Danish Traffic Noise Strategy Brian Kristensen Danish EPA Danish Ministry of the Environment
Two Layer Porous Asphalt - Danish Experiences - BRRC Seminar 2005
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Transcript of Two Layer Porous Asphalt - Danish Experiences - BRRC Seminar 2005
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Two-layer porous asphalt for urban roads
- The Øster Søgade projectLars Ellebjerg Larsen
Hans BendtsenDanish Road Institute/Road Directorate
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• To develop and test noise reducing pavements for urban roads
• Applying and improving Dutch two-layer concept for Danish conditions
• Investigate the clogging phenomenon of two-layer porous pavements
• Over the lifetime of the pavements to analyse:– The acoustical properties of the pavements– The clogging of the pavements– The structural properties of the pavements
Project goals
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AcknowledgementsØster Søgade experiment financed by:• Danish Ministry of Transport • Danish Ministry of the Environment
Danish project group: • Lene Michelsen, Danish Road Directorate • Steen Kønigsfeldt and Michael Rasmussen, Municipality of
Copenhagen• Jørn Bank Andersen, Pavement Contractors Association / NCC• Hans Bendtsen, Bent Andersen, Jørgen Kragh, Jørn Raaberg,
Bjarne Schmidt and Lars Ellebjerg Larsen, Danish Road Institute/Road Directorate
The clogging project: • Part of the Dutch IPG program• Financial and technical support and cooperation of Road and
Hydraulic Engineering Institute in the Netherlands (DWW) • The DRI-DWW noise abatement programme
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The test roadØster Søgade in Copenhagen:• Speed: 50 km/h• Traffic: 7000 AADT• HGV: 8 %• Length: 800 m
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The test road 2
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The porous pavements Name Section Type Total
thickness Top layer aggregate
Bottom layer
aggregate
PA8-70 I Porous asphalt 25+45 mm 5-8 mm 11-16 mm
PA5-55 II Porous asphalt 20+35 mm 2-5 mm 11-16 mm
PA5-90 III Porous asphalt 25+65 mm 2-5 mm 16-22 mm
DAC8 (ref.) IV
Dense asphalt
concrete30 mm 0-8 mm -
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The porous pavements 2
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0,001 0,01 0,1 1 10 100
Size (mm)
Per
cent
age
of m
ater
ial
AC8tDA5DA8DA16DA22
The test pavements
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The test pavements 2
Material PA5(top)
PA8(top)
PA16(bottom)
PA22(bottom)
DAC8(ref.)
Stone material 95.0 % 95.5 % 97.0 % 97.5 % 97.5 %
Hydrated lime 1.5 % 1.5 % 1.5 % 1.5 % 1.5 %
Lime filler 3.5 % 3.0 % 1.5 % 1.0 % 1.0 %
Cellulose fibers .25 % .25 % .25 % .25 %
Bitumen 6.3 % 5.4 % 3.9 % 3.5 % 5.8 %
Marshall cavity 25.5 % 26.0 % 25.5 % 25.5 % 2.4 %
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Pavement measurements
• On location– Texture – Laser measurements of MPD– Permeability – Becker’s tube method– Friction
• On drill cores– Built-in voids– Asphalt analyses– Thin and plane sections– CT-scans
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Noise measurements
• SPB• CPB• CPX• Sound absorption
– Extended surface method [ISO 13472-1]– Impedance tube – Transfer-function
method [ISO 10534-2]
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Other surveys
• Noise annoyance– questionnaire survey
• Cost-benefit analyses– Comparison of pavements, barriers and
façade insulation
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Texture
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Texture 2
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1,000
1,500
2,000
2,500
3,000
0,000 0,100 0,200 0,300 0,400 0,500 0,600 0,700
Positioning (km)
MP
D (m
m)
19992001200220042005Old pavement
PA8 PA5 DAC8
[ISO 13473-1]
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Permeability
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Permeability - northbound lane
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0 10 20 30 40 50 60 70
Months after opening
Wat
er d
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ing
time
(sec
onds
/10
cm)
PA8-70 aPA8-70 bPA8-70 cPA5-55 aPA5-55 bPA5-55 cPA5-90 aPA5-90 bPA5-90 c
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Permeability - southbound lane
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Months after opening
Wat
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time
(sec
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PA8-70 aPA8-70 bPA8-70 cPA5-55 aPA5-55 bPA5-55 cPA5-90 aPA5-90 bPA5-90 c
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CT-scan of porous asphalt
7 years old PA from A12
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CT-scan 2
33 mm
51 mm
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CT-Scan – Results
0%
10%
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70%
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100%
0 10 20 30 40 50 60 70
mm
VoidsMortarAggregate
Top layer (PA8)Bottom layer (PA16)
33 mm 51 mm
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100
mm
40 m
m
10 mm
10 mm
10 mm
Thin section 1
Thin section 2
Plane section (100 by 100 mm)
100 mm Drill Core
45 mm wide by 30 mm high
45 mm wide by 30 mm high
Preparation of plane sections
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Acquiring the images
