joules/m z for the ith train.

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two less widely used measures'{'. In fact, as Dent and Smith [5] note, the low correlations human annoyance separately with peak noise levels and with numbers of events mean th~ any index combining these two basic types of noise descriptors cannot have a very high co: relation with annoyance. From this it also follows that for moderate sized samples an differences in the correlations of annoyance with reasonable noise indices based on noi,~ levels and numbers of events are likely to be so insignificant as to easily arise as a result c sampling variability. Given the somewhat arbitrary nature of the choice of the descriptor, is fortunate that some of the well documented railway studies share a single measure, 24-hot Lea dB(A).

2.3. C A U S E S O F A N N O Y A N C E - - - - O T H E R F A C T O R S

Annoyance with the railway noise is affected by both individual characteristics ofrespon~ ents and by characteristics of their dwellings and areas. The Shinkansen survey reports th~ the visibility of the railway has an effect on annoyance beyond that due to the noise level itsel In the Paris area survey, the results for one annoyance question show that over 30 Yo mol people were annoyed at the same noise level when all the rooms in their home faced the railwa, Ambient noise levels may also be of importance. The general railway annoyance inde developed in the Paris area study is correlated with ambient noise levels, though the fact th~ ambient noise levels and railway noise levels are correlated makes the interpretation unclea~ Walters suggests that ambient noise levels in a block of fiats may have increased annoyanc responses in one of his areas [3].

It is certainly possible that the type oftrains or the railway's characteristics affect annoyanca The Sendai City survey found that even after controlling for Leq reactions were different alon the four different types of routes [4]. Inspection of Table 1 shows that research thus far ha been heavily concentrated on one general type of railway line: electrified lines with hear traffic dominated by passenger trains. Other types of lines deserve equally close attentiot Many people live in completely different railway environments. For the Sendai City line~ relatively higher levels of complaints were said to occur along the freight only line. ~t

Characteristics of t.he area in which people live may affect annoyance with the noise, h the Shinkansen study residents along a recently opened (four months old) Shinkansen lin~ were found to be much more annoyed than those along an older line (eight years old) [2] Aubree suggests that in the Paris area the respondents' evaluation of the neighbourhood an~ thus perhaps even the objective characteristics of the neighbourhood environment itself ca1 affect the human response to the railway noise [1 ].

"j" One measure combined L,,, and the logarithm of the traffic volume. The other measure combined Lm an the logarithm of the total duration of train passages.

:~ Personal communication with T. Nimura.

RAILWAY NOISE ANNOYANCE 347

As in all environmental noise surveys there is a great deal of variability in individual response that cannot be attributed to the noise environment itself. Though much of the un- ,explained variation may be due to the measurement problems and unmeasured variables, some of it might be due to factors measured in studies. All the studies have considered the possibility that some basic demographic factors may affect annoyance. However, no study has reported a statistically significant relationship between annoyance and any of the basic demographic variables ofage, sex, occupation, social status, or length of residence in the area.

The Paris area study is the only study that reports upon possible attitudinal influences. The study found that attitudes towards the railways in general are correlated with annoyance. Though these attitudes may not actually cause annoyance, the possible importance of such variables is indicated by the fact that Aubree's prediction equation can require adjustments for as much as 20 dB depending upon the exposure of the dwelling to the railway and the scores on three attitudinal variables.

3. UNANSWERED QUESTIONS

3.1. IS RAILWAY NOISE AN EXTENSIVE PROBLEM .9

None of the studies directly addresses the problem of how many people in the surveyed ,city or country are exposed to different levels of railway noise or indeed of whether or not rail- way noise is felt to be a problem by large numbers of any area's inhabitants. Such information ,could be of considerable policy interest since, if only a limited number of people were affected and they were located in only a few areas, it' might be more economical to use barriers to xeduce noise levels, whereas if annoyance were qu!te widely spread along the route, it might ~ge more economical to modify the trains themselves. The extent of the railway noise problem for particular countries obviously depends upon at least the amount ofrailway line in densely [populated urban areas and the propagation of noise within those areas. In the only set of data ~,hich could assign levels of confidence to estimates of the percent of the population annoyed, it was estimated that 35 ~o of the population of England would report they could hear railway aaoise, 2 ~o are bothered by it and about I ~o find that railway noise is the biggest noise nuisance ahey can hear when at home [6].

