17 9761nt01b (carnlough road inward noise impact …€¦ · four stories in height with the...

1.0 INTRODUCTION

Crekav Trading GP Limited are seeking permission for a revised site layout at the Carnlough Road site, Cabra, Dublin 7. The development will consist of the construction of 420 no. residential units (419 no. apartments and 1 no. house) comprising 93 no. 1 bed, 260 no. 2 bed and 66 no. 3 bed units and neighbourhood centre comprising of 4 no. retail units (2,895.5 sq.m.) including convenience supermarket with ancillary off licence, office (101.6sq.m.), community centre (441.8 sq.m.), creche (328.3 sq.m.) and 402 no. car parking spaces (374 no at basement levels (298 no. to serve the residential units and 76 no. to serve the retail units) and 28 no. at surface level (20 no. to serve the residential units and 8 no. to serve the retail units) and 484 no. bicycle parking spaces (368 no. at basement level and 116 no. at surface level) on a site of 3.86 hectares.

An inward noise impact assessment was submitted as part of planning application for 321 residential units at the site (DCC Ref: 2387/16). The permitted scheme included for a total of 8 buildings up to 4 stories in height. The noise impact report which accompanied the planning application (JH/15/8337NR01d which is included in Appendix A for reference), included recommended sound insulation values for glazing and ventilation to residential buildings in order to achieve acceptable internal noise levels. This technical note summarises the inward noise impact of the revised proposal at the higher elevations of Blocks A, D and F. The report also includes discussion on the current and future baseline noise and vibration environment following updated site surveys to include the operational Phoenix Park Rail Line.

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TECHNICAL NOTE ____________________________________

Project Cabra SHD

Subject Inward Noise Impact relating to updated site layout

Author Jennifer Harmon

Date 12 December 2017

Ref. 17/9761NT01b

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JH/17/9761NT01b AWN Consulting Limited __________________________________________________________________________________________

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2.0 SITE DESCRIPTION

The subject site is bounded to the east by a railway line which connects Connolly and Heuston Stations, via the Phoenix Park Tunnel. The site is accessed from the R147 Road (Navan Road) to the south of the site. Residential dwellings along Carnlough Road and Fassaugh Avenue form the western and northern site boundaries. Figure 1 illustrates the proposed site layout.

Figure 1 Site context The development will be developed across 9 blocks (A to I). The proposed neighbourhood centre within Blocks H and I are a mixture of single and two storey buildings. Block A is a mixture of retail and residential units, the majority of which are four stories in height with the north-east residential block extending to eight stories. Blocks B, C, E and G are residential apartment blocks and extend to four stories in height. The remaining blocks D and F both extend to eight stories in height.

Figure 2 Site layout The layout of the proposed development is such that the rail line slopes down within a cutting to a level some 3 to 4m below the level of the proposed site buildings. This coupled with the proposed 2.4m high boundary wall along the length of the development and the rail line provides a level of screening to lower floors of the apartment buildings and amenity areas. The closest apartment building is some 30m from the operational Phoenix Park rail line.

Phoenix Park Line

N

A

B

C

D

E

F

G

H I


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3.0 NOISE ENVIRONMENT

The site is relatively well shielded from surrounding noise sources. Road traffic was noted to be the main background noise source across the site. Two sections of rail line form the eastern boundary. The closest (western) line is a decommissioned shunting area and is no longer in use. The most eastern line is used intermittently for movement of freight trains and shunting trains between Inchicore and Connolly for maintenance works. This line was upgraded in 2016 for passenger trains connecting Connolly Station and the Southern Cork Line. Currently, this service operates between peak am and pm periods with a small number of movements between peak hours. It is proposed that up to 4 trains per hour in each direction will be in use during peak hours with a less frequent service in between, operating for an expected duration of 18hrs per day. Freight services will continue as at present with approximately two container trains a day in each direction and empty train transfers from Connolly to Heuston and Inchicore for maintenance.

