Road Surface Texture Research Articles

Geometric Descriptors of Road Surface Texture in Relation to Tire-Road Noise

The paper deals with the determination of geometric parameters for studying the relationship between tire-road noise and texture of road surfaces. The approach was found to be an alternative to classical spectral analyses and numerical simulations of the tire-road contact. Texture parameters were derived from previous works at the Laboratoire Central des Fonts et Chaussées related to the influence of the microtexture of road surfaces on skid resistance. Use of these parameters was justified by consideration of generation mechanisms of rolling noise. Texture, rolling noise, and absorption measurements were performed on 12 road surfaces. The measuring devices and the test methods produced texture profile analyses, including the spectral and geometric approaches. Geometric parameters were defined. Correlation between the noise and texture spectra showed results similar to those published in previous works. Fair tendencies were found between the global noise level at 90 km/h and the geometric parameters. Unexpected results obtained on the porous asphalt surfaces were partially explained by the attenuation effect, which was quantified by means of existing models. Results from the correlation between the third-octave-band noise levels and the geometric parameters corroborated those of the spectral analyses.

MEASUREMENT OF ROAD SURFACE TEXTURE: AN EXAMINATION.

Keywords SOUTHAMPTON UNIVERSITY ROADS, SURFACES, TEXTURE, MEASUREMENT, TESTS, SAND, STANDARD, PATCH, METHODS, TOLERANCES, CONTRACTS, CONCRETE, SPECIMENS, TILES, BRUSHED, EXPOSED, AGGREGATES, FINISHES, TWO DIMENSIONAL, PROFILES, SKIDDING, RESISTANCE, MICROTEXTURE, MACROTEXTURE, PAVEMENTS, FLEXIBLE, RIGID, COMPOSITE, VARIATIONS, VARIABILITY... Show All

Hysteresis Friction of Sliding Rubbers on Rough and Fractal Surfaces

Abstract The friction force generated between sliding rubber and rough surfaces has two components commonly described as the adhesion and hysteretic components, respectively. Under wet conditions, the adhesion component of the total friction is drastically reduced, whereas the hysteresis loss remains largely unaffected. Such situations arise in daily life during blocked wheel braking where tire treads slide over wet road asperities. The situation becomes more complex in Anti Blocking System (ABS) braking on wet roads where both adhesion and hysteresis components of the friction force act. We present a new model of the hysteretic friction coefficient of a sliding rubber sample over a rough or even fractal surface. The model uses the basic assumption that the damping properties of the dynamically strained rubber depend on specific properties of the surface profile through its power spectral density. This assumption is based on recent findings that the fractal texture model is the only one developed to date to successfully address the complete multiscale behavior of paved road surface texture. The spectral density depends on the ‘topothesy’ k of the surface and scales with the spatial frequency f according to a power law. The corresponding power is related to the surface fractal dimension D. The quantities k and D are scale-independent parameters that characterize the multiscale self-affine topography of road surfaces in the characteristic length scale range of interest. The influence of surface roughness on the frictional properties of the rubber depends on the sliding velocity and is described through a retarded coupling between relaxational modes of the polymer network and roughness modes of the surface. The results of the theory are discussed in comparison with recent experimental results of Grosch. Finally, we demonstrate how the fractal descriptor parameters of different test road pavements are used to compare tire traction measurements performed on wet test roads.

Velocity Perception in 3-D Environments

Velocity perception has been investigated in many experiments with stimuli moving in the picture plane (2-D). For example, experiments with sine-wave gratings have shown that high-frequency patterns are perceived as moving faster than low-frequency patterns, and that high-contrast patterns are perceived as moving faster than low-contrast patterns. We investigated the influence of contrast and spatial frequency on perceived velocity in an open-loop driving simulation to determine whether contrast and spatial frequency account for differences in perceived velocity in complex 3-D environments. The simulated scene consisted of a textured road flanked by two meadows. We used road surface textures with different contrast and spatial frequency contents. In a 2AFC paradigm participants were simultaneously presented two driving simulation sequences depicting vehicles moving at different velocities on roads with different surface textures. Participants judged which vehicle was moving faster. Using an adaptive staircase procedure we determined the point of subjective equality for roads with different surface textures. The results show that perceived velocity in a driving simulation does depend on contrast and spatial frequency of the surface texture. Perceived velocity can be increased by increasing the contrast or the relative amount of high spatial frequencies in the surface texture. The relevance of these results for the design of driving simulators is discussed.

