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Effects of road traffic noise on a residential community Quirt, J. D.

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Publisher’s version / Version de l'éditeur: https://doi.org/10.4224/40000592 Building Research Note, 1977-02

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EFFECTS OF ROAD TRAFFIC NOISE ON A RESIDENTIAL COMWWI"Y

by

J.D. Quirt

1. INTRODUCTION

In August 1976, as part of a continuing study of the effects of road and rail noise an residential areas, a study of the noise environment in the South Keys area of was undertaken. This area was chosen because of proposed changes in the road system which could be expected to produce changes in the noise pattern. This report, the "befo~e''portion of the study, includes a survey of existing noise and a prediction of future noise levels. An effort is made to relate these noise levels to widely accepted noise criteria, in order to provide a basis for evaluation of the environmental impact of the proposed development.

This report is subdivided into four sections. Section 2 introduces same of the relevant units for describing noise and some proposed standards for noise limits to get he^ with brief indications of their implications, A description of the equipment and procedures used in the noise survey and a swmnary of the results are contained in the Section 3. Section 4 contains some predictions of the changes in noise levels associated with changes in road use, and directly relates these to the criteria discussed in Section 2.

2. ENVIRONMENTAL NOTSE DESCRIPTION AND CRITERIA

2-1 Noise Units

A brief, very superficial description of the relevant units will be presented. More technical details and explanations may be found in the listed ~efesences,

Studies of environmental noise and the associated community response normally use the A-weighted sound level as the basic measure of noise intensity. The A-weighting causes the measure- ment system to respond to high- and low-pitched sounds in approximately the same way as does the human ear in judging loudness. More directly, A-weighted levels are found to correlate well with human assessment of the noisiness or annoyance associated with intrusive sounds.

The noise emitted by road traffic fluctuates with passing time, both qn the short time scale (as individual vehicles pass by] and on the longer scale (as for example if traffic volumes are smaller at night). In order to describe such noise, a measure called the "equivalent sound level" is commonly used. This is the level of a steady sound carrying the same energy as the time-varying sound during the specified time period. When assessing the environmental impact of traffic noise it is common to consider dayrime and nighttime periods separately. For purposes of this report the Daytime Sound Level (Ld) is the A-weighted equivalent sound level for the time period from 0700 to 2300 hours; the Nighttime Sound Level [h) is the A-weighted equivalent sound level from 2500 to 01700 hours.

Although both Ld and are of interest is assessing a noise climate, it is generally considered more convenient to have a sZLnglcnoise index to characterize a site. The Day-Night Average Sound Level (Ld,) developed by the U.S. Environmental Protection Agency is the A-weighted equivalent sound level for a 24-hour time period with a 10 dB correction added to the actual sound level during the nighttime hours. This correction to the nighttime level is justified by the increased sensitivity to noise at night when most people are sleeping (or trying to sleep). The nighttime period used for the exact definition of Ld, is from 2200 to 0700 hours. For purposes of this report, however, the values for the night and day periods indicated in the definitions of Ld and L,, will be used to obtain an approximate Ldn. The difference is negligible in most cases, and xhis permits comparison with the standards proposed by the Ministry of the Environment.

2.2 Typical Community Response

In order to make use of noise survey, one must establish the relationsllip between noise levels and human reaction to such noise levels. In recent years many large surveys have been made both in North America and in Europe to determine the typical. community reaction to intruding noise. An excellent summary of the results of these studies has been published ('1. Figure la, which was taken from (11, shows the data far one group of 55 communities which were studied. It is clear from the Figure that there is considerable variation in cornunity response and that prediction of this response simply on the basis of Ld, is not very reliable. The mean valve of outdoor Ldn associated with "no reaction1" is 55 dB; with f'viga~ous reaction", 72 dB. Much more reliable prediction of cormunity response is possible using the "Normalized Day-Night Level" which is obtained by adding to Ld, several corrections associated with the nature of the noise and the community. These corrections are listed in Table I, and Figure lb shows how the use of these correcrions reduces the scatter in the community response. It appears that the normalized outdoor Ld, provides a reasonably accurate assessment of the impact of an intruding noise on a community.

Some Recommended Environmental Noise Criteria

At this time very little legislation to protect the public from noise has been enacted. Recommendations for appropriate nois'e criteria have been proposed, however, by various government agencies, both in Canada and in the U.S.A.