3.1 Noise and Vibration Surveys

An updated noise survey was undertaken at the development site in order to capture the most up to date noise environment and also to capture the operation of passenger rail movements using the Phoenix Park Rail line. Survey details are summarised in the following sections. A vibration survey was also conducted at the site.

3.1.1 Survey Location

The monitoring location was positioned along the south-eastern site boundary, along the line of the proposed apartment buildings at a distance of approximately 5m from the railway boundary fence (approximately 30m from the Phoenix Park rail line). The microphone was positioned at a height of 3.8m above ground level. Figures 3 and 4 illustrate the position of the monitoring equipment.


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Figure 3 Noise and Vibration Monitoring Locations

Noise Monitor Install (N1) Vibration Monitor Install (V1) Figure 4 Noise and Vibration Monitoring Installations 3.1.2 Survey Periods

An unattended noise and vibration survey was conducted at the monitoring location determine the existing levels of noise at the closest façade of the proposed dwellings to the rail line over day and night-time periods. The survey was conducted between 17:28hrs on 6 September to 10:30hrs on 9 September 2017. The equipment was set to log over 5 minute periods.

N1

V1


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Site clearance works (including earth moving equipment and some demolition works) were taking place at the site during daytime periods, approximately 20 to 60m from the monitoring position. The works occurred typically between the hours of 07:30 and 17:00hrs, therefore measured noise levels outside of these hours have been reviewed. The equipment was set to log over 1 minute periods.

3.1.2 Survey Equipment

The noise survey was undertaken using a Rion NL-52 noise meter with environmental kit. The vibration survey was undertaken using a Instantel Minimate tri axial vibration meter.

3.1.3 Survey Parameters

The following parameters were recorded during the survey:

LAeq,T This is the equivalent continuous sound level. It is a type of average and is used to describe a fluctuating noise in terms of a single noise level over the sample period (T).

LAF90 Refers to those A-weighted noise levels in the lower 90 percentile of the

sampling interval; it is the level which is exceeded for 90% of the measurement period. It will therefore exclude the intermittent features of traffic and is used to describe a background level. Measured using the “Fast” time weighting.

LAFmax The maximum RMS A-weighted sound pressure level occurring within a

specified time period. Measured using the “Fast” time weighting.

PPV Peak Particle Velocity is the defined as the instantaneous maximum velocity reached by a vibrating element as it oscillates about its rest position. It is measured in millimetres per second.

3.1.4 Survey Results - Noise

The results of the noise survey are presented in Figure 5 overleaf.


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Figure 5 Graphed Noise Levels at Carnlough Road for Full Survey Period

The relevant periods when on-site construction works were taking place are clearly evident in the graphed noise data as confirmed from audio recordings. During periods when construction works had ceased, the main sources of noise were from distant road traffic, bird song, overhead aircraft and intermittent passing trains at low level.

During the site set up and collection, passenger trains were observed along the eastern rail line when passing the site. The train speed was noted to be slow whilst passing the site and the contribution from a passing train was just audible above the ambient noise environment.

Table 1 overleaf presents a summary of the measured noise levels during daytime hours when construction works were not taking place (typically 17:00 to 23:00hrs) and during the night-time period (07:00 to 23:00hrs) for the monitored periods.


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Period / Scenario Measured Noise Levels, dB

LAeq LA90 LAfmax

6 Sept 17: Daytime No Construction (17:00 – 23:00hrs)

Lowest 41 37 47

Highest 55 44 74

Average 47 41 57

6 /7 Sept 17: Night-time (23:00 – 07:00hrs)

Lowest 35 32 44

Highest 55 46 71

Average 44 37 51

7 Sept 17: Daytime No Construction (17:00 to 23:00hrs)

Lowest 44 41 49

Highest 52 46 68

Average 48 44 58

7/8 Sept 17: Night-time (23:00 – 07:00hrs)

Lowest 40 36 48

Highest 54 44 66

Average 44 39 52

Table 1 Noise Monitoring Results Summary

Average ambient noise levels over daytime periods in the absence of construction activity were measured in the range of 47 – 48dB LAeq. This included the evening period when the Phoenix Park Rail line was operating its evening service. During the night-time period, average ambient noise levels measured 44dB LAeq. Noise levels have been reviewed separately for the peak ‘night-time’ hour i.e. between 06:00 and 07:00hrs when passenger trains potentially may operate along the Phoenix Park Rail Line. Additional analysis has also been undertaken for the evening peak period, between 17:30 and 18:30hrs and 18:30 and 19:30hrs when train numbers are at their highest along this line. Due to construction works occurring during the morning period, it was not possible to establish normal am peak noise levels (08:00 to 09:00hrs).

