Use of the ASTM SRTT for Standardized OBSI Measurement

Transcription

1 Use of the ASTM SRTT for Standardized OBSI Measurement OBSI Workshop TRB 89 th Annual Meeting Paul R. Donavan Illingworth & Rodkin, Inc.

2 US Standard Test Tire Migration Goodyear Aquatred 3 P205/70R15 UniRoyal SRTT P225/60R16

3 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

4 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 & Europe n Can be ordered internationally n Relatively high cost tire

5 SRTT Specification n Durometer hardness Type A 64 ± 2 Equilibrium temperature 73.4ºF ± 3.6º Average of 4 ribs center rib excluded n Storage Not to exceed 70ºF Limit ozone exposure n Wheel rim width 6.5 ± 0.5 n Current cost ~ $400

6 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 n Pavements (7 total) DGAC one typical (two directions), one course OGAC two directions of travel PCC one longitudinally tined, one ground naverage of three runs

7 SRTT Test Tires (2007) Designation Manufacturer Date Purchase Date Application Km at Start Average Hardness SRTT #1 Oct-05 Mar-06 Secondary OBSI ~ SRTT #2 Oct-05 Mar-06 Primary OBSI ~ 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

8 Sound Intensity Level, dba SRTT Tire-to-Tire Variation (2007) Ranges SRTT #1 0.5 to 1.1 db SRTT #2 Average LF Passby Range Tire 0.8 db LR Passby Tire Average RF Passby Standard Deviation RR Passby 0.3 TiredB 96 DGAC EB OGAC EB OGAC WB DGAC WB Long. Tined PCC Ground PCC AC

9 SRTT Test Tires 2007 & 2008 Designation Manufacturer Date Purchase Date Application Km at Start Average Durometer SRTT #1 Oct-05 Mar-06 Primary OBSI ~ SRTT #2 Oct-05 Mar-06 Secondary OBSI ~ 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 SRTT #1 Oct-05 Mar-06 Secondary OBSI ~ RR Passby Jul-06 Oct-06 Passby tire ~ SRTT #3 Oct-07 Oct-08 New Backup 0 62

10 SRTT Tire-to-Tire Variation (2008) 104 RR Passby Tire (std dev = 0.2 db) 103 SRTT #3 (std dev = 0.3 db) Sound Intensity Level, dba to 1 Line Sound Intensity Level, dba - SRTT #1

11 Change in Noise over Time ntire durometer hardness (tire aging) Noise increases with hardness Hardness increases with aging Reported effect ~ 2 db per 10 durometer numbers Hardness increases at higher rate with exposure to higher temperature and ozone amounts ntread depth (tire wear) Inconsistent trends Results varying with test surface nvery limited data specific to the SRTT

12 Variation in Level 5/2007 to 10/2008 Sound Intensity Level, dba 106 SRTT # SRTT # RR Passby Tire 2007 RR Passby Tire DGAC EB OGAC EB OGAC WB DGAC WB Long. Tined PCC Ground PCC

13 Variation by Tire & Age Burlap Drag PCC SRTT 1 Passby SRTT SRTT 2 SRTT 3 NCHRP SRTT Overall OBSI Level, dba Apr 07 Oct 07 Nov 07 Oct 08 Oct 09 Date of Test

14 Variation by Tire & Age Overall OBSI Level, dba Ground PCC SRTT 1 Passby SRTT SRTT 2 SRTT 3 NCHRP SRTT Apr 07 Oct 07 Nov 07 Oct 08 Oct 09 Date of Test

15 Tire Comparsions Goodyear Aquatred 3 P205/70R15 Dunlop SP Winter Sport 3 P225/60R16 UniRoyal SRTT P225/60R16

16 Comparison of Tire OBSI Levels Aquatred (std dev = 0.3 db) 108 Dunlop M3 (std dev = 0.6 db) Sound Intensity Level, dba to 1 Line Sound Intensity Level, dba - SRTT

17 Comparison to SPB Results n12 sites measured nmix of AC and PCC nmeasured Statistical passbys for light vehicles Controlled passbys for test vehicle with SRTT tires nexamples for 7.5m microphone PCC longitudinally tines DGAC 5 years old Porous AC 1 year old

18 SRTT CPB & SPB Results - DGAC CPB with SRTT Light Vehicle SPB Sound Pressure Level, dba Speed, km/hr

19 SRTT CPB & SPB Results Porous AC 95 CPB with SRTT 90 Light Vehicle SPB Sound Pressure Level, dba Speed, km/hr

20 SRTT CPB & SPB Results PCC 95 CPB with SRTT 90 Light Vehicle SPB Sound Pressure Level, dba Speed, km/hr

21 SRTT CPB & SPB Results 12 Sites SPB Sound Pressure Level, dba Constant Offset Fit: Offset = 2.7 db Std Dev = 0.9 db y = 0.93x R 2 = CPB Sound Pressure Level, dba

22 OBSI & CPB for Hard Sites 25 ft Sound Pressure Level, dba Medium Texture Fine Texture Transverse Texture Constant Offset Linear Regression Slope =.94 R 2 = 0.94 Offset = 23.7 Std Dev = OBSI Level, dba

23 Summary: SRTT as a benchmark tire nlong term availability nrank orders pavements similar to other tires (lower absolute levels) nlow tire-to-tire variation Varies with pavement Average range of 6 tires = 0.8 db nperformance maintained under moderate usage up to at least 1½ years