Use of the ASTM SRTT for Standardized OBSI Measurement€¦ · Use of the ASTM SRTT for...
Transcript of Use of the ASTM SRTT for Standardized OBSI Measurement€¦ · Use of the ASTM SRTT for...
Use of the ASTM SRTT for Standardized OBSI Measurement
Paul R. DonavanIllingworth & Rodkin, Inc..
OBSI WorkshopTRB 89th Annual Meeting
US Standard Test Tire MigrationGoodyear Aquatred 3
P205/70R15UniRoyal SRTT
P225/60R16
Issues for a Benchmark Tire
n Long term & international availability
n Variation between “identical” tires
n Change in noise generation over time
n Break-in & warm-up period
n Relationship to other, in-service tires
ATSM Standard Reference Test
Tire (SRTT)
n SRTT To be constructed for 10 years
n UniRoyal Tiger Paw brand, supplier is Michelin
n Use in the US & Europen Can be ordered
internationally n Relatively high cost tire
SRTT Specification
n Durometer hardness Type A – 64 ± 2Equilibrium temperature – 73.4ºF ± 3.6ºAverage of 4 ribs – center rib excluded
n Storage Not to exceed 70ºFLimit ozone exposure
n Wheel rim width – 6.5” ± 0.5”n Current cost ~ $400
Tire-to-Tire Variation
nSix tires of different age/mileage Two used in testing previously (~700 & 125 mi)Four new to be used for passby testing
nPavements (7 total)DGAC – one typical (two directions), one courseOGAC – two directions of travelPCC – one longitudinally tined, one ground
nAverage of three runs
SRTT Test Tires (2007)
Designation Manufacturer Date
Purchase Date Application Km at
StartAverage
Hardness
SRTT #1 Oct-05 Mar-06 Secondary OBSI ~ 1000 63
SRTT #2 Oct-05 Mar-06 Primary OBSI ~ 200 64
LF Passby Jul-06 Oct-06 Passby tire 0 64
LR Passby Jul-06 Oct-06 Passby tire 0 65
RF Passby Jul-06 Oct-06 Passby tire 0 64
RR Passby Jul-06 Oct-06 Passby tire 0 64
Date of Testing = May 2007
SRTT Tire-to-Tire Variation (2007)
96
97
98
99
100
101
102
103
104
105
DGACEB
OGACEB
OGACWB
DGACWB
Long.TinedPCC
GroundPCC
AC
Soun
d In
tens
ity L
evel
, dB
A
SRTT #1SRTT #2LF Passby TireLR Passby TireRF Passby TireRR Passby Tire
Ranges – 0.5 to 1.1 dBAverage Range – 0.8 dBAverage Standard Deviation – 0.3 dB
SRTT Test Tires – 2007 & 2008
Designation Manufacturer Date
Purchase Date Application Km at
StartAverage
Durometer
SRTT #1 Oct-05 Mar-06 Primary OBSI ~ 1000 63
SRTT #2 Oct-05 Mar-06 Secondary OBSI ~ 200 64
LF Passby Jul-06 Oct-06 Passby tire 0 64LR Passby Jul-06 Oct-06 Passby tire 0 65
RF Passby Jul-06 Oct-06 Passby tire 0 64
RR Passby Jul-06 Oct-06 Passby tire 0 64SRTT #1 Oct-05 Mar-06 Secondary OBSI ~ 2000 66
RR Passby Jul-06 Oct-06 Passby tire ~ 300 63
SRTT #3 Oct-07 Oct-08 New Backup 0 62
SRTT Tire-to-Tire Variation (2008)
97
98
99
100
101
102
103
104
97 98 99 100 101 102 103 104
Sound Intensity Level, dBA - SRTT #1
Soun
d In
tens
ity L
evel
, dB
A
RR Passby Tire (std dev = 0.2 dB)
SRTT #3 (std dev = 0.3 dB)
1 to 1 Line
Change in Noise over Time
