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HomeMy WebLinkAboutCT 12-05; La Costa Residential; Tentative Map (CT) (3)NOISE STUDY La Costa Town Square Residential Development Carlsbad, CA RECEIVED FEB 0 6 2013 CITY OF CARLSBAD PLANNING DIVISION Project Proponent: Taylor Morrison 8105 Irvine Center Drive, Suite 1450 Irvine, CA 92618 Prepared by: Jeremy Louden Ldn .GTJIUIIng. /ne.. 446 Crestcourt Lane Fallbrook, CA 92028 760-473-1253 January 17, 2013 Project: 1298-03 La Costa Town Square Noise Report • TABLE OF CONTENTS TABLE OF CONTENTS ••••••••••••••••.••.•••••••••••••••••••••.••••••••••••••••••.••.••.••••••••••••••••••••••••••••••••••••••••••••••••••••.•..••••••••••••••••••• II LIST OF FIGURES ..................................................................................................................................................... II LIST OF TABLES ...................................................................................................................................................... 11 APPENDICES ........................................................................................................................................................... II GLOSSARY OF TERMS ............................................................................................................................................ IJI EXECUTIVE SUMMARY .......................................................................................................................................... IV 1.0 PROJECT INTRODUCTION .............................................................................................................................. 1 1.1 PURPOSEOFTHIS5TUDY ........................................................................................................................................ 1 1.2 PROJECT lOCATION .............................................................................................................................................. 1 1.3 PROJECT SETTING ................................................................................................................................................. 1 2.0 ACOUSTICAL FUNDAMENTALS ...................................................................................................................... 4 3.0 SIGNIFICANCE THRESHOLDS AND STANDARDS .............................................................................................. 5 4.0 NOISE ENVIRONMENT ................................................................................................................................... 6 4.1 EXISTING NOISE ENVIRONMENTONSITE ................................................................................................................... 6 4.2 FUTURE NOISE PREDICTION METHODOLOGY ............................................................................................................. 8 5.0 FINDINGS AND MITIGATION ........................................................................................................................ 10 US! OF FIGURES FIGURE 1-1: PROJECT VICINITY MAP ...................................................................................................................... 2 FIGURE 1-2: PROJECT SITE PLAN ............................................................................................................................. 3 FIGURE 4-1: AMBIENT MONITORING LOCATION .................................................................................................... 7 FIGURE 4-2: MODELED RECEPTOR LOCATIONS ....................................................................................................... 9 FIGURE 5-1: BARRIER LOCATIONS ........................................................................................................................ 10 US! OF TABLES TABLE 4-1: MEASURED AMBIENT NOISE LEVELS ..................................................................................................... 6 TABLE 4-2: FUTURE TRAFFIC PARAMETERS ............................................................................................................ 8 TABLE 5-1: FUTURE EXTERIOR NOISE LEVELS ....................................................................................................... 