Probably the most far reaching study of noise problems has been made by the U.S. Environmental Protection Agency. It identified an outdoor Ld, of 55 dB and an indoor Ld, of 45 dB as thc maximum levels consistent with "protecting publ~chealth and welfare with an adequate margin of safety." An extensive discussion of the reasons for this recommendation is given in Ref. (1). Note that an outdoor nonnalised Ld, of 55 dB corresponds to the community reaction category "no reaction, although noise is generally noticeable."

Within Ontario, essentially similar noise level limits for residential areas are recommended by the Ontario Ministry of the Environment. In the Model Municipal Noise Control By-Law (2) the sound level limits specified are Ld of 55 dB for outdoor recreation areas (45 dl3 for inside the house] and of SQ dB for outdoors (40 dB far indoor space intended for sleeping]. These values for Ld and L, correspond to an outdoor Q, limir af approximately 57 dB. The Ministry of the Environment recommends that new housing developments conform to these limits, although levels 5 dB higher are considered acceptable in cases where additional homes are being constructed in an existing community.

3. NOISE SURVEY IN SOUTH KEYS

Outdoor noise measurements were made for one or more days at each of several sites in the South Keys area during the period from 13 September to 8 October 1976. The noise was measured using a Metrosonics dB602 sound level analyzer and a Bruel E Kjaer Type 4145 microphone with Type 2619 preamplifier and Type UA0207 windscreen. Data were read out from the analyzc~after each 24-hour period using a Date1 DPP-7 digital printer interfaced to the Fietrosonics analyzer. The system calibration was checked before and after each measurement period, using a Bruel E Kjaer Type 4230 pistonphone. This equipment is almost completely automatic; the routine operations to obtain the daily printout of data were performed by householders in the South Keys area.

Tlle measurement sites were cIaosen to provide a representative crass-section of the noise environment in the various parts of the comity. The locations of tlre sites are shown in Figure 2 and a derailed description of the microphone locations is given in Table IT. Sites 5 and 4 were chosen to indicate typical noise levels near the middle of the community where traffic noise is minimal. The other sites were exposed to the noise fxom the more heavily-used roads around the periphery of the community.

The data from these measurements are shown in Figures 3a to 3f, and are summarized in Table TIT. Because the measurement system responds spuriously to rain or high winds, data from periods when such weather conditions might have distorted the results were discarded.

Scvcral features of the data obtained are noteworthy. With the exception of some of the data in Figure 3a, the sound levels shown in FiLgures 3a to 3f are the average equivalent sound pressure levels over four-hour periods. It can be seen fxom Figure 3a that while the use of shorter {one-hour) averaging periods shows more clearly the variations in noise level on that particular day, it also obscures the over-all trends in the data.

Several trends are evident. At all sites the noise level was significantly lower during the nighttime period (2300 hr to 0700 hr) than during the daytime. Secondly, the noise levels at sites near the middle of the conununity were generally lower than the levels at sites exposed to noise from the major traffic routes.

Traffic is not the only source of noise in the community, however. Particularly high noise levels were observed in the period f~om1500 to 1900 hours on 23 September (at Site 3) and from 1900 to 2300 hours on 26 September (at Site 5). These have been attributed to the low altitude flypast of aircraft going to ox from the nearby airport. Similar results might be obtained if a neighbour" lawn was cut using a power mower. Table LII contains calculated values of Ld, b, and Ld, fo~Sites 3 and 5, both with these unusually noisy periods included in the averaging and with those periods excluded. The latter values are more suitable for estimating the noise reaching these sites from traffic on the nearby roads.

The normalized Ld, values in Table 111 wese obtained using appropriate corrections from Table I. Because traffic noise contains no pure tones and is present throughout the year, and because it is usually considered that some effort is made to control the noise, corrections of 0 dB were used except in the category for type of community. Although Sites 3, 4 and 5 would qualify as "urban residential," the other three sites are clearly "adjacent to heavily travelled roads and industrial aseas.lt Therefore 5 dB was subtracted from the measured Ldn levels at Sites 1, 2 and 6 to obtain the normalized Ld,. With ~hesecorrections, only Site 6 has noise levels outside the range for which the expected community attitude is "no reaction although noise is generally noticeable.'' Although the noise Eevels at Sites 1, 2 and 5 are slightly above the limits recommended by the Ontario Ministry of the Environment, they are sufficiently clo~e to those Eevels that one would predict only marginal interfcrencc with such activities as sleep and speech communication.

