Appendices to NCHRP Research Report 842 (2017) / Chapter Skim
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From page 142... ...
H1 APPENDIX H MEDIUM TRUCKS DISCUSSION TABLE OF CONTENTS DISCUSSION OF MEDIUM TRUCK CONTOURS AND PROFILES ..............................H2 Northern California Test Sites .........................................................................................H2 North Carolina Test Sites ..............................................................................................
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From page 143... ...
A total o following trucks. Northern As shown Northern at these s North Ca which wa Figure H Californi Lakevill it is diff variation from the Figure H truck cas vehicle concentra centered DISCUS f 83 mediu Appendix California in Tables 3 California s ites.
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From page 144... ...
H3 second source region aligns with the muffler shown in the photograph, which is just behind the cab and low to the pavement. The highest one-third octave band levels occur in the 630 Hz contours, which clearly indicate drive axle tire noise as the source in this band.
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Figure H2: Overall, 630, and 800 Hz cont H4 ours of med ium truck pass-by Run 4 3 at Lakeville
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Figure H3: Overall, 630, and 800 Hz cont H5 ours of medium truck pass-by Run 24 at Lakeville
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Figure H Lakeville 505 SB2 505 SB2 truck pro increasin trucks, th 4: Overall, Site.
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From page 148... ...
H7 on the contours for this vehicle, which are shown in Figure H5, no elevated exhaust stack was apparent; however, there is a rack attached to the bed of the truck with an all-terrain vehicle mounted on it and protruding above the back of the truck cab. Aside from the elevated cargo noise source, the primary noise source for the medium truck of Run 109 appears to be from the drive axle tires, which seem to be quite pronounced in the 500 Hz band.
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From page 149... ...
Figure H SB2 5: Overall, 500, 800, and 3,150 Hz H8 contours of medium truck pass-by Run 109 at 505
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From page 150... ...
Figure 505 NB1 profiles f identical profiles f Lakeville least two tire and which ap out. The While th profile al noise, an H6: Overa Site.
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From page 151... ...
Figure H NB1 Compare that fall The diffe 7: Overall, d to the hea within the r rence in av 800, 1,250, vy trucks a ange measu erage measu and 2,000 H t this site, th red for the red speeds H10 z contours e medium heavy truck between he of medium truck runs r s, which wa avy and me truck pass-b educe by 10 s 5.2 to 8.9 dium is abo y Run 66 a dBA at he ft (1.6 to 2 ut 1 mph, w t 505 ights .7m)
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From page 152... ...
H11 may be contributing to the medium truck profiles showing similar behavior to the heavy trucks. Of course, the limited number of medium trucks measured at 505 NB1 limits the statistical relevance of the data set, which means that more trucks would have to be tested to determine if this pattern continues.
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From page 153... ...
Figure H in North Downhil in North truck at t at Site N Run 24 a sources a at height medium trucks, di noise dis Comparin shown in maximum heights r 2.3m) at noise sou indicated the avera level at N NC12 red at NC13 8: Overall A Carolina l Sites.
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From page 154... ...
The uphi had aver slightly h profiles r profiles a height ra resulted i pair. How measured Figure H sites in N Level Sit level gra figure do review o to be the mid-heig The rang trucks sh ll and down age maximu igher.
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From page 155... ...
Figure H in North Slower S indicate instance, Figure H had an a reduced f 3.4m) , w at height heavy tru have som would be had eleva the mediu low frequ The med average m average measured truck pro 3m)
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From page 156... ...
H15 this site that indicated the presence of elevated sources. Similar to NC8, however, one truck did have low frequency content.
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From page 157... ...
Figure H speed site 11: Overal s in North C l A-weighte arolina d levels for H16 all medium -duty vehicles measured at the slower
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