Table 2 summarise the noise levels recoded over each peak hourly period.

Period Time Measured Noise Levels, dB

LAeq LA90 LAfmax Note 1

Daytime pm peaks

17:30 - 18:30 48 43 59 (74)

18:30 - 19:30 48 42 60 (68)

Night-time peak 0600 - 07:00 50 44 60 (71)

Daytime pm peaks

17:30 - 18:30 49 45 59 (66)

18:30 - 19:30 49 45 61 (67)

Night-time peak 0600 - 07:00 49 43 59 (66)

Table 2 Noise Monitoring Results During Peak daytime and night-time periods

Note 1 LAFmax values are presented as average values over the hourly period. The highest LAFmax value is included in parenthesis.


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Noise levels during the 6 peak hours assessed measured broadly similar results, measuring between 48 and 50dB LAeq with maximum noise levels measured between 66 and 74dB, averaging between 59 and 61dB LAFmax.

The background noise level during these periods also measured similar noise levels between 42 and 45dB LA90. The results of the analysis indicate that at the closest boundary of proposed residential buildings, noise levels are in the range of 48 to 50dBLAeq,1hr, during the peak hours of passing rail along the Phoenix Park rail line. This measured value takes into account all surrounding sources including rail, road traffic and bird song.

3.1.5 Survey Results – Vibration

Peak Particle Velocity (PPV) was recorded at monitoring location V1 over the 2 day period. Table 3 summarises the maximum PPV values recorded during the daytime period (excluding periods of construction) and over the full night-time period.

Date / Period Maximum PPV (mm/s)

Vertical Horizontal

6 Sept 17 - Daytime 0.11 0.10 0.10

6 Sept 17 - Night-time 0.08 0.08 0.08

7 Sept 17 - Daytime 0.11 0.11 0.10

7 Sept 17 - Night-time 0.10 0.08 0.08

8 Sept 17 - Daytime 0.10 0.08 0.08

8 Sept 17 - Night-time 0.11 0.08 0.08

Table 3 Maximum PPV values recorded at V1

The results of the vibration survey indicate that the maximum PPV values recorded over the full monitoring period were in the range of 0.08 to 0.11mm/s. During all other periods PPV values were in typically of the order of 0.06 mm/s.

3.2 Summary of Noise and Vibration Environment

Review of the measured noise and vibration results at the Carnlough Road development site indicates that the noise environment is relatively low during both day and night-time periods. Whilst the Phoenix Park Rail line was in operation during the survey, the contribution of this source to measured noise levels at the monitoring position was low. Observations made on site note that due to the low speed of passenger trains along this line, noise levels associated with a passing train were subjectively low. Similarly, vibration levels recorded at the monitoring position were low and subjectively, vibration was not detectable during a train pass by. Noise measurements were also undertaken at the site during May 2015 in support of the planning application for the approved scheme (DCC Ref: 2387/16). Average ambient noise levels during this survey measured slightly higher daytime noise levels (51dB LAeq,16h) and higher night-time noise levels (47dB LAeq,8hr) compared to the 2017 survey. Whilst the Phoenix Park Rail line was in operation during the most recent survey, it is possible that other rail activities were less frequent (freight trains, shunting trains etc.). In summary, average ambient noise levels at the site are measured in the range of 47 to 51dB LAeq during daytime periods and in the range of 44 to 47dB LAeq during night-time periods.