Note that although Site G would not be suitable for normal i-esidential development, it is an acceptable site for a motel where outdoor recrearion space is of little importance and adequate sound irlsulation can be provided to ensure negligible sleep disturbance.

4. ANTICIPATED CHANGES IN THE NOISE ENVIRONMENT

As part of the development of the South Ottawa Eastern Community, it is proposed that Johnston Road and should be extended eastwards to Conroy Road and Hawthorne Road. These changes in the road system wmld result in substantially increased traffic en Johnston Road and Hunt Club Road. The primary purpose of this section of this report is to estimate the resulting changes in the noise climate in South Keys and to relate the anticipated noise levels to the social response criteria presented in Section 2.

4.2 Prediction of Road Traffic Noise

Various research groups have developed formulae for calcu- lating the equivalent sound levels produced by road traffic. Although the various models differ in some details, they all give fairly similar results and are typically accurate to within 2 dB. The calculations presented here use the prediction method developed by the Ontario Ministry of Transportation and Communications 13). The A-weighted equivalent noise level may be calculated using the following equation:

Leq = 49.5 + 10.2 loglD (V, + 6Vt) - 13.9 loglO(D) + 0.21 S where : = the A-weighted equivalent sound level (in dB) for a =es one-hour period

V, = number of cars per hour (Gross Vehicle Weight under 10,000 Ib) Vt = number of trucks per hour [Gross Vehicle Weight over 10,000 lb)

D = distance to the edge of the pavement (in ft] S = average traffic speed (in mph).

This equation predicts the noise level in the absence of any buildings, or other surfaces, from which sounct might be reflected. Far comparison with the results reported in Section 3, an additional correction must be made for reflections from the houses.

4.3 Predicted Noise Levels at Site 5

At Site 5 [on Southgate Road at the southern extremity of South Keys), the traffic on the proposed extension of Hunt Club Road is the potential noise scurce of interest. The worst-case peak-hour rraffic volumc anticipated on this road c4) is 2450 vehiclesJhour with 7 per cent heavy vehicles. The estimated hourly average for a 12-hour day (presumably 0700 to 1900 hr) is obtained by multiplying the peak-hour value by 10/12. Thus for the daytime period on this road the following values are appropriate:

Several possible alignments of Hunt Club Road have been discussed. The distance (D) from the edge of the pavement to the homes on Southgate Road obviously depends on the alignment selected, but should not in any case be less than 200 ft. Using D = 200 ft and the values for Vc, Vt and 5 indicated above, the equation gives an average noise level for the daytime period of 58.9 dB. For purposes of comparison with the existing situation [as shown by the results reported in Section 32, it is necessary to add 3 dB to this value to allaw for the noise reflected f~omthe houses. llus the average noise level in the front yard during the daytime period is predicted to be 62 dB. The average noise levels in the evening period [1900 to 2300 hr] would typically be lower than the average daytime level by approximately 5 dB and the nighttime noise levels (2300 hr to 0700 hr) would be approximately 8 dB lower than the daytime levels. These differences are admittedly approximate, but are consistent both with "typical" noise survey results and with the iesults given in Section 3 for the sites exposed to the noise from nearby heavlly-used roads.

Using these values, the Day-Night Average Sound Level (Ld,l was calculated to be: This noise level exceeds the limits recommended by rhe U.S. Environmental Protection Agency and the Onta~ioBIinistry of the Environment by 7 dB and 5 dB, respectively. In addition, it is 5 dB higher than the noise levels attributed To road traffic undcr existing conditions (as presented in Section 33, This difference is marginally noticeable, but it is nevertheless unlikely that the response of residents on Southgate Drive will exceed the "sporadic complaintsT'category of Fi~relb.

4.4 Predicted Noise Levels at Site 1

At Site 2 [and all the other homes an the north side of Eernwood Drive and Viking Drive) the traffic expected on Johnston Road, if it is extended to Conroy Road, is the most serious potential noise source. The estimated worst-case peak-hour traffic volume predicted for this road 141 is 1590 vehicleslhour with 5 per cent heavy vehicles. The approximate average traffic density for a 12-hour daily period may then be calculated to be:

