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D1 APPENDIX D ADDITIONAL CONTOUR ANALYSIS FOR HEAVY TRUCKS TABLE OF CONTENTS HEAVY TRUCK NOISE CONTOUR DISCUSSION ...........................................................D2 Northern California Test Sites .........................................................................................D2
D2 HEAVY TRUCK NOISE CONTOUR DISCUSSION Northern California Test Sites Lakeville Test Site. The typical vertical distributions at the Lakeville site reduce from the maximum profile level by 10 dBA at heights ranging from 5.3 to 8ft (1.6 to 2.4m), and the profiles flatten out at or below 9.8ft (3m). In some cases, the profiles start to reduce like the typical truck runs and show a jump in height at a particular noise level. Run 2, which was identified in Figure 32 of the main report, âbumps-upâ at 88 dBA, which may be indicative of a small contribution of exhaust outlet noise. Contours for this case are shown in Figure D1. Notice that the overall A-weighted noise levels for the rear tires in this case reach 79 dBA, matching those levels of the drive axle tires. This pattern also appears in the contours for the typical truck in Figure 25 of the main report and for many of the heavy-duty vehicles, in general, at all sites. At 4,000 Hz in Figure D1, there is also an indication of noise from the outlet of the exhaust stack about 11ft (3.4m) above the pavement. This source only appears in the higher frequency bands and has a level much lower (26 dB) than the overall level. It is possible at these frequencies that the noise is aerodynamic and produced by âjettingâ of the exhaust gases through the restriction of the outlet.
Fi Some sp Run 10, f indicates noise sou 9.8ft (2 t trucks of expanded band. In contribut axle tires somewha gure D1: Ov ecial-case ru or instance, the presenc rce levels. T o 3m) above Figures 25 vertically particular, th ing more no as they are t different d erall, 800, a ns with ele yields level e of a diffe his noise so the ground of the main around the e contours t ise for this for the tru istribution o nd 4,000 H vated noise s about 84 d rent noise s urce distrib . Contours f report and D tractor for b end to bulg truck. Also, cks of Figu f noise sour D3 z contours o sources we BA at a hei ource distri ution would or Run 10 a 1 above, th oth the ove e in the area the contour re 25 of the ces. For the f truck pass re identifie ght of 9.8ft bution imp affect the p re shown in e contours f rall A-weig around the s are not as main repor truck of Fi -by Run 2 a d at the La (3m) above acting the v rofiles appr Figure D2. or the truck hted levels exhaust stac clearly cent t and D1 ab gure D2, it i t Lakeville keville test the ground. ertical profi oximately 6 Compared t of Figure D and the 40 k, which m ered on the ove, imply s also intere data. This le of .6 to o the 2 are 0 Hz ay be drive ing a sting
to note h most trai Another contours report. S but rathe the conto position contribut powertra from bot engine no and a so located a engine o testing. O indication beneath t ow the tires ler axle are h Figure D2: example fro of overall l imilar to Fig r about mid urs are eve of the 500 H ions from in/exhaust s h the drive ise sources urce is ind t the top of ccurs; so, it ut of 44 to of some a he cab. from each a igher than t Overall and m the Lakev evel are som ure D2, the way betwee n farther fo z contours a source(s ystem sourc axles and t with contou icated sligh the front ax is possible tal heavy-du mount of en xle of the tr he others. 