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4.0 FUTURE NOISE LEVELS 4.1 Future Scenario Assumptions

Future noise levels at the development site have the potential to be increased in the event that the Phoenix Park rail line operates a more frequent service. Whilst specific details of the number and hours of operation are not known at this stage, it is understood that up to 4 trains per hour in each direction will be in use during peak hours with a less frequent service in between, operating for an expected duration of 18hrs per day. Whilst the measured noise levels in Section 3 represent noise levels at the closest apartment buildings to the rail line with the inclusion of the Phoenix Park passenger rail service in its current operation, there is potential for the baseline environment to be increased, should the rail frequency increase. Previous site noise models for the proposed rail line included as part of the sites original planning application calculated noise levels across the development site using a range of rail noise modelling assumptions (Report Ref: JH/15/8337NR01d). The source data assumed for the passing rail included for passing trains at significantly higher speeds than those currently experienced along the section of rail line along the sites eastern boundary. In addition, the number of passing trains over day and night-time periods was highly worst case to account for full future usage of the line. In reality, based on updated noise surveys, noise levels associated with passing trains at the site are lower than those modelled and the number of fleet passing is a portion of those assumed in the noise model. In order to assess the potential worst case future noise levels at the facades of the increased height apartments, the noise model development for the site has been updated to incorporate the new proposed site layout.

In order to calculate a daytime 16-hour value and an 8-hour night-time value, the following train numbers have been assumed over the course of a 24-hour period.

Time Period Modelled Train Numbers

Inbound Outbound Total

Daytime (07:00 – 19:00hrs)

36 36 72

Evening (19:00 – 23:00hrs)

12 12 24

Night-time (23:00 to 07:00hrs)

8 8 16

Table 4 Daily train numbers modelled along adjacent line Source data Source data used for the operational rail is based on measurements of

passing fleet from other operational rail lines with DMU trains. The passing fleet was typically travelling at moderate to high speeds and represent a worst case scenario with higher noise emission levels compared to those observed on the Carnlough Road site.

As part of the development plans, a 2.4m high boundary wall will be constructed along the eastern site boundary parallel to the railway line which has been incorporated into the site noise model. Based on the model inputs discussed above, noise levels at the facades of revised Blocks A, D and F have been predicted for a day and night-time periods are presented overleaf.


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4.2 Calculated Noise Levels at Revised Building Facades 4.2.1 Daytime

Noise levels have been calculated at specific receptor locations representing the most exposed facades at upper floor levels of residential dwellings along the eastern boundaries of Blocks A, D and F. Table 5 presents the calculated daytime noise levels at these locations.

Receiver No.

Description Daytime LAeq 16hr

4th Floor 5th Floor 6th Floor 7th Floor

1 Block F North East 57 57 57 56

2 Block F North East 57 57 57 n/a

3 Block F South East 57 57 57 56

4 Block F South East 57 57 57 n/a

5 Block D North East 57 57 57 56

6 Block D East 58 57 57 n/a

7 Block D South East 58 57 57 57

8 Block A North 54 54 54 54

9 Block A East 57 57 57 57

Table 5 Calculated Daytime Noise Levels at upper levels of Blocks A, D and F Noise levels at the upper floors of Blocks A, D and F are in the range of 56 to 58dB LAeq,16hr assuming the various worst case assumptions included in the noise model.

4.2.2 Night-time Table 6 presents the calculated noise levels at the same 7 assessment locations representing the upper floor levels of Blocks D and F during the night-time period.

Receiver No.

Description Night-time LAeq 8hr

4th Floor 5th Floor 6th Floor 7th Floor

1 Block F North East 52 52 52 51

2 Block F North East 52 52 52 n/a

3 Block F South East 53 53 53 52

4 Block F South East 53 53 53 n/a

5 Block D North East 53 53 53 52

6 Block D East 53 53 53 n/a

7 Block D South East 53 53 53 52

8 Block A North East 49 49 49 49

9 Block A South East 52 52 52 52

Table 6 Calculated night--time Noise Levels at upper levels of Blocks D and F

Noise levels at the upper floors of Blocks A, D and F are in the range of 51 to 53dB LAeq,1hr assuming the various worst case assumptions included in the noise model.