V, = 1260 carsjhour Vt = 65 heavy vehiclesJhour

The proposed speed limit for Johnston Road is S = 30 mph and the distance from the edge of the pavement to the point where the microphone was located at Site 1 is 40 fr allowing for a pavement width of 15 ftllane. Using these values in the equation, and adding 3 dB for the noise reflected from the wall of the house, gives a predicted average noise level at Site 1 of 69-3 dB for the daytime period COT00 to 1900 hour]. As in the analysis for Southgate Road, allowing for reduced noise during the evening and nighttime periods leads to predicted noise levels of 64 dB for the period from 1900 to 23QO hr and 61 dB for the period from 2300 to 0700 hr. Combining these predictions, the Day-Night Average Sound Level (Ldn) was calculated to be:

Lam = 70 dB This substantially exceeds the 57 dB limit recommended by the Ontario Ministry of the Environment and the 55 dB level identified by the U.S. Environmental Protection Agency as "requisite to protect public health and welfare with an adequate rhargin of safety." Although this level should be typical in the part of the yard near the wall of the house, sohewhat higher levels would be expected closer to Johnston Road,

In assessing the impact of this noise, one should recognize that the areas most severely affected are the backyards of the homes, ~lrhichhave been used as outdoor recreation areas for several years. Indoor levels, however, will also he affected, particularly during the summer when it is necessary to open the wind or*.^ for ventilatj on.

AT discussed in Section 3, the Normalized Outdoor Ld, may be obtained by subtracting 5 dB from the measured value of Ld,. As shown by the graph in Cigure lh, typical community response when exposed to such noise would include widespread complaints and possible threats of legal action.

ht the second row of housing from Jolmston Road [on the south side of Fernwood D~iveand Viking Drive] the additional distance from the noise source and the protection provided by the intervening row of houses should he sufficient to reduce the noise to acceptable levels.

The existing noise levels in the South Keys community are typical of a residential urban area. Alrhough the noise levels at homes around the periphery of the community (adjacent to more heavily-used roads) are slightly above the limits proposed by govemmcnt agenctcs such as the Ontario Ministry of the Environment, the existing noise problem does not seem serious.

The proposed extension of FIunt Club Road and Johnston Road will significantly increase traffic passing the southern and northern edges of South Keys. Although the resulting increase in noise levels will be noticeable at homes on Southgate Drive ar the southern edge of the community, it should not seriously interfere with normal activities. The increased noise levels at homes adjacent to Johnston Road, however, will constitute a serious noise problem. ACKNOWLEDGEMENTS

The author wishes to thank the Eastern Community Citizens Planning Committee for their help in arranging for residen~sof South Keys to place the noise monitor on their property and obtain the data printouts, Thanks are also due to Mr. Ken Goselin of the Transportati0~1Department of the Regional Municipality of Ottawa-Carleton for supplying data on the anticipated changes in traffic volume. REFERENCES

1. Infomation on Levels of Environmental Noise Requisite to Protect Public Health and Welfare with an Adequate Margin of Safety. U.S. Environmental Protection Agency Report 550/9-74-004 (March 1974). Available from Superintendent of Documents, U.S. Government hinting Office, Washington, DC 204112.

2. Model Municipal Noise Control By-Law. Onta~ioMinistry of the Environment (May 1976) . Avail able from Ministry of Government Sexvices Publication Centre, Macdonald Block, Toronto, Ontario, M7A 1W8.

3. Hajek, J.J. Ontario Leq Prediction Method: A Brief Outline. Systems Research and Development Branch, Ontario Ministry of Transportation and Communications (June 1976).

4. Predicted traffic volumes. Obtained from Mr. Ken Goselin, Transportation Department, Regional Municipality of Ottawa- Garlet en. TABLE I

Corrections to be added to the outdoor Day-Night Sound Level (Ldn) of intmding noise to obtain the normalized La, (from Ref. 1)

Amount of Correction to be Added Type of to Measured Correction La, in dB

Seasonal Summer (or year-xound operation) Correction Winter only (or windows always closed] Y Correction Quiet suburban or rural community Cremate from large + 10 for QUtdoor cities and from industrial activity and trucking] Noise Level Measured in Normal suburban community [not located near industrial activity) Absence of Intruding Urban residential community [not immediately adjacent to 0 Noise heavily traveled roads and industrial areas) Noisy urban residential community (near relatively busy -5 roads or industrial areas] Very noisy urban residential community -10 Correction No prior experience with the intruding noise +S for Previous Community has had some previous exposure to intruding 0 Exposure noise but little effort is being made to control the noise. Community ' This correction may also be applied in a situation where Attitudes the communj.ty has n'ot been exposed to the naise previously, but the people are aware that bona fide efforts are being made to control the nstse Community has had considerable previous exposure to the intruding noise and the noise maker's relations with the community are good Community aware that operation causing noise is very necessary and it will not continue indefinitely. This correction canbeapplied for anoperatianof limited duration and under emergency circumstances Pure Tane Na pure tone or impulsive character or Impulse Pure tone or impulsive character present Description of microphone location at the measurement site