3.2. WtlAT IS TIlE RELATIONSHIP BETWEEN RAIL~VAY NOISE AND ANNOYANCE.9

The crucial question and indeed purpose of the entire social survey-noise study exercise is to discover the relationship or relationships between noise levels and human response. The results for three surveys which have presented the relationship between 24-hourLeq and roughly comparable measures of disturbance when listening to television are shown in Figure 1.t The Sendai City survey, of regular railway lines and the Japan Environmental Agency Shinkansen survey show slightly different slopes and intercepts. The authors do not indicate whether there is a statistically significant difference between the two surveys' results. The results for the Paris area survey are strikingly different. The Sendal City respondents report

"f For the Paris area study the definition of disturbance as it relates to television is "being able to watch television without being disturbed by the train noise" with the windows open. For the Sendai City study the definition of television listening disturbance is the percent of respondents who say their television listening is at least "sometimes" or "occasionally" (the exact wording depends on the translation) interfered with by the noise as opposed to being no more than "rarely" or "a little" disturbed by the noise. Thus the questions are phrased quite differently. It is not clear whether one question makes it easier for a respondent to report TV interference than does the other. The differences between the two studies may be partly due to the differences in the questions used. The Sendai City survey asks about both television and radio disturbance in a single question. The Paris area survey uses separate questions. Only the television results are used here, since it is felt that they are more relevant. Although the 24-hour Leq is used in all surveys, it should be noted that the Japanese railways were closed from 24.00 to 6.00 a.m.

348 J.M. FIELDS

the same amount of disturbance at about 15 dB(A) Lcq lower than do the Paris Area respond. ents. The importance of this difference is perhaps more striking if one notices that a noise control officer who used the Paris area data to set a noise limit where only 50 ~o of the people were'disturbed (thus choosing 66 Leq) would in fact be setting a level such that over 85 Yo were annoyed if the population were similar to the Sendai City respondents. The statement in th~ Paris area survey that the relationship between noise and percent annoyed is linear can obvi. ously not be the case for the Sendai City respondents over the whole range of values from, 40 to 80 dB(A) Le~.

Why are the relationships so different? It could be the fact that different measures of' annoyance are used, or thai the surveys are in different countries, that dwellings vary in their sound attenuating qualities, that different background noise levels are present, that different percentages of respondents in the surveys could see the railway lines, that there is very little overlap in the noise zones surveyed, that the high proportion ofhousewives in the Sendai City survey biased the results, or that any number of unreported factors were different in the two surveys. In short, the results do not enable us confidently to make comparative statements about railway noise annoyance in the two countries.

We cannot glibly assume that surveys merely show that Japanese are more sensitive to noise than are Europeans. Figure 2 compares the relationship between NNI and annoyance for Heathrow in 1961 [7] and for the new Tokaido Shinkansen line. This time the European survey shows greater annoyance at most noise levels. Once again the results suggest quite different noise to annoyance relationships.

The studies contain evidence which is relevant to the question as ;o whether railway or road traffic noise is more annoying. Figure 3 shows that residents' reactions to road traffic in Sendai City [8] were quite similar to and, over most noise levels, intermediate between residents' reactions to railway noise in Sendai City and t o the noise of the Shinkansen.

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t The Paris area findings are compared with the Sendal City regular lines and not the Japan Environmental Agency Shinkansen line findings because the railways would seem to be more similar.