400 Hz con ille site wo ewhat exp overall lev n the front rward on th of Figure 25 ) other th es. For 800 he trailer ti rs concentra tly more th le wheel w that during ty vehicles gine noise, D4 ailer are app tours of tru uld be Run 4 anded comp el contours and drive ax e tractor, es of the main an drive Hz, the noi res. At the ted below t an three fe ell. At these Run 44, the measured a most often, arent and al ck pass-by R 4, shown in ared to tho are not cen les of the tr pecially wh report. Th axle tires se appears t 3,150 Hz, t he cab betw et above th higher fre engine fan t the Lakevi at higher f so that the t un 10 at La Figure D3 se of Figure tered on the actor. For t en compare ese observat alone and o be domina here is furt een the fron e pavemen quencies, fa was runnin lle test site, requencies a ires from the keville . In this case 25 of the drive axle he 500 Hz b d to the rel ions imply likely du ted by tire her indicatio t and drive a t, approxim n noise from g at the tim virtually al nd coming rear , the main tires, and, ative noise e to noise n of xles, ately the e of l had from
Figu Other sp 11.5ft (3 ground to have a se 4.5m) ab 82.3 dBA a source re D3: Over ecial-case ru .5m) and ab less than 8 cond relativ ove the grou . Looking a in the vicini all, 500, 80 ns from the ove. Runs 0 dBA at he e maximum nd. The rel t the contou ty of the ex 0 and 3150 H Lakeville t such as Run ights below overall noi ative maxim r plots for R haust stack D5 z contours est site show 54 fall off 9.8ft (3m) a se level at h um levels un 54, as sh outlet in the of truck pas high over from the m s the above eights betw for these thr own in Fig overall lev s-by Run 44 all noise lev aximum no examples d een 11.5 an ee runs ran ure D4, ther el and in the at Lakevill els at heigh ise levels a id, but they d 14.8ft (3.5 ged from 81 e is indicati 2,000 Hz b e ts of t the each and .3 to on of and.
This sou and abou contribut and 4,00 source re noted wi exhaust g without h levels are Figu rce region i t 3 dB lowe e much to th 0 Hz bands gions and p th respect t as at the ou aving a ma 14 dB lowe re D4: Ove s about 9 dB r than the m e overall le (not shown roduces max o Figure D1 tlet. For ru jor impact r than the m rall, 1,000, lower than aximum in vel, it is su ), the source imum level , these high ns similar t on the verti aximum so and 2,000 H D6 the maxim the 2,000 fficiently str at the top s of 63 and frequency o Run 54, n cal distribut und level oc z contours o um of the Hz band. A ong to disto of the exhau 67 dBA in t sources are oise from t ion of noise curring at g f truck pass overall A-w lthough this rt the conto st stack do hese bands, likely due he exhaust , as the ov round level. -by Run 54 eighted con source doe urs. In the 3 minates all respectivel to jetting o outlet occur erall A-weig at Lakeville tours s not ,150 other y. As f the s but hted
The two different the maxim until heig small dim and 400 H F). Conto dominate octave ba acoustic level, it appears t result, it such as p Fi remaining profiles com um overal hts above 9 ension of t z) covered ur plots fo d by the 40 nd. The res wavelength is difficult t o be center cannot be d owertrain an gure D5: O runs with m pared to al l levels at th .8ft (3m). A he loudspea a considera r Run 17 ar 0 Hz band ultant area o and the stre o confirm t ed on the d etermined if d exhaust, o verall, 400, aximum n l other runs e ground. Th s discussed ker source, t ble area (see e shown in for which f the 400 H ngth of the he source o rive axle tir the large c r to unusua and 630 Hz D7 oise source , starting wi ese runs, R in regard to he noise co Figures 24 Figure D5. the level is z contour is source. Giv f the sound es for the o ontour area lly noisy tire contours of heights of th the rate o uns 17 and Figure 28 o ntours at the and 54 in th For this tru 10 dB high correspond en the large . In this cas verall level s are due to s. truck pass-b 12ft (3.7m f noise leve 45, do not re f the main r lower freq e main repo ck, the pas er than any ingly large area of the e, the highe and the 40 other, more y Run 17 at ) or above l reduction duce by 10 eport, despit uencies (i.e. rt and Appe s-by spectru other one- due to the lo maximum s st source re 0 Hz band. hidden sou Lakeville have from dBA e the , 315 ndix m is third nger ound gion As a rces,