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5.0 ASSESSMENT CRITERIA

There are no Statutory Irish guidelines relating to acceptable noise levels at new properties from environmental sources (rail, road or other). In this instance, best practice dictates that reference is made to National or International guidance. The following assessment documents have been used to determine the range of suitable criteria for the development under assessment.

5.1 Noise 5.1.1 Dublin Agglomeration Environmental Noise Action Plan December 2013 to November

2018

The Noise Action Plan defines the following threshold values for areas with “Desirable Low” and “Undesirable High” sound levels. The following Noise Limit Values are set out in the plan which define these assessment thresholds. Desirable Low Sound Levels < 50 dB(A) Lnight < 55 dB(A) Lday

Undesirable High Sound levels >55 dB(A) Lnight >70 dB(A) Lday Lday is the A-weighted long-term average sound level between 07.00 and 19.00. Lnight is the A-weighted long-term average sound level between 23.00 and 07.00 These threshold values are an assessment tool to be used by the relevant Local Authorities and City Council for the management of noise levels throughout the agglomeration of Dublin. In the absence of other limit values, they are a useful guide for defining the noise character of an area and can be used as a planning tool for new developments. The Action Plan states the following for areas which fall between areas of Desirable Low and Undesirable High Sound levels:

“Management of Areas between the Thresholds Careful consideration of environmental noise pollution when planning for new developments will be a key factor in the management of the noise environment in the interest of sustainable development. Setting out clear planning policy relating to noise, and incorporating environmental mitigation noise strategies into the development, planning and local area planning processes will help to ensure that the existing noise climate is preserved where appropriate. With the twin focus on mitigation of noise for the most exposed residents, and preservation through designated quiet areas of the least exposed areas, there is a risk that the majority of households, which sit between these two categories, are not provided for within the action planning process. It is acknowledged that the action plan needs to provide a means of preventing


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and avoiding detrimental levels of long term noise exposure, and the development of planning guidance plays a key role in support of this target”

5.1.2 British Standard BS 8233 (2014) BS 8233 sets out recommended internal noise levels for dwellings types from external noise sources. The recommended internal noise levels for residential developments are set out below.

Typical situations Design Range, LAeq,T dB

Daytime LAeq,16hr (07:00 to 23:00hrs)

Night-time LAeq, 8hr (23:00 to 07:00hrs)

Livings rooms 35 – 40 n/a

Bedrooms 35 30

Table 7 Summary of Recommended Internal Noise Levels from BS 8233 (2014) Referring to Table 7 above, the following day and night time internal noise criteria are proposed for the development: Daytime (07:00 to 23:00hrs) 35 – 40dB LAeq,16hr Night-time (23:00 to 07:00hrs) 30dB LAeq, 8hr

5.2 Vibration

Peak particle velocity (PPV) is commonly used to assess the structural response of buildings to vibration. Reference to the following documents has been made for the purposes of this assessment in order to discuss appropriate PPV limit values.

British Standard BS7385: 1993: Evaluation and measurement for vibration in

buildings Part 2: Guide to damage levels from ground borne vibration, and; British Standard BS5228-2: 2009 + A1: 2014: Code of practice for noise and

vibration control on construction and open sites – Vibration.

BS5228-2 and BS7385 advise that, for soundly constructed residential property and similar structures that are generally in good repair, a threshold for minor or cosmetic (i.e. non-structural) damage should be taken as a peak component particle velocity (in frequency range of predominant pulse) of 15mm/s at 4Hz increasing to 20mm/s at 15Hz and 50mm/s at 40Hz and above. The standard also notes that below 12.5 mm/s PPV the risk of damage tends to zero. The recommended vibration limits in order to avoid cosmetic damage to buildings, as set out in both documents referred to above, are reproduced in Table 7. The documents note that minor structural damage can occur at vibration magnitudes which are greater than twice those presented in Table 8. Major damage to a building structure is possible at vibration magnitudes greater than four times the values set out in the Table. It should be noted that these values refer to the base of the building.