10 ATTACHMENTS FUTURE NOISE MODEL INPUT AND OUTPUT FILES ............................................................................................... 12 ii Ldn Consulting, Inc. 1/17/13 1298·03 La Costa Town Square Noise Report GLOSSARY OF TERMS Sound Pressure Level (SPL): a ratio of one sound pressure to a reference pressure (Lre1) of 20 ~JPa. Because of the dynamic range of the human ear, the ratio is calculated logarithmically by 20 log (L/lret) A-weighted Sound Pressure Level (dBA): Some frequencies of noise are more noticeable than others. To compensate for this fact, different sound frequencies are weighted more. Minimum Sound Level (Lm;n): Minimum SPL or the lowest SPL measured over the time interval using the A-weighted network and slow time weighting. Maximum Sound Level (L .... ): Maximum SPL or the highest SPL measured over the time interval the A-weighted network and slow time weighting. Equivalent sound level (L.,q): the true equivalent sound level measured over the run time. Leq is the A-weighted steady sound level that contains the same total acoustical energy as the actual fluctuating sound level. Day Night Sound Level (LON): Representing the Day/Night sound level, this measurement is a 24 -hour average sound level where 10 dB is added to all the readings that occur between 10 pm and 7 am. This is primarily used in community noise regulations where there is a 10 dB "Penalty" for night time noise. Typically LON's are measured using A weighting. Community Noise Exposure Level (CNEL): The accumulated exposure to sound measured in a 24-hour sampling interval and artificially boosted during certain hours. For CNEL, samples taken between 7 pm and 10 pm are boosted by 5 dB; samples taken between 10 pm and 7 am are boosted by 10 dB. Octave Band: An octave band is defined as a frequency band whose upper band-edge frequency is twice the lower band frequency. Third-Octave Band: A third-octave band is defined as a frequency band whose upper band- edge frequency is 1.26 times the lower band frequency. Response Time (F,S,I): The response time is a standardized exponential time weighting of the input signal according to fast (F), slow (S) or impulse (I) time response relationships. Time response can be described with a time constant. The time constants for fast, slow and impulse responses are 1.0 seconds, 0.125 seconds and 0.35 milliseconds, respectively. iii Ldn Consulting, Inc. 1/17/13 1298·03 La Costa Town Square Noise Report EXECUTIVE SUMMARY This noise study has been completed to determine the noise impacts associated with the development of the proposed residential project. The project known as La Costa Town Square Residential Development consists of thirty-two (32) new single-family units. The project site is loc:ated north of Rancho Santa Fe Road and between La Costa Avenue and Paseo Lupino in the City of Carlsbad, CA. The results of this analysis indicate that future vehicle noise from Rancho Santa Fe Road is the principal source of community noise that could impact the site. Based upon the findings, the project will require an 8-foot high barrier at the top of slope along Rancho Santa Fe Road for Lots 1-9 and a 6-foot barrier is needed for Lot 28 in order to comply with the City of Carlsbad's Noise Standard of 60 dBA CNEL at the private use areas. The barriers must be constructed of a non-gapping material consisting of masonry, Vz inch thick glass, earthen berm or any combination of these materials. Additionally, a final interior noise assessment is required prior to the issuance of the first building permit. This final report would identify the interior noise requirements based upon architectural and building plans to meet the City's established interior noise limit of 45 dBA CNEL. Based on the exterior modeling the interior noise assessment is needed for Lots 1-10 and Lots 27 & 28 since the second level building facades are above 60 dBA CNEL. It should be noted; interior noise levels of 45 dBA CNEL can easily be obtained with conventional building construction methods and providing a closed window condition requiring a means of mechanical ventilation (e.g. air conditioning) for each building and upgraded windows for all sensitive rooms (e.g. bedrooms and living spaces). iv Ldn Consulting, Inc.1/17/13 1298-03 La Costa Town Square Noise Report 1.0 PROJECT INTRODUCTION 1.1 Purpose of this Study The purpose of this Noise study is to determine potential onsite traffic noise impacts (if any) created from nearby Rancho Santa Fe Road. Should impacts be determined, the intent of this study would be to recommend suitable mitigation measures to bring those impacts to a level that would be considered less then significant. 