67 Pa. Code § 157.41 - Site characteristics
(a)
Distances. Measurement shall be made at a test site which is
adjacent to, and includes a portion of, a traveled lane of a public highway. A
microphone target point shall be established on the centerline of the traveled
lane of the highway, and a microphone location point shall be established on
the ground surface not less than 26 feet (7.8 meters) or more than 118 feet
(35.4 meters) from the microphone target point and on a line that is
perpendicular to the centerline of the traveled lane of the highway and that
passes through the microphone target point. In the case of a standard test
site, the microphone location point shall be 50 feet (15.2 meters) from the
microphone target point. Within the test site shall be a triangular measurement
area. A plan view diagram of a standard test site, having an open site within a
50 foot (15.2 meters) radius of both the microphone target point and the
microphone location point, is shown in Figure 1 in Appendix A. Measurements may
be made at a test site having smaller or greater dimensions in accordance with
the provisions of Subchapter F (relating to correction factors).
(b)
Sound reflective objects in
triangular measurement areas. The test site shall be an open site,
essentially free of large sound-reflecting objects. However, the following
objects may be within the test site, including the triangular measurement area:
(1) Small cylindrical objects such as fire
hydrants or telephone or utility poles.
(2) Rural mailboxes.
(3) Traffic railings of any type of
construction except solid concrete barriers. See §
157.2 (relating to
definitions).
(4) One or more curbs
having a vertical height of one foot (0.3 meter) or less.
(c)
Sound reflective objects outside
triangular measurement area. The following objects may be within the
test site if they are outside of the triangular measurement area of the site:
(1) Any vertical surface, such as billboard,
regardless of size, having a lower edge more than 15 feet (4.6 meters) higher
than the surface of the traveled lane of the highway.
(2) Any uniformly smooth sloping surface
slanting away from the highway, such as a rise in grade alongside the highway,
with a slope that is less than 45° above the horizontal.
(3) Any surface slanting away from the
highway that is 45° or more and not more than 90° above the horizontal,
if all points on the surface are more than 15 feet (4.6 meters) above the
surface of the traveled lane of the highway.
(d)
Surface. The surface of
the ground within the measurement area shall be relatively flat. The site shall
be a "soft" test site. However, if the site is determined to be "hard," the
correction factor shall be applied to the measurement.
(e)
Pavement. The traveled
lane of the highway within the test site shall be dry, paved with relatively
smooth concrete or asphalt, and substantially free of:
(1) holes or other defects which would cause
a motor vehicle to emit irregular tire, body, or chassis impact noise;
and
(2) loose material, such as
gravel or sand.
(f)
Tunnel or underpass. The traveled lane of the highway on which
the microphone target point is situated shall not pass through a tunnel or
underpass located within 200 feet (61 meters) of that point.
Notes
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