Site No. Address Details

1 1309 Fernwood Drive 60 ft from centreline of Joflnston Road 2 Corncr of Johnston 40 Et from centreline of Johnston Road Rd. and Albion Rd. 30 Et from centreline of 3 3247 Clearwater Cr. backyard 4 3364 Clearwater CT. front yard 5 3483 Southgate Road South facade; exposed to traffic on and klbion Road 6 2431 Bank Street 40 ft from edge of Bank Street pave- ment, at Southway Motel

Note: In all cases the microphone was located at a distance of approximately 6 ft from the building facade and at a height of approximately 6 Et above the ground. TABLE I14

Summary of average noise lcvcls measured at the monitoring sites

Approximate Daytime Level Nighttime Level Day- Night Approximate (0700-2300 hr) (2300-0700 hr) Level Normalized Site Ld (in dB) La (in dB) Ldn (in dB) Ld, (in dB)

Note 1: The data at Site 6 were obtained for slightly different time intervals than those specified, but this discrepancy should not substanttally alter the results.

Note 2: The second sets of data (in parentheses) for Sites 3 and 5 are the average values excluding the exceptionally noisy intervals attributed to aircraft movements. COMMUHITY AEACl10H VIGOROUS ACTION me,. . e

SEVERbL THREATS OF LEGAL ACT ION OR me* om* .* STROMG APPEALS TO - LOCAL OFFICIbLS TO STOP NOISE

WIDESPREbD COMPLdlNTS OR SINGLE THREAT OF : • *a 3: = 0' LEGAL ACTION

SPmnalc COMPLAINTs

NO REACTlOlJ ALTHOUGH NOISE IS GENERALLY NOTICEABLE

-OUTDOOR DAY/NIGHT SOUND LEVEL OF Ld n INTRUDING NOISE IN dB

COMMUNITY REACTION VIGOROUS ACTION

SEVERALTHREbTS OF LEGAL acrrm OR STRONG APPEbLSTO LOCAL OFFICIALS TO STOP N015E

WIDESPREAD COMPLAINTS OR SIMGLE THREAT OF LEGAL ACTION

SPORADIC COMPLAlMTS t em 1 NO REACTION ALTHOUGH I I

NORMALIZED OUTDOOR DAY NIGHT SOUND LEVEL OF INTRUDING NOPSF IN dB

FIGURE 1

TYPICAL COMMUNITY REACTION TO INTRCIDI FJG NOISE A FUNCTION OF (a) THE OUTDOOR DAY NiGHT LEVEL iLd i AND fb\ THE 4ORMALlZED I1 DAY NISHT LEVEL (FROM REF. 11. FIGURE 2 MAP OF SHE SOUTH KEYS AREA SHOWING NOISE MONITORING FIGURE 30 MEASURED EQUIVALENT 50UNQ PRESSURE LEVELS DURING MONITORING PERIOD AT SITE 1 (1309 FERNWOOD DRIVE).

FIGURE 3t MEASURED EQUIVALENT SOUND PRESSURE LEVEL5 DURING MONllTORING PER100 AT SITE 2 (CORNER OF _IOHNSTON ROAD AND ALBIOW ROAD). 1 FRIDAY 23 CEPT 24 SEPT

FlGURf 3c MEASURED EOUlVALENT SOUND PRESSURE LEVELS DURlNG MONITORING PERIOD AT SITE 3 (3247 CLEARWATER CP,.).

9 SATURDAY 1 OCT 2 OCT 3 DCT

FIGURE 3d MEASURED EQUIVALENT SOUND PRESSURE LEVELS DURING MON1TORING PERIOD AS SITE 4 (3364 CLEARWATER CR.). FIGURE 3e MEASURED EQUIVALENT SOUND PRESSURE LEVELS DURING MONITORING PERIOD AT SLTE5 (3483 SOUTHGATEROAD).

I WEDNESDAY 1 THURSDAY FRIDAY b OCT 7 OCT 8 OCT

FIGURE 31 MEASURED EQUIVALENT SOUND PRESSURE LEVELS OUR ING MONITORING n7n,-- -.-- . .- -- --