1. 2 Project Location The proposed project is located within the City of Carlsbad, CA. More specifically, the project is located north of and adjacent to Rancho Santa Fe Road between La Costa Avenue and Paseo Lupino. Access to the project site is from Paseo Lupino via Rancho Santa Fe Road. A general project vicinity map is shown in Figure 1-1 on the following page. 1.3 Project Setting The proposed project consists of 32 single-family residences. The existing site conditions are characterized as disturbed land that was formerly graded but has no structures onsite. Residential uses exist adjacent to the site to the north, east and west. A project site plan is shown in Figure 1-2 on Page 3 of this report. 1 Ldn Consulting, Inc. 1/17/13 1298-03 La Costa Town Square Noise Report " + l r.tc.C .-1 ~ Pal :i'T.Jr - Jltrpor. •pen ~ c " v .... 61\<1 / "" 1:. F s • ~ ~ Ldn Consulting, Inc. 1/17/13 c Figure 1-1: Project Vicinity Map ~~01\1 011-,l\ef(' l:Jo.t• aa ...... p • ''"'~'C'l..1 Lo Costa Oalo:s ~ar:t- r Lll•" Sa" M f"'"' ClU1 f"Y CA.Ib . ~Project Site e:v·'· _r ~tJ Source: Google Maps, 11/12 2 1298-03 La Costa Town Square Noise Report ~ <> N I Source: Latitude 33, 10/12 Ldn Consulting, Inc. 1/17/13 Figure 1-2: Project Site Plan \ l 3 1298-03 La Costa Town Square Noise Report 2.0 ACOUSTICAL FUNDAMENTALS Noise is defined as unwanted or annoying sound which interferes with or disrupts normal activities. Exposure to high noise levels has been demonstrated to cause hearing loss. The individual human response to environmental noise is based on the sensitivity of that individual, the type of noise that occurs and when the noise occurs. Sound is measured on a logarithmic scale consisting of sound pressure levels known as a decibel (dB). The sounds heard by humans typically do not consist of a single frequency but of a broadband of frequencies having different sound pressure levels. The method for evaluating all the frequencies of the sound is to apply an A-weighting to reflect how the human ear responds to the different sound levels at different frequencies. The A-weighted sound level adequately describes the instantaneous noise whereas the equivalent sound level depicted as Leq represents a steady sound level containing the same total acoustical energy as the actual fluctuating sound level over a given time interval. The Community Noise Equivalent Level (CNEL) is the 24 hour A-weighted average for sound, with corrections for evening and nighttime hours. The corrections require an addition of 5 decibels to sound levels in the evening hours between 7 p.m. and 10 p.m. and an addition of 10 decibels to sound levels at nighttime hours between 10 p.m. and 7 a.m. These additions are made to account for the increased sensitivity during the evening and nighttime hours when sound appears louder. A vehicles noise level is from a combination of the noise produced by the engine, exhaust and tires. The cumulative traffic noise levels along a roadway segment are based on three primary factors: the amount of traffic, travel speed, and the vehicle mix ratio or number of medium and heavy trucks. The intensity of traffic noise is increased by higher traffic volumes, greater speeds and increased number of trucks. Because mobile/traffic noise levels are calculated on a logarithmic scale, a doubling of the traffic noise or acoustical energy results in a noise level increase of 3 dBA. Therefore the doubling of the traffic volume, without changing the vehicle speeds or mix ratio, results in a noise increase of 3 dBA. Mobile noise levels radiant in an almost oblique fashion from the source and drop off at a rate of 3 dBA for each doubling of distance under hard site conditions and at a rate of 4.5 dBA for soft site conditions. Hard site conditions consist of concrete, asphalt and hard pack dirt while soft site conditions exist in areas having grade changes, landscaped areas and vegetation. On the other hand, fixed sources radiate outward uniformly as it travels away from the source. Their sound levels attenuate or drop off at a rate of 6 dBA for each doubling of distance. The most effective noise reduction methods consist of controlling the noise at the source, blocking the noise transmission with barriers or relocating the receiver. Any or all of these methods may be required to reduce noise levels to an acceptable level. 