RAILWAY NOISE ANNOYANCE 349

'Though it has been concluded from a French survey that train noise can be 5 dB higher than ~oad traffic noise before the same level of annoyance is reached [9], on reflection it would seem Ithat such a small difference is of doubtful statistical significance with these moderate sized ~amples. In fact that difference of 5 dB is about the same size as the difference between the reactions to the Shinkansen and regular lines in the Japanese surveys. On the basis of these 6tudies it appears that the reactions to road traffic and railway noise are broadly similar.

With respect to the major question about the relationship between noise and annoyance [however, the only consistent results for all these surveys is that annoyance increases with tincreasing amounts of noise. We cannot even state whether the relationship is linear. In view of the results of these surveys it must also be apparent that there is no scientific support for aransferring the acceptability levels which have been set on the basis of one survey to other ~:onditions. One should suspect this from the diverse recommendations of acceptable levels: 24-hour L~+ of 72 dB(A) [1, Aubree 1971], 70 riB(A) peak in Japan [2, Nimura et al. 1975], 80 dB(A) peak in 1973 by the Japan Environmental Agency [10, Miyaji 1973], and 70 to 75 dB(A) peak in 1975 by the Japan Environmental Agency [11, Hashimoto 1975: 729].

4. CREATING COMPARATIVE DATA

The incomparable results should be no surprise. Different questionnaires were used. The very fact that there are many factors other than the noise level itself that affect noise reactions suggests the possibility, as McKennell notes [12], that areas may differ with respect to these factors and thus the annoyance relationships within the areas must differ. The methods for generating better comparative data have been well developed for social science data generally and statisticians can apply them in a fairly straightforward manner to the case of railway surveys. In considering the railway case specifically, a design for a nationwide survey has /~een described elsewhere [13]. The greatest comparability between surveys can only be ~achieved through extensive consultation at the planning stages. However, some advances can ,be made by designing statistically sound representative probability samples of the study population and by using the following procedures.

1. Selection of sample. Statistically sound methods are used to draw a random sample which gives all residents near railways a known (possible unequal) chance of being included in ~he sample.'~ The population is grouped into analytically important strata with noise levels ~ i n g one of the defining characteristics. A wide range of noise levels is included. At least two study sites are drawn from each stratum.

2. Descripti•n •f sites. Regard•ess •fh•wthe samp•e is se•ected a•• p•ssib•y re•evant features :of the study sites are noted. Such features should include information both about the railway ~--visibility, number of trains, types of trains, time of day train passages, non-through train ~'ailway noises, non-noise railway nuisances, speed of trains, and presence of cutting or iembankment--and about neighbourhood conditions--presence and magnitude of other noise ~sources, amenities in area, degree of urbanisation, description of environmental quality.

1 Unfortunate consequences flow from one strategy aimed at ensuring comparability by studying reactions tonly in areas of a certain very restricted type (e.g., residents in the first row of houses with a clear view of a ~usy railway line where no other background noise is present). In this case the survey results can only be applied lo similar areas, and thus will apply to only a small proportion of all the people exposed to railway noise. If the investigator goes even further towards a purposive sample and chooses among all potential sites with a non-random method, then the results cannot be statistically evaluated because (among other reasons) there is no way of ensuring that the criteria for the investigators' final decision do not further restrict the type of area for which the results will be applicable. For example, if an investigator, as is not uncommon, only chooses ~sites within convenient travel distance of his institution, then he is limiting the study to particular climatic :onditions and to the social conditions ~vhich are present in that region. A better strategy for ensuring com- xarability of study sites is to select many broadly different study sites and then carefully describe the sites in malytically useful terms.

350 J.M. FIELDS

3. Questiom~aire construction. The social survey questionnaire is designed to be as com- parable as possible to pre-existing surveys of noise. This is most important for the central measures of annoyance. Though strict comparability of questionnaires is only ensured if there is co-ordinated planning and translation of questions, it is possible to greatly increase the comparability of questionnaires if each includes a basic 7-10 point rating scale of the noise (ranging from satisfactory to definitely unsatisfactory) and measures of interference with at least conversation, radio and television listening (not visual interference), and sleep.

