Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter.
Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.
OCR for page 17
17
CHAPTER 5
Demonstration Testing of OBSI Procedure
Introduction were also tested. In addition, a highly porous rubberized AC
pavement along Shasta 299, about 5 miles east of Redding was
The investigation was conducted to demonstrate the ability tested. The site location, photographs of the pavement sec-
of the OBSI measurement method to quantify the relative tions, and the average 1/3 octave band spectrum for each sur-
effect of different pavement types in comparison to total vehi- face under baseline conditions are provided in Appendix D.
cle noise emissions measured with the CPB and SPB methods. All test sites followed the applicable criteria stipulated in the
It included the simultaneous measurement of (1) OBSI on spe-
FHWA document on highway noise measurement (20) and
cific candidate test tires, (2) controlled passbys on test vehicles
the ISO 11819-1 procedure (21). To the degree reasonable, sites
equipped with the test tires, and (3) statistical passbys of both
were selected to have acoustically hard (non-sound absorb-
light- and heavy-duty vehicles on in-service payments. Using
ing) surface characteristics between the vehicle lane of travel
the SPB data, the relationship between OBSI tire-pavement
and at least half of the distance to the 25-ft microphone fol-
noise and average vehicle noise emissions was examined for
lowing the ISO recommendation. Because the ISO procedure
both light vehicles and heavy trucks. To account for site-to-site
only addresses 25-ft distances, the FHWA criteria were used for
variation, passby results were normalized using the measured
the 50-ft microphone positions. To obtain comparable results,
relationships between OBSI and CPB levels for each site. This
sites were selected along roadways where the posted and typi-
chapter describes the measurements performed, the results of
cal vehicle speeds were 55 mph or higher. The designation,
the OBSI and passby testing, and the relationships between the
location, and description of each of the test sites are listed in
OBSI and passby data.
Table 6 (details of these sites are also provided in Appendix D).
Description of Field Measurements
Measurement Protocol
Measurement Sites
OBSI and controlled passby measurements were conducted
The OBSI and passby testing was conducted at a total of using the 2007 Pontiac Grand Prix and the 2007 Chevrolet
12 sites (five in Iowa and seven in California). The sites in Iowa Impala with Michelin/Uniroyal SRTT and Dunlop SP Winter
were located along U.S. Highway 30 between mileposts 178 and Sport M3 tires (Dunlop). The OBSI measurements followed
198, near Marshalltown. Portions of this section of highway the measurement protocol discussed for the parameter inves-
were recently constructed to include many different types of tigation using the two-probe approach (2) with a vehicle load
surface texturing (17). Along this section of highway, four sec- consisting of two people and the OBSI instrumentation. Mea-
tions with different PCC texture were selected as test sites, surements were conducted at 60 mph and at test speeds vary-
including a burlap drag surface, a random transverse tined ing from 50 to 70 mph, in 5-mph increments, depending on
surface, a uniformly tined surface, and a longitudinally tined the typical speed of on-road vehicles, in order to match the
surface. In addition, a nearby hot-mix AC pavement section speeds of the SPB measurements. The microphone signals were
was selected as a test site. In California, four of the Caltrans test acquired using the same instrumentation and data analysis sys-
sections on LA 138 (18), including DGAC, OGAC, rubber- tem described in Chapter 4. A standard 5-second averaging
ized, and bonded wearing course AC pavements were tested. time was used for test Sites 1 through 9 and 12; a 4-second
Two PCC sections, a grooved and a ground pavement, on the averaging time was used for Sites 10 and 11 because of the
Caltrans research sites on the Mojave Bypass (KN 58) (19) shorter lengths of pavement sections. During post-analysis,
