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