number of events per hour (h-1); and V is the velocity 2.D. Potential Sources Not Included in Noise
of the vehicle (km/h). Model
The function of the Cadna/A model is to predict
Note that the aggregate sound from anticipated Project noise levels from sound sources which can rea-
sets of moving vehicles on each of the two tracks were sonably be expected to make a significant contribution
modeled as a quantity of point sources that travel to overall noise levels and for which we have reason-
along a closed circuit following the respective track able data or reference information to describe them.
geometry. The different quantities of moving vehicles Future sound sources that are likely to be associated
and idling vehicles modeled “at any one time” are with the Project, but do not meet this model inclusion
based on input received from Bluegrass Motorsports criteria are as follows:
and are represented as the following scenarios:
• Due to its members-only access, the Project is
1. Twenty sports cars on main track + ten karts not expected to create significant additional
on kart track traffic flows on I-71, Route 127 or local roads
2. Twenty sports cars on main track that will result in significant increases in sur-
3. Ten sports cars on main track + ten karts on
face transportation noise.
kart track
• Any transportation noise impacts resulting
4. Ten sports cars on main track
from changes to traffic flows on I-71 that are
5. Ten motorcycles on main track + ten karts on
attributed to Kentucky Speedway events are
kart track
not considered in the model. In general, a dou-
6. Ten motorcycles on main track
bling of traffic volumes would only produce a 3
7. Ten karts on main track
dB increase in the sound contribution from this
highway sound source.
For instance, if up to twenty-five cars may be at
• Although the administration building, garages
the main pit area with an average of fifteen, the model
and individual residences will likely all have
assumes the other ten must be on the track and mov-
heating, ventilation and air conditioning
ing at high speeds. Figure 3 shows a Cadna/A screen-
(HVAC) and other mechanical systems (e.g.,
shot of the input dialog box used to define the sports
pool pumps), the noise level amplitudes are
car sources in the model.
considered insufficient to impact the defined
noise-sensitive receivers over the distances
that these sounds must travel.
4. PREDICTION RESULTS
The results of the Cadna/A model calculations for
what one might label a “loudest” case (i.e., scenario
1, high-speed sports cars on the main track and simul-
taneous kart racing on the kart track) are graphically
depicted in Figure 4. This scenario assumes the main
track is occupied by twenty 750 HP sports cars mov-
ing at an average speed of 100 miles per hour, with
fifteen additional vehicles idling at two pit areas: ten
Figure 3. Sample Cadna/A “Line Source” input dialog, but with
at the “main pit” and five at the “back pit” (the one on
moving point source selected
the eastern end of the Property as shown in Figure 1).
Simultaneously, there are ten karts on the kart track
Speaking of idling vehicles in the main pit area, the
that is west of the main track, with its own five addi-
octave band sound power levels for a single station-
tional idling vehicles.
ary vehicle are based on sound pressure level (SPL)
measurements of a 2000 Chevrolet Camaro SS idling
at 1000 RPM, taken at 2 meters from muffled exhaust
tip, with the vehicle hood open.
The Official Magazine of the NSBE Alumni Extension November 2009 | Alumni Arsenal • 23
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