4. Reporth~g ofresu#s. Results are reported so that readers will know exactly what variables did and did not affect annoyance. The exact definition of all variables such as "house type" which may vary from country to country, or from study to study, are defined whether or not they are found to be of importance in the particular study. Relationships between noise levels and annoyance are either presented graphically or in terms of percentage scores. This is done both for the total sample and separately for any additional variables which affect annoyance. Such a procedure is preferable to the use of correlation or partial correlation coefficients since the latter only measure the goodness of fit to a linear relationship and not the actual nature of the relationship. All aspects of the study design are described in the final report including the method of selecting sites, houses and respondents within houses, the criteria for excluding sites, and the time of year of the social survey.

5. CONCLUSION

From the five studies reviewed in this paper several useful generalizations can be made. Some people do find railway noise annoying. Television listening and conversation are more often reported to be interfered with than are sleep, relaxing, or reading. Evidence also suggests that there are, at least in some cases, adverse reactions to railways and railway noise other than those generated by the noise from passing trains. There are reactions to non-noise aspects of the railway's presence including vibration and television picture interference. All studies have found that both peak levels and numbers of events affect annoyance levels. There is at least scattered evidence that annoyance is sometimes affected by ambient noise levels, visibility of the railway line, amount of time elapsed since the railway was built, and attitudes toward the neighbourhood, railway, and noise in general.

Though we have found that reactions to road traffic and railway noise are broadly similar within each particular group of investigators' data, we find that different investigators' findings about the basic railway noise annoyance relationship are inconsistent. More com- parable results might well emerge in future studies if there were co-ordinated planning. To ensure the comparability of results from diverse studies, careful attention must be taken so that sampling, observation, questionnaire construction and reporting are conducted in a more standardized manner.

REFERENCES

I. D. AUBREE 1973 (June) C.S.T.B. Nantes. Acoustical and sociological survey to define a scale of annoyance felt by people in their homes due to the noise of railway trains.

2. T. NXMURA, T. SONE, M. EBATA and H. MATSUMOTO 1975 Noise ControlEngineerhlg, 4-11. Noise problems with high speed railways in Japan.

3. D. WAL'rERS 1969 Proceedings of the Conference on Architectural Psychology, Un&ersity of Strathclyde, March 1969. Annoyance due to railway noise in residential areas.

4. M. KUMAGAI, S. KONO, T. SONE and T. NIMURA 1975 lnternoise 75. A consideration on the rating of train noise from ordinary railways.

5. 1966 Gor'ernment Social Sttr~'ey Report SS332. Second survey of aircraft noise annoyance around London (Heathrow) Airport. London: Her Majesty's Stationery Office.

6. S. D. SANDO and V. BATTY 1975 Social Trends 5, 64-69. Road traffic and the environment.

RAILWAY NOISE ANNOYANCE 351

7. A- C. McKENNELL 1963 Aircraft Noise Annoyance Around London (Heathrow) Airport. London: Central Office of Information, SS337.

8. A. SHIBUYA and S. TANGO 1975 Internoise 75, 425-428. Road traffic noise and community response in Sendai City.

9. P. GILBERT 1973 Institute of Acoustics Meeting, Southampton, Not'ember 1973. The effect of train noise on the environment.

10. K. MIYAJI 1973 July Railway Gazette International, 219-251. Noise control on the Shinkansen. 11. M. HASHXMOrO 1975 Internoise 75, 719-729. Present status of noise regulations in Japan. 12. A. C. McKENNELL 1973 Proceedings of the International Congress of Noise as a Public Health

Problem, Dubrovnik 1973 EPA 500/9-73-008 Washhlgton, D.C., 627-644. Pyschol-social factors in aircraft noise annoyance.

13. J. M. FIELDS, J. G. WALKER and J. LARGE 1976 Internoise 1976, 203-208. Designing a national study of railway noise in Great Britain.

14. Anon. (undated) Short report on the attitude survey of train noise along new Tokaido line. (Mimeograph.)