4 Ldn Consulting, Inc. 1/17/13 1298-03 La Ccsta Town Square Noise Report 3.0 SIGNIFICANCE THRESHOLDS AND STANDARDS The City of Carlsbad's Noise Guidelines Manual (1995) requires that all exterior sensitive areas shall limit noise exposure. For noise sensitive residential land uses, the City has adopted a policy which has established a "normally acceptable" exterior noise level goal of 60 dBA CNEL for the outdoor areas and an interior noise level of less than 45 dBA CNEL. For residential properties identified as requiring a noise study, the study shall document the projected maximum exterior noise level and mitigate the projected exterior noise level to a maximum allowable noise level as identified in the Noise Guideline Manual. If the acoustical study shows that exterior noise levels cannot be mitigated to the level allowable as identified in this policy or less, the development should not be approved without one or more of the following findings: (1) Changes or alterations have been required in, or incorporated into, the project which avoid or substantially lessen the significant environmental effect (noise). (2) Changes or alterations to avoid or substantially lessen the significant environmental effect (noise) are within the responsibility and jurisdiction of another public agency and not the City of Carlsbad. Such changes have been adopted by such other agency or can and should be adopted by such other agency. (3) Specific economic, social, or other considerations make infeasible the mitigation measures or project alternatives to avoid or substantially lessen the significant environmental effect (noise). If a project is approved with exterior noise levels exceeding the level allowable pursuant to this policy, all purchasers of the impacted property shall be notified in writing prior to purchase, and by deed disclosure in writing, that the property they are purchasing is, or will be, noise impacted and does not meet Carlsbad noise standards for residential property. California Noise Insulation Standards (California Code of Regulations, Title 24) and the City of Carlsbad Noise Element establish an interior noise standard of 45 dBA for residential structures. Acoustical studies must be prepared for residential structures that are proposed to be located within the Community Noise Equivalent Level (CNEL) noise contours of 60 dBA or greater. In addition, the City requires residential structures located within the CNEL noise contours of 60 or greater to prepare an acoustical study. The studies must demonstrate that the building is designed to reduce interior noise to 45 dBA or lower (CNEL). 5 Ldn Consulting, Inc. 1/17/13 1298-03 La Costa Town Square Noise Report 4.0 NOISE ENVIRONMENT 4.1 Existing Noise Environment Onsite Noise measurements were taken using a Larson-Davis Model LxT Type 1 precision sound level meter, programmed, in "slow" mode, to record noise levels in "A" weighted form. The sound level meter and microphone were mounted on a tripod, five feet above the ground and equipped with a windscreen during all measurements. The sound level meter was calibrated before and after the monitoring using a Larson-Davis calibrator, Model CAL 200. The ambient measurements were conducted on October 3, 2012 between 1 p.m. and 1:30 p.m. The results of the noise level measurements are presented in Table 4-1. The measurement was located adjacent to Rancho Santa Fe Road. The overall sound level was found to be 60.3 dBA. The statistical indicators Lmax, Lmin, LlO, LSO and L90, are given for the monitoring location. As can be seen from the L90 data, 90% of the time the noise level is roughly 49 dBA. The noise monitoring location can be seen in Figure 4-1 on the following page. Table 4-1: Measured Ambient Noise Levels ML1 Adjacent to Rancho Santa Fe Road Source: Ldn Consulting, Inc. 10/03/12 Ldn Consulting, Inc.1/17/13 1:00 p.m.