nTire durometer hardness (tire aging)Noise increases with hardnessHardness increases with agingReported effect ~ 2 dB per 10 durometer numbersHardness increases at higher rate with exposure to higher temperature and ozone amounts
nTread depth (tire wear)Inconsistent trendsResults varying with test surface
nVery limited data specific to the SRTT
92
94
96
98
100
102
104
106
DGAC EB OGAC EB OGAC WB DGAC WB Long. TinedPCC
Ground PCC
Soun
d In
tens
ity L
evel
, dB
A
SRTT #1 2007SRTT #1 2008RR Passby Tire 2007RR Passby Tire 2008
Variation in Level 5/2007 to 10/2008
Variation by Tire & Age
97
98
99
100
101
102
103
104
105
Apr 07 Oct 07 Nov 07 Oct 08 Oct 09Date of Test
Ove
rall
OB
SI L
evel
, dB
A
SRTT 1 Passby SRTTSRTT 2 SRTT 3NCHRP SRTT
Burlap Drag PCC
Variation by Tire & Age
97
98
99
100
101
102
103
104
105
Apr 07 Oct 07 Nov 07 Oct 08 Oct 09Date of Test
Ove
rall
OB
SI L
evel
, dB
A
SRTT 1 Passby SRTT
SRTT 2 SRTT 3
NCHRP SRTT
Ground PCC
Tire ComparsionsGoodyear Aquatred 3
P205/70R15UniRoyal SRTT
P225/60R16
Dunlop SP Winter Sport 3 P225/60R16
Comparison of Tire OBSI Levels
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
95 96 97 98 99 100 101 102 103 104 105 106 107 108 109
Sound Intensity Level, dBA - SRTT
Soun
d In
tens
ity L
evel
, dB
A
Aquatred (std dev = 0.3 dB)
Dunlop M3 (std dev = 0.6 dB)
1 to 1 Line
Comparison to SPB Results
n12 sites measured nMix of AC and PCCnMeasured
Statistical passbys for light vehiclesControlled passbys for test vehicle with SRTT tires
nExamples for 7.5m microphonePCC – longitudinally tinesDGAC – 5 years oldPorous AC – 1 year old
SRTT CPB & SPB Results - DGAC
65
70
75
80
85
90
95
70 80 90 100 110 120 130
Speed, km/hr
Soun
d Pr
essu
re L
evel
, dB
A
CPB with SRTT
Light Vehicle SPB
SRTT CPB & SPB Results – Porous AC
65
70
75
80
85
90
95
70 80 90 100 110 120 130
Speed, km/hr
Soun
d Pr
essu
re L
evel
, dB
A
CPB with SRTT
Light Vehicle SPB
SRTT CPB & SPB Results – PCC
65
70
75
80
85
90
95
70 80 90 100 110 120 130
Speed, km/hr
Soun
d Pr
essu
re L
evel
, dB
A
CPB with SRTT
Light Vehicle SPB
SRTT CPB & SPB Results – 12 Sites
70
72
74
76
78
80
82
84
86
88
90
70 72 74 76 78 80 82 84 86CPB Sound Pressure Level, dBA
SPB
Sou
nd P
ress
ure
Leve
l, dB
A
Constant Offset Fit:Offset = 2.7 dB
Std Dev = 0.9 dB
y = 0.93x + 7.81R2 = 0.93
OBSI & CPB for “Hard” Sites – 25 ft
66
68
70
72
74
76
78
80
82
84
88 90 92 94 96 98 100 102 104 106 108OBSI Level, dBA
Soun
d Pr
essu
re L
evel
, dB
A
Medium Texture
Fine Texture
Transverse Texture
Constant Offset
Linear Regression
Slope = .94R2 = 0.94Offset = 23.7Std Dev = 0.9
Summary:
SRTT as a benchmark tire
nLong term availabilitynRank orders pavements similar to other tires
(lower absolute levels)nLow tire-to-tire variation
Varies with pavementAverage range of 6 tires = 0.8 dB
nPerformance maintained under moderate usage up to at least 1½ years