Friction measurement methods and the correlation between road - VTI

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Figure 3.5 Lateral friction force as a function of slip angle (from Gillespie[17]).Almost every country has its own friction-measuring device. Some devices aremore popular and are used by several countries, like the SCRIM (Side forceCoefficient Road Inventory Machine) or the Griptester. Many countries may haveseveral different devices for example for different purposes, one device for roadfriction screening measurements and one smaller device for measuring specialinteresting spots on the road system.A large number of friction measurement devices are listed in a report from1972 by Ohlsson et al. [41], see table 3.3. Since 1972 many things has changed.Today in Sweden, for example, the BV11 [40] is used instead of BV5 accordingto table 3.3, but generally the situation is the same with a variety of differentdevices in different countries and SCRIM as the most common device in Europe.The Swedish road friction devices used today are the BV11 [40] and the SFT(Saab Friction tester), see figure 3.6 and 3.7. Both are braking friction typedevices with a constant slip of about 17%. The test tyre used is a patternedstandard tyre, size 4.00-8 marked Trelleborg T49.Test wheelReferencewheelReference wheelLoadFigure 3.6 The Swedish skiddometer BV1114 VTI meddelande 911A
BV11 is a trailer with the water tank placed in the car. In the SFT themeasuring equipment is built into a normal passenger car which then also holdsthe water tank. Both BV11 and SFT are common friction measurement devicesfor airfields, with an alternative test tyre, actually they are much more common onairfields than on normal roads. There are a number of different versions of theSFT, e.g. the passenger car used as a base differs, but a recent comparisonbetween two different versions [37] concluded that the friction values could becompared on a one to one basis.VTI meddelande 911A 15
Page 1 and 2: VTI meddelande 911A • 2001Frictio
Page 3 and 4: Publisher:Publication:VTI meddeland
Page 5 and 6: ContentsAcknowledgementsSummary 51
Page 7 and 8: 1 IntroductionRoad friction, its me
Page 9 and 10: 3 Road friction measurementFriction
Page 11 and 12: 0,70,60,50,40,30,20,10Dense asphalt
Page 13: 3.1.1 Friction measurement devicesW
Page 17 and 18: Figure 3.7 The VTI Saab Friction Te
Page 19 and 20: Some devices use a fixed slip, like
Page 21 and 22: In Sweden mainly three friction mea
Page 23 and 24: 10 cmFigure 3.12VTI Portable Fricti
Page 25 and 26: The concept of international fricti
Page 27 and 28: Öberg [60] has compiled measuremen
Page 29 and 30: homogeneity of the surface conditio
Page 31 and 32: Figure 4.5 Accident rate (mean and
Page 33 and 34: Figure 4.7 Histograms of locked whe
Page 35 and 36: RoadwayappearanceDriverbehaviourAcc
Page 37 and 38: A number of surveys of friction num
Page 39 and 40: Figure 4.14 Multiplier for locked-w
Page 41 and 42: Table 4.2 Accident rates at differe
Page 43 and 44: 5 References1. Instructions for usi
Page 45 and 46: slitlagerbeläggning - inverkan på
Page 47: 50. Sävenhed H: Relation Between W

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