Development and Validation of a Method for Approximating Road Surface Texture-Induced Contact Pressure in Tire-Pavement Interaction

Abstract In tire-pavement interaction, road surface texture is an important variable that influences many properties such as tire noise, skid resistance, vehicle performance, and rolling resistance. Efforts to understand and quantify these texture effects have been limited by difficulties in experimentally and theoretically determining the many individual contact areas and contact pressures produced by irregularly-shaped asperities indenting the tire tread. The numerical method developed here to approximate the contact information is based on classical two-dimensional (2D) contact theory. The purpose of this paper is to describe this development. The method computes information on texture-induced contact pressure and length. The required inputs are 2D road surface texture data, tread rubber modulus, and tire inflation pressure. The approximated contact information is used to characterize road surfaces and advance understanding of how their textures affect tire-pavement interaction.

Vehicle Energy Dissipation Due to Road Roughness

SUMMARY Road roughness and surface texture are known to affect tire rolling resistance; however, little emphasis has been placed on the consequent changes in total vehicle energy dissipation due to road roughness. Thus, tire rolling resistance, in isolation from vehicle contributed losses such as dissipation in the suspension, appears to be a weakness in present evaluation procedures as they relate to fuel economy and pollution level testing: Recent work by Funfsinn and Korst has shown that substantial and measurable increases in energy losses occur for vehicles traveling on rough roads. The present investigation uses vehicle axle accelerations as a means of examining various road surfaces. Correlation with computer simulations has allowed the development of a deterministic road roughness model which permits the prediction of energy dissipation in both the tire and suspension as functions of road roughness, tire pressure, and vehicle speed. Comparison to the experiments of Korst and Funfsinn results in good agreement and shows that total rolling loss increases of up to 20 percent compared to ideal smooth roads are possible. The aerodynamic drag coefficient is also found to increase while driving on rough roads.

Wet Skid Resistance of Car and Truck Tires

Abstract Two test trailers for measuring tire characteristics are described. One of the trailers is specially built for testing car tires and can steer, camber, and brake the test tire. This trailer is provided with a five component measuring hub. The second trailer, for testing truck tires, is restricted to braking only. Braking forces are measured with a dynamometer. The determination of peak and locked wheel braking force coefficients is discussed. In addition, for car tires, a method for obtaining side force coefficients is given. Test results are given for both car and truck tires showing the influence of road surface texture, speed, and tread depth on skid resistance, and the results are compared.

A Basic Study of Automobile Tire Noise

The effects of various operating and conditional parameters of automobile tires, such as vehicle speed, vehicle load, inflation pressure, wear, size, and road surface texture, have been studied. Data were obtained in the field by coasting an automobile past a microphone varying one parameter at a time while keeping the others under rigid control. These data indicate that certain of these parameters, principally vehicle speed and road surface texture, more significantly influence the emitted noise than do the others.

The Effect of Road Surface Texture on Tire Wear

Abstract (1) This experimental work has shown that there is a large variation in the degree of tire wear on different surfaces, the wear on the rough, harsh surface being approximately three times as severe as that on the rough polished surface. (2) Measurement of weight loss by the method described provides a sensitive measurement of tire wear. (3) Qualitative analysis has shown that it is the harshness of the surface which is of major importance in tire wear, with surface roughness as a slightly modifying factor. (4) Quantitative analysis of various parameters indicating surface characteristics has shown that the shape of the asperity tips and the low-speed, wet coefficient of friction are major factors. These can be used to predict wear to a high degree of significance within the range of values covered by these measurements, although a large sample of surfaces would be desirable to check this relationship further. (5) A decrease in the severity of wear of six times involving a drop in speed from 50 km/h to 25 km/h has not altered the relative wear ratings of the three surfaces which have been compared and it seems reasonable to assume that the relative wear rates, although not the absolute values, would be the same in normal conditions of use. Consequently, the increased use of rough road surfaces is not expected materially to affect tire wear. (6) Significant increase in tire life from a wear standpoint can be expected from the use of radial ply tires instead of cross ply tires.