Vibration (in terms of peak particle velocity) at the closest part of sensitive property to the

source of vibration, at a frequency of 4 to 15Hz 15 to 40Hz 40Hz and above

15mm/s 20mm/s 50mm/s Table 8 Transient vibration guidance values for avoidance of cosmetic building damage


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Human response to vibration stimuli occurs at orders of magnitudes below those associated with any form of building damage, hence vibration levels lower than those indicated in Table 10.2 can lead to concern. BS5228-2 also provides a useful guide relating to the assessment of human response to vibration in terms of PPV. Whilst the guide values are commonly used to compare typical human response to construction works, they tend to relate closely to general levels of vibration perception from other general sources. Table 9 below summarises the range of vibration values and the associated potential effects on humans.

Vibration Level Effects

0.14 mm/s Vibration might be just perceptible in the most sensitive situations

for most vibration frequencies. At lower frequencies people are less sensitive to vibration.

0.3 mm/s Vibration might be just perceptible in residential environments.

1 mm/s It is likely that a vibration level of this magnitude in residential

environments will cause complaint. Table 9 Guidance on effects of human response to PPV magnitudes

The standard notes that single or infrequent occurrences of these levels do not necessarily correspond to the stated effect in every case.

6.0 ASSESSMENT OF RESULTS 6.1 Noise Action Plan

The results of the assessment are compared against the noise threshold values set out in the Dublin Agglomeration Noise Action Plan.

6.1.1 Existing Noise Levels

The existing noise environment at the site is well shielded from road traffic noise and is exposed to intermittent train pass by’s along the rail line. The average daytime noise level at the site taking account of current and previous surveys, 47 to 51dB Lday

is below the Desirably Low daytime threshold value of 55dB Lday set out in the Noise Action Plan. Existing average night-time noise levels of 44dB Lnight at the site are also below the Desirably Low threshold value of 50dB Lnight, taking into account the existing sources contributing to the existing noise environment. Average night-time noise levels of 47dB Lnight previously measured at the site (during surveys undertaken during May 2015) are also below these threshold levels.

6.1.2 Future Noise Levels

Future noise levels at the site, assuming full operation of the Phoenix Park Rail Line and assuming high source emission data for passing trains are compared against the noise action plan threshold values. During daytime periods, predicted rail noise levels along the eastern façade of the upper floors of Blocks A, D and F have a predicted noise level between 56 and 58dB LAeq,16h which is marginally above the desirably low threshold level of 55dB Lday. The calculated noise level at these facades are, however, comfortably below the Undesirable Sound Level of >70dB Lday.


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During night-time periods, the calculated rail noise levels along the eastern façade at the upper floors of Blocks A, D and F have a calculated in the range of 51 to 53dB which are marginally above the desirably low Noise Action Plan threshold value of 50dB Lnight. The calculated night-time noise level at these facades are, however, all below the Undesirably High threshold value of >55dB Lnight. The results of the assessment have concluded that existing noise levels at the site and those calculated under a worst case future scenario are within an acceptable range of noise levels in line with the Dublin Agglomeration Noise Action Plan.

6.2 BS 8233

The external noise levels predicted at the facades of the residential properties during the future rail scenario have been used to calculate noise levels within the living and bedroom spaces of the assessed properties. The calculations take account of the surface area of the building elements (brick work, glazing etc.), their sound reduction indices and the internal room volumes of the spaces under consideration. As is the case in most buildings, the glazed elements of the building envelope are typically the weakest element from a sound insulation perspective. The sound reduction index (SRI) recommended for glazing to the development is included within Table 9 below. For the eastern façade, a higher performance glazing has been specified in order to achieve internal noise levels within living spaces and bedrooms and also to protect against maximum noise levels from individual train pass by’s. For other remaining facades set back from the rail line, a standard thermal double glazed unit is advised with a sound insulation performance equal to or greater to that outlined in Table 9 below. The higher performing glazing of 40dB Rw has been specified in order to ensure that both suitable internal ambient and maximum noise levels are achieved within sensitive spaces, particularly during night-time periods.