D8 For the truck from Run 45, the one-third octave bands from 400 to 630 Hz have the highest level and are about equal. The 315 Hz band is about 6 dB lower in level. Contours for this truck are shown in Figure D6. As in the case of Run 55 (Figure 31 of the main report), the contours indicate that exhaust noise is a significant contributor to the pass-by level and shape of the vertical profile of the noise. Although lower than the 400 to 630 Hz bands, the 315 Hz contour most clearly demonstrates the presence of exhaust system noise. These contours are skewed upward at the exhaust stack, and the highest level is indicated between the front and drive axles about 5ft (1.5m) above the pavement. The 500 Hz band also shows the influence of the exhaust system as the contours virtually point to the exhaust stack. The overall contours are not as definitive for exhaust noise, as the highest source area is centered on the drive axle; although, there is a source region to the front of the truck that could be powertrain noise. In the 1,250 Hz contours, there is also a source region under the truck that has a height slightly greater than what would be expected for tire noise from the front axle. Out of 44 total heavy-duty vehicles measured at the Lakeville test site, three were identified as being heavily dominated by low frequency bands, which is approximately 6.8% of the total. Â Â
Figur 505 SB1 contour r During th creating (1m) apa those of indicates However e D6: Over Test Site. S esults, relat ese measur a slight rota rt, with the Figures 25 appreciable , typical 505 all, 315, 500 ome varian ive to the L ements, the tion in the c lowest line through 27 noise from SB1 result , and 1250 ce in source akeville sit microphone ontours. Th being pave from Lake the trailer s showed th D9 Hz contours distribution e. One exam array inad e larger hor ment level. ville in the tires, whic at the trailer of truck pas s were seen ple for Ru vertently ro izontal line In this case main repo h occurred tires played s-by Run 45 for the 50 n 8 is show tated about s in the grid , the contou rt. In partic often in the less of role at Lakevill 5 SB1 site i n in Figure 3° from ver are spaced rs are simil ular, Figur Lakeville , as indicate e n the D7. tical, 3.3ft ar to e D7 data. d by
D10 the overall A-weighted contours for Run 37 shown in Figure D8. In the 1,250 Hz band contours, engine noise from underneath the truck cab area is indicated, along with noise from the drive axle tires and trailer tires. The contours for the 630 Hz also indicate some contribution from sources other than tire noise. This band is the highest contributor to the overall level, but the source distribution is not centered on the drive axles, which also indicates additional sources, possibly from the exhaust system. Of the 41 heavy trucks that fall within the typical truck profiles at 505 SB1, the presence of engine noise was observed in 38. Nine of the 57 heavy-duty vehicle profiles from 505 SB1 reached their maximum height below 8.2ft (2.5m). This is lower than any of the 41 more typical trucks shown in Figure 29 of the main report. All of the trucks at 505 SB1 displayed some amount of tire noise, and most also indicated some powertrain/engine noise in front of the drive axles, extending to the front of the tractor in some cases. In all cases, any indication of powertrain/engine noise persisted close to the pavement level, and none is indicated at greater heights on the trucks. A typical contour plot from this grouping of data is shown in Figure D9 for Run 40. Compared to the contours of Figures D7 and D8, the contours for the overall level and the 800 Hz band are smaller, contributing to the lower profiles.