The effect of road surface texture on tyre wear : LOWNE, R. W. Wear, Vol 15, No 1 (Jan 1970) pp 57–70

The effect of road surface texture on tyre wear : LOWNE, R. W. Wear, Vol 15, No 1 (Jan 1970) pp 57–70

The effect of road surface texture on tyre wear

Most research on tyre wear has been carried out to determine the relative wear properties of different tread compounds and carcase constructions. This report describes tests which have been carried out to assess the effect of road surface characteristics on tyre wear. The work was prompted by the current trend towards harsher and rougher surfaces for improving wet-road skidding resistance. Two techniques for wearing tyres in a controlled manner were used: a fifth-wheel method in which the wheel was forced to run at a fixed slip angle and a method in which a vehicle was made to execute figure-of-eight manoeuvres thus wearing the test tyre which was fitted to a front wheel. The test surfaces were those on the Road Research Laboratory track which cover a wide range of texture and skidding resistance. Measurement of weight loss of the tyre was used to assess the wear. Increase in roughness of the surfaces was found to have a relatively small effect on wear, the major factor being surface harshness.

Discussion

Abstract Mr. W. B. Horne (NASA, Hampton, Virginia)—Results in the two papers are in agreement with NASA research results. The papers treated the subjects of tread material, tire construction, road surface texture, and tread design very thoroughly. But one essential ingredient to the problem has been left out of the paper discussions, and that is, the effect of water depth. The importance of the water depth effect, and the need to inform both public and government authorities about the importance of removing worn tires from automobiles for the safety of all, is discussed and illustrated very fully by Leland. An example of what happens when the water depth is 0.4 in. is shown in Figure 1. It can be seen that the water penetrates the tire imprint much more rapidly than in shallow water. The effect of road surface texture on braking friction coefficient is illustrated by the data shown in Figure 2. A smooth tread aircraft tire was successfully braked on five different road surfaces ranging in texture from a large aggregate asphalt surface to wet ice. These surfaces are classified as damp in wetness. The surfaces at the time of testing were wet to the touch but did not have any puddles or standing water. Under this condition, damp smooth concrete (smooth as a table top) gave friction values as low as wet ice. This drastic friction loss decreased as the road surface texture increased. It will be noted that the smooth aggregate asphalt data did not fall off in speed as was shown by Maycock in his paper in Figure 15. In Figure 3 the water depth on the smooth concrete and large aggregate asphalt surface was increased from a damp condition to a flooded condition (0.1–0.2 in.). The character of the friction changes of these surfaces due to change in water depth is remarkable. For example, the smooth concrete increased slightly in value. This is an apparent increase, however, because the deeper water produces a fluid drag term which adds to the tire-surface braking force and gives a higher friction coefficient. This is an academic point, however, since the smooth concrete surface is producing viscous hydroplaning even at low speeds. On the other hand, the asphalt surface which alleviated the viscous hydroplaning effect under damp conditions does not prevent dynamic hydroplaning from occurring to the tire when this surface is flooded to a depth of 0.1 to 0.2 in. To summarize, any surface must be evaluated under a range of water depths before its wet friction qualities can be properly evaluated. Smooth tread tires or badly worn patterned tires have demonstrated poor friction capabilities on most wet or flooded surfaces. For this reason, both aircraft and automobile tires should be removed and replaced before wear produces a smooth tread condition.

Paper 6: Tyre Forces as Functions of Cornering and Braking Slip on Wet Road Surfaces