Glazing Specification

Octave Band Centre Frequency (Hz) Nominal Overall dB

Rw125 250 500 1k 2k 4k

Eastern Façade – All apartment buildings

26 28 38 47 43 51 40

Remaining facades

24 20 25 35 38 35 31

Table 10 Sound insulation performance requirements for glazing, SRI (dB) Taking account of the predicted external noise levels and the recommend glazing to the building facades, the calculated internal noise levels are summarised in the following Sections.

6.2.1 Daytime (07:00 to 23:00hrs)

Noise levels have been calculated within the living spaces of Blocks A, D and F where external daytime noise levels are calculated between 56 and 58dB LAeq,16hr. Taking account the glazing performance and the various glazing and room dimensions, the internal calculated noise levels are all below 35dB LAeq. The


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calculated internal noise levels achieve the recommended internal noise levels for living and dining areas from BS 8233.

6.2.2 Night-time (23:00 to 07:00hrs) Noise levels have been calculated within the living spaces of Blocks A, D and F with external night-time noise levels in the range of 51 to 53dB LAeq,8hr. Taking account the glazing performance and the various glazing and room dimensions, the internal calculated noise levels are typically below 27dB LAeq. The calculated internal noise levels achieve the recommended internal noise levels for bedrooms from BS 8233. During the peak night-time periods, with external noise levels up to 57dB LAeq,1hr, the calculated internal noise levels are all below 30dB LAeq, 1hr.

6.2.3 Windows Open

The results of the assessment above indicate that with windows closed, the range of internal noise levels at all apartments are all below the recommended criteria from BS 8233 during day and night-time periods. The level of sound attenuation across a partially open window is typically taken to be 15dB(A) in line with WHO and BS 8233 guidance. Assuming this level of performance, internal noise levels within the most exposed facades along the eastern boundary during the future worst case scenario are of the order of 42dB LAeq within living and dining rooms with windows open during daytime periods. In line with BS 8233 guidance which states “Where development is considered necessary or desirable, despite external noise levels above WHO guidelines, the internal target levels may be relaxed by up to 5dB and reasonable internal conditions still achieved” In this instance, worst case internal noise levels of 42dB LAeq,16hr within living spaces is still considered to provide a reasonable internal noise environment. For bedrooms at the most exposed eastern facades, internal noise levels of the order of 38dB LAeq,8hr are calculated with windows open, assuming the worst case assumption of train numbers over the night-time period. In reality, the proposed train service will only operate during the shoulder night-time periods, i.e. potentially between 23:00 and 00:00hrs where a significantly reduced number of trains would pass and during the early morning, between 06:00 and 07:00hrs. For the remainder of the night-time periods, the Phoenix Park Rail line service will not be in operation. It should be noted; the scenarios above relate to assumed future worst case noise levels at the site taking into account a range of worst case assumptions. Referring to the existing noise levels measured at the site, inclusive of the current operation of the rail line, internal noise levels during day and night-time periods would be within acceptable levels assuming open windows for ventilation. Notwithstanding this, consideration should be given to the inclusion of an acoustically attenuated ventilation strategy in order to provide an option for residents to obtain a suitable level of ventilation without the requirement to open windows during night-time periods. Options which should be considered include adjustable hit and miss acoustic ventilators or acoustic trickle vents built into the façade or window frames respectively. For any acoustic ventilators chosen, for eastern facades with a glazing specification of 40dB Rw, any background ventilation system will be required to achieve a minimum D,n,e,w value of 42dB. This can be achieved using an acoustic in


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window or wall vent. For all other facades, any background vent should be chosen to achieve a Dn,e,w value of 32dB.

6.3 Vibration

Measured vibration levels at monitoring location V1, some 30m from the operational railway line, measured maximum PPV value in the range of 0.8 to 0.11mm/s which includes passing passenger and freight trains.

