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Noooo Soooooo oo MoPoo PFC oo
Aoooooo Toooo
ADC40 2013 Summer Meeting
Manuel Trevino
Introduction • MoPac
– Busy urban highway – Pavement: dense-graded AC – Section in central Austin: PFC overlay to mitigate noise
– OBSI – SPL measurements
Project Location MoPac PFC
Austin, Texas
Project Location MoPac PFC
Austin, Texas Town Lake
Population and Traffic
Source: TxDOT
MoPac
MoPac (aka Loop 1)
PFC • Permeable Friction Course overlay constructed
summer 2010 – From RM 2222 to Town Lake – 1 ½ in.-thick – Southbound: PG 76-22 binder (PG-PFC) – Northbound: Asphalt-Rubber binder (AR-PFC)
OBSI Measurements • Noise measurements taken regularly
• Outside, middle, and inside lanes
• Three 440-ft subsections in each direction
OBSI Measurements
Before-After Comparison (Outside Lanes)
105.3
101.7
100
101
102
103
104
105
106
107
108
A B C D E H I J K L Avg
Ove
rall L
evel
(dB
A)
Southbound (PG Binder) Northbound (AR-PFC)
Before (DGAC), July 2010 After (PFC), September 2010
Southbound PFC
105.8 105.7 105.3
105.6 105.6 105.6
102.0 101.8
103.0
102.2 102.0
102.2
100
101
102
103
104
105
106
107
108
A B C D E Avg
Ove
rall L
evel
(dB
A)
PG-PFC
Before (DGAC) July 2010 After (PFC) September 2010
Northbound PFC
105.1 105.1 104.7
104.5
105.1 104.9
102.1
101.4 101.0
101.6 101.3 101.5
100
101
102
103
104
105
106
107
108
H I J K L Avg
Ove
rall L
evel
(dB
A)
AR-PFC
Before (DGAC) After (PFC)
Southbound PFC
65
70
75
80
85
90
95
100
105
400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000
Ove
rall L
evel
(dB
A)
1/3-Octave Band Center Frequency (Hz)
Before (DGAC) After (PFC)
Northbound PFC
65
70
75
80
85
90
95
100
105
400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000
Ove
rall L
evel
(dB
A)
1/3-Octave Band Center Frequency (Hz)
Before (DGAC) After (PFC)
98
99
100
101
102
103
104
105
106
1-SB 2-SB 3-SB SB - Avg 1-NB 2-NB 3-NB NB - Avg
Ove
rall L
evel
(dB
A)
Section Number
Southbound: PFC with PG76-22 binder Northbound: PFC with asphalt rubber binder
Outside Lane Middle Lane Inside Lane
Lane Comparison
96
98
100
102
104
106
108
Ove
rall
Leve
l (dB
A)
PG-PFC AR-PFC Dense-Graded
MoPac vs. Other Pavements (2012 Measurements)
• PFC provided an average reduction of 3.4 dBA, compared to DGAC
• NB (AR-PFC) significantly and consistently quieter than SB (PG-PFC)
• Middle lanes appear to be slightly louder, but differences are minimal
• PFC seems to have got quieter with time, but the slight decrease in noise levels could be attributed to 2012 tests being performed with a brand-new tire
Conclusions
• Compared to other sections, SB PFC is average among other PG PFCs in the state
• NB PFC is the quietest in the state, even quieter than the US 281 PFC in San Antonio, which for years had been the quietest PFC in Texas
Conclusions
SPL Measurements
• Continuous flow traffic time-integrated method (CTIM)
Normalizes for traffic variations using FHWA TNM (allows for comparison of data collected at different times)
Roadside Measurements
• Noise sources included: – Engine noise, exhaust noise – Aerodynamic sources – Adjacent vehicles – Non-traffic noise
– Railroad noise – Reflections
SPL Measurements
• Two SPL meters
• Video camera
• Speed radar
SPL Measurements
SPL Measurements
SPL Measurements
SPL Measurements
SPL Measurements • Summer testing
• Nine locations
• Two simultaneous measurements at each location – One next to highway (A) – One close to the residential
area (B)
• During non-peak hours
• Before and after PFC
Example: Sites 1 (SB) and 2 (NB)
Roadside Measurements (A)
Residential Measurements (B)
50
55
60
65
70
75
80
85
1A 1B 2A 2B 3A 3B 4A 4B 5A 5B 6A 6B 7A 7B 8A 8B 9A 9B
Soun
d Pr
essu
re L
evel
(dB
A)
Site
Before PFC (April-May 2010)
PFC (September-October 2010)
PFC (August 2011)
SPL Measurements
• PFC provided significant noise reduction at all sites compared to dense-graded AC
• PFC resulted in 6 to 7 dBA noise reduction, on average
• PFC continues to perform well acoustically
Conclusions
Acknowledgement • TxDOT, Austin District
• Mike Arellano, TxDOT Austin District Pavement Engineer
• John Wirth, TxDOT Construction Division/Materials & Pavements
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