Plane section: 100 x 100 mm
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Analyses of thin sections in microscope
New 4 years old
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SPB noise measurements
60
65
70
75
I II III IV
SP
BI'
[dB
]
1999 2000 2001 2002 2003 2004 2005
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Noise reduction
4.5 4.9
6.0
4.63.6 3.8
2.7 2.7 2.72.4 2.2
1.0
2.8
1.3 1.11.7
0.91.41.4 1.2
-0.2
-2
0
2
4
6
8
10
I II III
Noi
se re
duct
ion
[dB
]
1999 2000 2001 2002 2003 2004 2005
2.9 2.32.4
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Reference pavement – 8 or 11 mmL_pA, max, fast, 7.5 m as a function of speed
passenger cars, comparison of reference surfaces
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40 50 60 70Speed, [km/h]
L_pA
,max
,fast
,7.5
m, [
dB re
20
µPa]
AC8d, KglAC11d(E), KglAC8d, SFrAC11d, SFrAC11d, all, SFrAC11d, Ubh
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Questionnaire survey
• Questionnaire survey – before and after repaving– 240 questionnaires per survey– 72 and 65 percent returned
• Noise levels calculated with the Nordic Prediction Method for Road Traffic Noise– Levels before:
• +1 dB for a worn and uneven pavement– Levels after:
• -2.5 dB relative to before by the ref. pavement• -7.6 dB relative to before by the porous pavement
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Noise annoyance with closed windows
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Before After Before After
Reference pavement Porous pavement
Cannot hear noise fromroad traffic
Not annoyed
A little annoyed
Annoyed
Very annoyed
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Noise annoyance with openwindows
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Before After Before After
Reference pavement Porous pavement
Cannot hear noise fromroad traffic
Not annoying
A little annoying
Annoying
Very annoying
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Dose-response – closed windows
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
45 50 55 60 65 70 75
Noise outs ide windows - LAeq (dB(A))
A li
ttle
or
mo
re a
nn
oye
Before repaving
After repaving
Dose-response curve
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Cost-benefit analysis
Comparing 3 means:• Two-layer porous
asphalt• Noise barriers• Sound insulation
Net Present Value:• construction and
maintenance• costs for a 30-year
period
3 cases:• Central city street• Ring road• Freeway
Comparing:• Direct costs• Costs/dB/dwelling
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3 cases
City street (50 km/h, AADT: 12.000)Apartments: 1st – 5th floor65 – 68 dB façade level
Ring road (70 km/h, AADT: 30.000)Apartments: ground – 2nd floor73 – 74 dB façade level
Freeway (110 km/h, AADT: 60.000)Detached houses in 5 rows77 dB at the first row69/71 dB at the second row66/69 dB at the third row58/66 dB at the fourth row57/65 dB at the fifth row
15 m facade per apartment665 apartments (133/floor)
15 m facade per apartment399 apartments (133/floor)
23 m road per house435 houses (87/row)
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Porous pavements
Effect:
City street: 4 dB
Ring road: 5 dB
Freeway: 6 dB
Costs (net present value, €):
City street: 296,000
Ring road: 360,000
Freeway: 477,000
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Noise barriers
Effect:
City street: Not possible
Ring road: 0-12 dBAverage: 3.9 dB
Freeway: 1-12 dBAverage: 6.2 dB
Costs (net present value, €):
City street: Not possible
Ring road: 1,335,000
Freeway: 1,590,000
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Façade insulation
Effect:
9 dB on indoor levels with windows closed
Costs (net present value, €):
City street: 2,685,000
Ring road: 1,607,000
Freeway: 2,890,000
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Costs
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500
1000
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2000
2500
3000
3500
City street Ring road Freeway
Cost
s (t
housa
nd E
uro
Porous asphaltNoise barrierFacade insulation
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Costs per dB per dwelling
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900
City street Ring road Freeway
Cost
s/dB/
dw
ellin
g (
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Porous asphaltNoise barrierFacade insulation
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Conclusion and perspective• When new, the thickest porous pavement
with 5 mm aggregate had the best noise reduction of 5-6 dB
• When old the porous pavement with 8 mmaggregate in the top-layer maintain a noise reduction of 1-2 dB
• In relation to 11 or 16 mm dense asphalt reduction is 1 to 2 dB higher
• The pavement with 8 mm aggregate clogs significantly less than the pavements with smaller aggregate
• The PA5 pavements are “dead” in 2005
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Conclusions and perspective• The perceived effect of noise reductions by
porous asphalt matches the reduction in decibel level
• Compared to noise barriers and façade insulation porous asphalt gives a much higher noise reduction per invested Euro
• Analyses of thin and plane sections as well as the use of CT-scanning of drill cores will be used to evaluate the clogging process
• The working group are looking at possibilities for continuing the project with a renewal of the top layers with PA8