Figure 4. Iso-level contours developed with Cadna/A for the “loudest” scenario.
Sparing the reader full details of dB levels at loca- within defined pit areas along the main track,
tions near noise-sensitive receivers, property lines, but not the moving vehicles. Spread over the
and other geographical positions of interest, the entire area bounded by the track, much of the
model predicted that the Project, without mitigation, aggregate sound energy from the quantity of
would be in compliance with the aforementioned 55 racing vehicles would be unduly dissipated
dBA L
dn
guideline from the USEPA “levels document” before reaching the receivers.
as long as the proposed kart track was not in use, • Stationary point source – one might attempt to
and that only ten mobile sports cars would occupy define a curve in the track as being louder or
the main track. Unsurprisingly, at receivers near I-71, quieter than other locations, but this simply is
existing noise levels are already expected to exceed not a realistic depiction of track activity.
the 55 dBA L
dn
threshold and the Project is there- • Line source – unlike a heavily-traveled inter-
fore not expected to increase them by a significant state highway with a steady flow of traffic
degree—if at all. Predicted output sound levels from and noise generation, the track does not emit
TNM for I-71 were found to reasonably agree with the a continuous sound over its entire length at
Cadna/A prediction. any one time. Rather, it is the vehicles on the
track that are producing the sound and carry
5. DISCUSSION
the sources with them. And because there are
Without characterizing the Project’s anticipat-
nine possible track variations, not to mention
ed high-speed vehicles as moving point sources in
a wide variety of vehicle mixes to consider,
Cadna/A, the authors are doubtful an accurate model
limiting the sound propagation to a fixed line
would have been produced. Alternative methods for
suggests a narrow view of potential sound gen-
depicting these loud sources, even in Cadna/A, seem
eration scenarios.
ill-advised as follows:
Another important model feature was its con-
• Area source – appropriate for idling vehi-
straint to the actual site topography. A flat, reflective
cles that might position themselves anywhere
Continued on page 26
24 • Alumni Arsenal | November 2009 The Official Magazine of the NSBE Alumni Extension
Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42