Figure D7: Overall, 630, 800, and 3150 D11 Hz contours of truck pass-by Run 8 at 505 SB1
Figure D8: Overall, 630, and 1250 Hz D12 contours of truck pass-by Run 37 a t 505 SB1
Fi There we extended heavy-du truck fro overall A the 1,600 cab and display s gure D9: Ov re also sev to heights ty measurem m Run 9 ar -weighted c Hz band. extending to imilar chara erall, 800, a en heavy-du above 13ft ents, five e shown in ontours in th Additionally the front cteristics. nd 1250 Hz ty vehicles (4m) befor were due to Figure D10 e vertical d , powertrai of the tracto D13 contours of measured a e reaching exhaust no . In this ca irection abo n/engine no r. Three of truck pass- t the 505 S their maxim ise. As an e se, the exha ve the cab a ise is indica the other r by Run 40 a B1 test site um height xample, the ust outlet n nd is seen in ted coming uns with ex t 505 SB1 with levels . Of these s contours o oise extend the contou from below haust noise that even f the s the rs for the also
Fi In two ru high leve the low f the 505 S affecting vehicles 505 SB2 at the La from trai case is s gure D10: O ns, the over ls stretching requency b B1 site, app the contou tested; and l Test Site. T keville site. ler tires as b hown in Fig verall, 630, all noise lev the height ands were d roximately rs; exhaust ow frequenc he contours As with the eing a signi ure D11, in and 1600 H els were dom of the vehi ifficult to d 88% of the m noise influ y bands affe for trucks a Lakeville r ficant source which the D14 z contours inated by l cle. The noi etermine. O easuremen enced was cted 3% of t 505 SB2 w esults, cont in almost a trailer tire of truck pas ow frequen se sources f the total h ts showed s approxima the vehicles ere genera our plots for ll plots for t contours are s-by Run 9 a cy noise con for cases wi eavy-duty v ome signific tely 9% of . lly similar to 505 SB2 in rucks with t about equ t 505 SB1 tent, which th high leve ehicles test ant engine all heavy those mea dicate tire railers. A ty al to the so have ls in ed at noise -duty sured noise pical urces
indicated contours of contou this case powertra Fig around th do indicate rs for a tru , tire noise i in noise from ure D11: Ov e tractor. In some power ck represent s clearly in underneat erall, 630, a this case, train noise ed in Figur dicated for t h the tractor nd 1600 Hz D15 no elevate coming from e 30 of the he drive ax and noise fr contours of d sources beneath th main report les and the om elevated truck pass- are indicate e tractor. A is shown in trailer tires, sources. by Run 131 d; however second exa Figure D1 as well as at 505 SB2 , the mple 2. In some
Fig Eleven o measurem site. In th reached t noise, wh contours the noise above the Lakeville noise lev ure D12: Ov f the heavy ents that y ese runs, n heir maxim ich is appro for Run 128 levels do n ground. Th site (Figure els ranging erall, 630, a truck noise ielded the h oise levels r ums at heig ximately 1 , which inc ot reduce l e contours 28 of the m from 69 to 7 nd 1250 Hz profiles sh ighest verti educed by hts of 11.5ft 0.2% of the lude exhaus ower than a for this run ain report) 2 dBA stret D16 contours of own in Fig cal distribut 10 dBA at h (3.5m) and 49 total hea t outlet nois profile no were similar . At 315 Hz ched the ent truck pass- ure 30 of th ion of nois eights of 8 above. Fiv vy-duty ve e, are shown ise level of to those sh for Run 12 ire height of by Run 133 e main rep e levels at t .5ft (2.6m) e of these ru hicles tested in Figure D 86 dBA w own above 8 at 505 SB the analysi at 505 SB2 ort represen he 505 SB2 and above. ns have ex at this site 13. In this ithin 16.4ft for Run 55 a 2, a large ar s window, a t the test They haust . The case, (5m) t the ea of nd in
D17 the 400 Hz frequency band (see Figure D13), there were two distinct ovals of levels: one at the drive axle tires of 72 dBA; and one at the top of the exhaust stack of 71 dBA. The highest source levels occur in the 500 Hz band, which appears to be due primarily to noise from the drive axle tires. As a result, the overall level contours are biased more toward pavement level where the contour level is 83 dBA, as opposed to 76 dBA at the top of the exhaust stack. In the 630 Hz band, the exhaust outlet source is again indicated, as it is for the frequency bands of 2,000 Hz and higher. Since the levels at 2,000 Hz and above are much lower than those of the contours shown in Figure D13, these higher frequency bands are not shown in the figure. The other six heavy-duty runs with elevated noise source heights at 505 SB2 had high levels at low frequency bands that impacted the overall levels. An example of the contours with this behavior are shown in Figure D14 for Run 119. These contours are also similar to those shown in Figure D5 from the Lakeville results and Figure D10 from 505 SB1. As in these previous cases, it is difficult to determine from the contours of Figure D14 what noise sources actually cause the results shown. In this example, the highest levels occur in the 315 Hz and 800 Hz bands. In the 800 Hz band, it appears that both the drive axle tires and powertrain noise contribute equally. Powertrain noise is also indicated by the 1,600 Hz band. The contours for the 315 Hz band fan upwards toward the top of the cab; however, in this and all other contours for this truck there are no explicit indications of elevated exhaust outlet noise.