Reference to BS 5228 Part 2: 2008+A1 2014 as reproduced in Table 9, at PPV levels of 0.14mm/s Vibration might be just perceptible in the most sensitive situations for most vibration frequencies and at PPV values of 0.3mm/s Vibration might be just perceptible in residential environments. In this instance, given the low magnitude of vibration recorded at the site, vibration impacts at residential buildings are below the typical threshold of perception for building occupants.

6.4 Irish Rail Activities

Specific comment in relation to potential activity within the Irish Rail lands at the south-east portion of the site, is discussed in detail in the noise report issued in support of the original planning application. Noise impacts at the revised buildings will be of similar magnitude to those assessed previously and hence the impact assessment and recommendations relating to this activity remains unchanged. As noted in the previous assessment, the inclusion of glazing with a high sound insulation performance along the eastern façade of the development buildings (Refer to Table 10) will provide an acceptable internal noise level within bedrooms, assuming windows can be maintained closed during any scheduled works.

6.5 Service Yard Activities

A noise assessment has previously been undertaken to determine the potential likely noise impacts associated with the operation of the service yard (Report Ref JH/15/8337NR02 included in Appendix B) The assessment has concluded that noise levels at the nearest adjacent properties to the service yard are within the recommended daytime noise level at both ground floor and first floor levels under a scenario whereby the service yard is in full operation. The combination of strict periods when deliveries can take place (08:00 to 18:00hrs), the intermittent periods over which deliveries will occur, the boundary wall proposed, and the lower ground level of the service yard is concluded to result in noise levels within the relevant daytime noise limit at the nearest residences.

The use of the service yard will be intermittent and will not be in use for the majority of the daytime period. There are no night-time activities permitted within the service yard, hence no noise impacts are associated with this area during night-time periods (23:00 to 07:00hrs). The assessment has concluded that under the various worst case assumptions set out within this report, the current boundary wall height coupled with the lower ground level of the service yard is sufficient to reduce noise levels at the closest properties to within the recommended daytime noise level.


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7.0 SUMMARY AND CONCLUSION

An inward noise impact assessment has been undertaken at the development site focusing on the most exposed facades of the residential apartment buildings facing the railway line taking account of the higher elevations proposed. Using guidance outlined in the Dublin Agglomeration Noise Action Plan (2013 – 2018), the revised development in question has been assessed in terms of its noise exposure category. Based on this assessment, both existing and future noise levels at the development site has been found to be comfortably below the range of noise levels deemed to be Undesirably High during day and night-time periods and just above the threshold values considered to provide a Desirably Low noise environment at the most exposed upper facades along the eastern boundary The results of the assessment have concluded that during daytime periods, internal noise levels are calculated to be within acceptable levels for living spaces, as defined in BS 8233 with windows closed at all facades taking account of the proposed glazing recommended for the development. During daytime periods, internal noise levels with windows open at the upper floors of the eastern facades are calculated to be just above standard recommended internal noise levels, however, the range of noise levels calculated are still considered reasonable in accordance with BS 8233 (2014). During night-time periods, internal noise levels are calculated to be within acceptable levels for bedrooms, as defined in BS 8233 with windows closed at the most exposed facades along the eastern boundary taking account of the recommend glazing specification. Noise levels with windows open for bedrooms along this façade are above the standard recommended internal noise levels assuming a worst case future operational scenario for the Phoenix Park Rail Line and hence consideration needs to be given to providing a suitable attenuated ventilation strategy to future proof the development. Normal operation of the Phoenix Park Rail Line is not expected between the hours of 00:00 and 06:00hrs, hence during the majority of the night-time period, noise levels will be in line with current ambient noise levels. The assessment has recommended a suitable glazing and attenuated ventilation strategy for the east facing façades of the development at all floors to provide a suitable level of free ventilation without compromising the acoustic performance of the façade.

APPENDIX A


APPENDIX B

17 9761nt01b (carnlough road inward noise impact …€¦ · four stories in height with the...

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