The pure braking and cornering forces of a given tyre on a given wet surface at a given speed are functions of braking slip and slip angle respectively. These functional relationships are of great importance in connection with the handling and stability of vehicles and the behaviour of brakes and antilocking devices. When cornering and braking occur simultaneously the forces interact and the functional relationships are modified, with consequent effects on vehicle characteristics. The empirical data available at the Laboratory on these relationships, both for pure forces and for forces in combination, are presented. The known effects of such factors as speed, road surface texture, tread pattern, tread resilience, and tyre construction are reported, but since the work was carried out at various times and for various purposes the coverage is incomplete and uneven. The test vehicle, test procedure and the methods of measuring and evaluating the data are briefly described. Some data have been analysed statistically to discover the dependence of the various frictional coefficients on factors such as those mentioned above. It is believed that greater use should be made of these statistical techniques in future work. Raw data can also be converted into such practical quantities as braking distances, wheel locking times, etc., by computing theoretically the behaviour of model braking systems. An example of such a study is given. The principal features of the mutual effect of braking and cornering forces may be summarized as follows: (a) If curves of sideway force against slip angle are plotted for constant values of braking force, there is little change of initial slope, but the maximum sideway force and the slip angle at which it occurs are reduced. If, however, the curves are plotted for constant braking slip, then the initial slope is decreased and the slip angle for maximum sideway force is increased; at this same angle the sideway force at zero braking slip will only be slightly greater. (b) The presence of a fixed amount of angular slip reduces the initial slope of the curve of braking force against braking slip, reduces the maximum value of the force, and increases the slip at which it is attained. (c) In a few cases examined, if resultant force is plotted against resultant slip for a given speed, tyre, and surface, there is a tendency for the points to lie in a fairly definite band having a form similar to that of the braking force–braking slip curve.

Paper 2: The Road Surface and Safety of Vehicles

The control of a vehicle depends ultimately on the friction available between its tyres and the road surfaces to give adequate skidding resistance when wet under the many varied conditions of speed and road layout which are encountered in the course of normal driving. Methods of measuring the skidding resistance of road surfaces are described, with particular emphasis on the interpretation of results in relation to accident risk and on the minimum requirements for safety under different road conditions. The features of road surface texture which give these requirements are outlined and results of field surveys show the extent to which the requirements are met at the present time. The influence of tyre tread characteristics on the frictional properties of road surfaces is also discussed.

Influence of Test Conditions on Wet Skid Resistance of Tire Tread Compounds

Abstract This paper is primarily concerned with the skid behavior of tread compounds, and the extent to which testing parameters such as the type of road surface, the vehicle speed, or whether peak and sliding coefficients are considered, influence the skid behavior of one tread compound in relation to another. Whilst the actual braking coefficients depend profoundly on all these parameters the rating of two compounds is much less affected by them. Moreover, subject to the qualification given in the paper, the ranking of compounds will in many cases be predicted correctly by the RRL skid tester. The question arises how the rating of tread compounds will be affected by other testing methods. The three most commonly used are cornering, traction, and stopping distance tests. The first two are dominated by the peak value of the friction coefficient because the measurements are taken just before sliding occurs whilst the last reflects the sliding value of the braking coefficient. Since the rating is virtually the same for these two types of measurement it is likely to be independent of the measuring method. Although the ranking of compounds does not depend on the road surface, well drained road surfaces gave more reproducible results and larger ratings so that fewer readings are required on such a surface than on a flooded one. The following observations as to the nature of wet friction emerge from the present study. (a) Changes in coefficient of friction with tread compound and type of road surface texture confirm the findings of Miss Sabey, and Greenwood and Tabor, that the energy loss component of wet friction on coarse surfaces increases with the sharpness of the asperities, and thus with the pressure on the tops of the asperities. A mechanism for such energy losses based on elastic stored energy is suggested. (b) The decrease in the braking coefficient, as observed on well drained or dry road surfaces after the wheels have become locked, is explained by the frictional temperature rise in the area of contact. (c) It is suggested that in the case of the sliding tire, temperature increase in the contact region with increasing vehicle speed contributes to the observed fall in coefficient with increasing speed. This, together with the temperature dependence of the rubber properties, is used to explain small differences between the speed coefficients of various compounds in their rate of fall off with speed. (d) The mean braking coefficients of the compounds increase with their internal viscosity. It appears that the internal losses can be increased and therefore the skid resistance improved by incorporation of a heavy oil without an appreciable change in the glass transition temperature as measured by a torsion pendulum. This is strikingly demonstrated by the highly resilient natural rubber, whose skid resistance is greatly improved by oil extension without any significant loss in resistance to tire wear.

Road Surface Texture Prints

Road Surface Texture Prints