Figur e D13: Overall, 400,500, and 630 H D18 z contours of truck pass-by Run 12 8 at 505 SB2
Figure D14: Overall, 315, 800, and 1600 D19 Hz contours of truck pass-by Run 119 at 505 SB2
D20 505 NB1 Test Site. Contours for one of the typical trucks (Run 62) from Figure 31 in the main report are shown in Figure D15. Consistent with the contours, this truck gives little indication of elevated noise sources. The highest levels are generated in the 315 Hz band contours; however, the contours are fairly low to the ground and very much centered on the drive axle tires. This is in contrast to those shown in Figure D14 for 505 SB2, which was identified as having elevated source heights. For Run 70, the 315 Hz contours indicate usually high drive axle tire noise levels for this frequency band. At 800 Hz, the contours begin to extend underneath the cab, with possible muffler noise contribution. At 1,250 Hz, the contours extend from between the drive axle tires to in front of the tractor, indicating more engine/powertrain noise contribution. There were 18 heavy-duty vehicles measured at 505 NB1 that resulted in high levels stretching as high above the ground as 9.8ft (3m) or more. Of the total number of heavy-duty vehicles measured at this site, 71 contained engine noise (97.3%); seven contained exhaust noise (9.6%); and 11 had high levels at low frequency bands that affected the overall noise levels (15.1%). The contours for Run 79, which includes exhaust and engine noise in addition to tire noise, are shown in Figure D16. This case is somewhat unique, as it only has a tractor and no trailer. Without any trailer tire noise, the position of the truck at the time of maximum level has the tractor directly opposite the array. In terms of the overall A-weighted contours, it is apparent that drive axle tire noise is the primary noise source. However, the contours do extend upwards to the top of the cab and indicate noise at the outlet of the exhaust stack. In the 315 Hz band contours, the highest levels are centered at the exhaust stack. Compared to the overall level and the other bands, however, the levels for 315 Hz band (58 dBA) are low, especially when compared to the 400 Hz band (68 dBA). The 400 Hz band is dominated by drive axle tire noise. As a result, the level for the tire noise in the overall contour is 75 dBA, while for the exhaust outlet the level is only about 67 dBA.
Figure D15: Overall, 315, 800, and 1250 D21 Hz contours of truck pass-by Run 62 at 505 NB1
Figu The seco at all fou around 1 that at 1 re D16: Ove nd example r Northern 1.5ft (3.5m) 1.5ft (3.5m) rall, 315, 40 taken from California . For Run 6 is about 3 0, and 630 Figure 35 of sites, this t 5, the differ dB; compar D22 Hz contours the main re ruck display ence betwee ed to 8 or 9 of truck pa port is Run s the high n the level dB at all ss-by Run 7 65. Of all th est overall at the pavem other sites, 9 at 505 NB e pass-by re level for he ent surface this differen 1 sults ights and ce is
extremely of exhau drive axl the exhau and is on measured from a hi Figur low. The c st stack nois e tires and t st stack. Ev ly 1 dB low in Norther ghway noise e D17: Over ontours for e, the conto he exhaust en at 800 H er than the h n California barrier. Th all, 400, 80 this truck a ur levels fo outlet. For t z, the exha ighest sourc , this is cle is was one o 0, and 1000 D23 re shown in r the overall he 400 Hz b ust outlet is e region for arly the wor ut of 224 tru Hz contour Figure D17 A-weighte and, the on equal to th tire noise f st case for cks, or abo s of truck pa . Unlike th d are equal ly source th e other sour rom the trai obtaining g ut 0.4% out ss-by Run 6 e other exam (80 dBA) fo at is indicat ces for the ler. Of the tr ood perform of this datab 5 at 505 NB ples r the ed is truck ucks ance ase. 1