- 1:30 p.m. 6 60.3 69.3 42.5 64.0 58.7 48.9 1298-03 La Costa Town Square Noise Report Figure 4-1: Ambient Monitoring Location 7 Ldn Consulting, Inc. 1/17/13 1298-03 La Costa Town Square Noise Report 4.2 Future Noise Prediction Methodology To determine the future noise environment and impact potentials the Caltrans Sound32 noise model was utilized. The critical model input parameters, which determine the projected vehicular traffic noise levels, include vehicle travel speeds, the percentages of automobiles, medium trucks and heavy trucks in the roadway volume, the site conditions (hard or soft) and the peak hour traffic volume. The peak hour traffic volumes range between 6-12% of the average daily traffic (ADT) and 10% is generally acceptable for noise modeling purposes. The required coordinate information necessary for the Sound32 traffic noise prediction model input was taken from the preliminary site plans provided by Latitude 33, October 2012. To determine the future noise levels the preliminary site plans were used to identify the pad elevations, the roadway elevations, and the relationship between the noise source(s) and the receptor areas. Traffic was consolidated into a single lane for each roadway and the roadway segments were extended a minimum of 300 feet beyond the observer locations. To evaluate the future potential noise impacts on the proposed development, outdoor observers were located in the private areas adjacent to the roadways. The first floor modeled observers were placed five feet above the finished pad elevation. In addition, the top of pads were modeled to adjust for grade separation and the natural shielding from the roadways. Table 4-2 presents the roadway parameters used in the analysis including the average daily traffic volumes, vehicle speeds and the hourly traffic flow distribution (vehicle mix) for the future Buildout conditions. The vehicle mix provides the hourly distribution percentages of automobile, medium trucks and heavy trucks for input into the Sound32 Model. The Buildout conditions include the future year traffic volume forecasts provided in the La Costa Square Center EIR Traffic Assessment, 2009 and the peak hour traffic volumes and speeds as shown in Table 4-2. To assess the peak hour traffic noise conditions, 10% of the ADT was utilized. The future traffic noise model also utilizes the common vehicle mix found on City's roadways. The modeled observer locations for a sampling of the Lots of the proposed project are presented in Figure 4-2 below. Table 4-2: Future Traffic Parameters 3 Trucks observed at slower speeds I Vehicle Mixed observed in Carlsbad 8 Ldn Consulting, Inc.1/17/13 1298-03 La Costa Town Square Noise Report Figure 4-2: Modeled Receptor Locations \ \r Modeled Receptors 9 Ldn Consulting, Inc.1/17/13 1298-03 La Ccsta Town Square Noise Report 5.0 FINDINGS AND MmGATION The Buildout analysis was modeled utilizing the roadway parameters described above in Section 4 and shown in Table 4-2 for the future conditions. The modeling results are quantitatively shown in Table 5-1 below. In order to meet the 60 dBA standard, the project will require an 8- foot high barrier at the top of slope along Rancho Santa Fe Road for Lots 1-9 and a 6-foot barrier is needed for Lot 28. Figure 5-1 on the following page shows the location of the required barriers to bring future noise levels to the City of Carlsbad 60 dBA CNEL exterior noise level standards for the proposed outdoor areas. The barriers must be constructed of a non-gapping material consisting of masonry, V2 inch thick glass, earthen berm or any combination of these materials. The S32 models input parameters and output files for the future conditions with and without mitigation are also provided in Attachment A. Table 5-1: Future Exterior Noise Levels Receptor ! Unmitigated Mitigated Noise Second Floor Receptor Location I Noise level Barrier He1ghts Level Noise Level Number (Lot#) (dBA CNEL) (Feet) (dBA CNEL) (dBA CNEL) ' 1 22 57 --57 57 2 25 59 --59 59 3 28 62 6 57 62* 4 1 71 8 60 72* 5 5 71 8 59 72* 6 8 71 8 59 71* 7 9 68 8 60 70* 8 11 60 --59 60 9 14 57 --57 57 10 20 55 --55 55 11 29 55 --55 56 12 32 56 --54 56 * Interior Noise Assessment required if fac;ade noise level is above 60 dBA CNEL. Additionally, an interior noise assessment is required prior to the issuance of the first building permit. This final report would identify the interior noise requirements based upon architectural and building plans to meet the City's established interior noise limit of 45 dBA CNEL. Based on findings the interior noise assessment is needed for Lots 1-10 and Lots 27 & 28 since the second level building facades are above 60 dBA CNEL. It should be noted; interior noise levels of 45 dBA CNEL can easily be obtained with conventional building construction methods and providing a closed window condition requiring a means of mechanical ventilation (e.g. air conditioning) for each building and upgraded windows for all sensitive rooms (e.g. bedrooms and living spaces). 10 Ldn Consulting, Inc.1/17/13 1298-03 La Costa Town Square Noise Report ";\ I / """' / " I Ldn Consulting, Inc. 1{17{13 Figure 5-1: Barrier Locations 11 1298-03 La Costa Town Square Noise Report ATTACHMENT A FUTURE NOISE MODEL INPUT AND OUTPUT FILES La Costa First Floor Unmitigated T-Rancho Santa Fe Road, 1 6034 1 55 1 112 I 50 1 17 1 50 L-Rancho Santa l=e Road, 1 N,2198.1101513821 N1I936.,9st,3n1 N11642.,9091363, N11411.1878,3591 N,985.173513501 N1707.156613401 8-BARRIER 11 1 I 1 I 0 10 1851.,1118,381,381, 1848.1103213811381, 1745.,1017,381,381, 1651.,1006,379,379, 1441.,979,375,375, 1312.,963,371,371, 1217.,945,371,371, 1200.,968,371,371, 8-BARRIER 21 2 I 1 I 0 10 1800.,1187,381,381, 1837.,1201,381,381, 1817.,1308,382,382, Rl 1 I 671500 1772,1529,389.,22 R1 2, 67 1500 1797,1369,388.,25 Rl 3 I 671500 1826,1225,386.,29 Rl 4 I 671500 181311035,386.11 R, 5, 67,500 1627,1012,383.,5 R, 6 I 671500 1465,991,380.,8 R, 7' 67,500 1220,961,376.,9 R,B, 67,500 1303,1077,378.,11 R, 9 I 67,500 1397,1200,379.,14 R, 10 I 67 ,500 1585,1421,385.,20 R1 11, 67 ,500 1691,1289,384.,29 R1 12 , 67 ,500 1580,1159,381.,32 K,-3 ALL,All c,c SOUND32-RELEASE 07/30/91 mLE: La Costa First F=loor Unmitigated REC REC !D DNL PEOPLE LEQ(CAL) 1 22 67. 500. 57.3 2 25 67. 500. 58.7 3 29 67. 500. 62.2 4 1 67. 500. 71.4 5 5 67. 500. 71.1 6 8 67. 500. 71.0 7 9 67. 500. 68.1 8 11 67. 500. 60.0 9 14 67. 500. 57.3 10 20 67, 500. 54.6 11 29 67, 500. 54.8 12 32 67, 500. 55.6 La Costa Mitigated First Aoor T -Rancho Santa Fe Road, 1 6034 1 55 1 112 1 50 1 17 1 50 L-Rancho Santa Fe Road, 1 N,2198.,1015,382, N,1936.,951,372, N,1642.,909,363, N,1411.,878,359, N,985.,735,350, N,707.,566,340, B-BARRIER 1, 1 I 2 , 0 ,0 1851.,1118,381,389, 1848.,1032,381,389, 1745.,1017,381,389, 1651.,1006,379,387, 1441.,979,375,383, 1312.,963,371,379, 1217.,945,371,379, 1200.,968,371,379, B-BARRIER 2, 2 , 2 , 0 ,0 1800.,1187,381,387, 1837.,1201,381,387, 1817.,1308,382,388, R, 1,67,500 1772,1529,389.,22 R, 2, 67,500 1797,1369,388.,25 R, 31 67,500 1826,1225,386.,29 R, 4, 67,500 1813,1035,386.,1 R, 5 I 67,500 1627,1012,383.,5 R, 6, 67,500 1465,991,380.,8 R, 7,67,500 1220,961,376.,9 R, 8, 67,500 1303,1077,378.,11 R, 9, 67,500 1397,1200,379.,14 R, 10 , 67 ,500 1585,1421,385.,20 R, 11 ' 67 ,500 1691,1289,384.,29 R, 12 , 67 ,500 1580,1159,381.,32 K,-3 ALL,ALL c,c SOUND32-RELEASE 07/30/91 TITLE: La Costa Mitigated First Floor REC REC ID DNL PEOPLE LEQ(CAL) 1 22 67. 500. 57.2 2 25 67. 500. 58.6 3 29 67. 500. 56.7 4 1 67. 500. 60.1 s 5 67. 500. 59.1 6 8 67. 500. 59.1 7 9 67. 500. 59.5 8 11 67. 500. 58.7 9 14 67. 500. 56.7 10 20 67. 500. 54.6 11 29 67. 500. 54.5 12 32 67. 500. 53.8 La Costa second Floor T -Rancho Santa Fe Road, 1 6034 1 55 1 112 1 50 t 17 1 50 L-Randlo Santa Fe Road, I N,2198.,1015,382, N,1936.,951,372, N,1642.,909,363, N,l411.,878,359, N,985.,735,350, N,707.,566,340, B-BARRIER 1, 1 I 2 I 0 ,0 1851.,1118,381,389, 1848.,1032,381,389, 1745.,1017,381,389, 1651.,1006,379,387, 1441.,979,375,383, 1312.,963,371,379, 1217.,945,371,379, 1200.,968,371,379, 8-BARRIER 2, 2 , 2 , 0 ,0 1800.,1187,381,387, 1837.,1201,381,387, 1817.,1308,382,388, R, I, 67,500 1772,1529,399.,22 R, 2 I 67,500 1797,1369,398.,25 R, 3,67,500 1825,1225,396.,29 R, 4, 67,500 1813,1035,396.,1 R, 5' 67,500 1627,1012,393.,5 R, 6, 67,500 1465,991,390.,8 R, 7,67,500 1220,961,386.,9 R, 8 I 67,500 1303,1077,388.,11 R, 9' 67,500 1397,1200,389.,14 R, 10 I 67 ,500 1585,1421,395.,20 R, 11 ' 67 ,500 1691,1289,394.,29 R, 12 ' 67 ,500 1580,1159,391.,32 K,-3 ALL,ALL c,c SOUND32-RELEASE 07/30/91 mLE: La Costa Second A()Q( REC REC ID DNL PEOPLE LEQ(CAL) I 22 67. 500. 57.3 2 25 67. 500. 59.2 3 29 67. 500. 62.3 4 1 67. 500, 71.6 5 5 67. 500, 71.5 6 8 67. 500. 71.4 7 9 67. 500, 70.1 8 11 67. 500. 60.4 9 14 67. 500. 57.3 10 20 67. 500. 55.0 11 29 67. 500. 55.7 12 32 67. 500. 56.2