Improvement of Binocular Reconstruction Algorithm for Measuring 3D Pavement Texture Using a Single Laser Line Scanning Constraint

The dense and accurate measurement of 3D texture is helpful in evaluating the pavement function.To form dense mandatory constraints and improve matching accuracy,the traditional binocular reconstruction technology was improved threefold.First,a single moving laser line was introduced to carry out global scanning constraints on the target,which would well overcome the difficulty of installing and recognizing excessive laser lines.Second,four kinds of improved algorithms,namely,disparity replacement,superposition synthesis,subregion segmentation,and subregion segmentation centroid enhancement,were established based on different constraint mechanism.Last,the improved binocular reconstruction test device was developed to realize the dual functions of 3D texture measurement and precision self-evaluation.Results show that compared with traditional algorithms,the introduction of a single laser line scanning constraint is helpful in improving the measurement’s accuracy.Among various improved algorithms,the improvement effect of the subregion segmentation centroid enhancement method is the best.It has a good effect on both overall measurement and single pointmeasurement,which can be considered to be used in pavement function evaluation.

Characterization of pavement texture by means of height difference correlation and relation to wet skid resistance

Driving safety is of utmost importance in the automobile industry and is acknowledged by the introduction of the tire wet grip index as part of the EU tire label. The rubber pavement interaction is determined by the viscoelastic properties of the rubber as well as by the pavement texture. Nowadays available optical surface profiling instruments allow for a detailed measurement of surface roughness covering several length scales. This enables the validation of a mathematical statistical description of pavement texture within the framework of self-affine surfaces and hence provides a holistic characterization of surface roughness covering several length scales within a few characteristic parameters. We deduce within this article the correlation between classical surface roughness pa- rameters and the parameter set of self-affine surfaces. These parameters allow for a detailed understanding of the relationship between pavement texture and its wet skid resistance. We present wet skid resistance measurements with the British pendulum and a linear friction tester device on different pavement textures. We demonstrate that the so- called estimated texture depth does not correlate to the surface skid resistance measured with the British pendulum. Finally, we deduce a dependency of wet skid resistance on pavement texture which is supported by current models for hysteresis friction.

Simulation of vehicle braking behavior on wet asphalt pavement based on tire hydroplaning and frictional energy dissipation

To investigate the influence of wet conditions on vehicle braking behavior,a numerical-analytical method was proposed for the simulation of tire hydroplaning and frictional energy dissipation. First, a finite element model of tire hydroplaning was established using the coupled EulerianLagrangian method,including a pneumatic tire model and a textured asphalt pavement model. Then,the frictional force on the tire-pavement interface at different speeds was calculated by the model. Based on vehicle braking mechanism and frictional energy dissipation,a calculation method for braking distance was proposed based on a three-stage braking process. The proposed method was verified by comparing the calculated hydroplaning speed and braking distance with field test results.Then,vehicle braking distances and wet friction coefficients were calculated under different conditions. The results show that thinner water film,a more complex tread pattern and higher tire inflation pressure all contribute to the vehicle braking performance; moreover, the pavement texture has obvious influence on vehicle braking behavior,especially at a high speed. The proposed method shows great effectiveness in predicting vehicle braking behavior on wet asphalt pavements.

Evaluation of pavement skid resistance using high speed texture measurement

Skid resistance is an important parameter for highway designs, construction, management, maintenance and safety. The purpose of this manuscript is to propose the correlation between skid resistance, which is measured as skid resistance trailer, and mean profile depth （MPD） or the macro surface texture, which is measured by vehicle mounted laser, so that highway agencies can predict the skid resistance of pavement without the use of expensive and time consuming skid resistance trailer, which also causes disruption of traffic in use. In this research skid numbers and MPD from 5 new asphalt pavements and 4 old asphalt pavements were collected using a locked wheel skid trailer and a vehicle mounted laser. Using the data collected, a correlation between the skid number （SN40R） collected by locked wheel skid tester and the texture data or MPD collected by a vehicle mounted laser operating at highway speeds was developed. The proposed correlation for new pavements was positive for MPD values less than 0.75 mm to reach a peak SN40R value, then there was a negative correlation as the MPD increases until the MPD value was equal to 1.1 mm and beyond the MPD value of 1.1 mm to the maximum value of 1.4 mm, SN40R value remained almost constant. There were significant data scatter for the MPD value of 0.8 mm. To explain these results, water film thickness during the friction test was calculated and the critical MPD was defined. The effect of sealed water pool on the SN40R was discussed. The test result showed a similar trend for older asphalt pavements, but with lower SN40R values due to the polishing of pavement micro-texture by traffic. Hence, a reduction factor was proposed for older pavements based on cumulative traffic volume for the above correlation to predict the skid resistance of older pavements.

Pseudo feature point registration of pavement images

Over the last 20 years road pavement imaging has become a routine output from annual pavement assessment survey regimes across the world. Hitherto the traditional use of road pavement images in road condition assessment has been crack detection, rather than direct analysis of image features such as aggregate loss, changes in surface texture or deterioration of road markings. Any attempt to assess pavement condition change from features in a sequence of such images captured months or years apart requires image registration. A method for registering road pavement images is presented that makes use of an affine transformation based on pseudo-features within images. An affine trans- formation is considered suitable for registering road pavement images because of the linear way in which pavements are surveyed. Pseudo feature points are found using a modified corner detector, and then matching points between reference and template im- ages established via a correlation analysis of pavement image texture. With 4 such points it is possible to establish an affine transformation between the images. The method is tested on pavement images captured on three UK sites between winter 2014/15 and 2015/16. The method successfully registered 98% of images captured on sites typical of the UK＇s strategic road network, and 65% of images captured on a site typical of the UK＇s minor road network.

Noise emission of concrete pavement surfaces produced by diamond grinding

In Germany, diamond grinding is frequently used to improve the evenness and skid resistance of concrete pavement surfaces. Since diamond grinding has been observed to affect tyre/pavement noise emission favourably, the relationship among surface texture, concrete composition and noise emission of concrete pavement surfaces has been sys- tematically investigated. The simulation program SPERoN was used in a parameter study to investigate the main factors which affect noise emission. Based on the results of the simulations, textured concrete surfaces were produced by using a laboratory grinding machine. As well as the composition of the concrete, the thickness and spacing of the diamond blades were varied. The ability of the textured surfaces to reduce noise emission was assessed from the texture characteristics and air flow resistance of textured surfaces measured in the laboratory. It was found that concrete composition and, in particular, the spacing of the blades affected the reduction in noise emission considerably. The noise emission behaviour of numerous road sections was also considered in field investigations. The pavement surfaces had been textured by diamond grinding during the last years or decades. The results show that diamond grinding is able to provide good, durable noise- reducing properties. Several new pavement sections were investigated using thicknesses and spacings of the blades similar to those used in the laboratory to optimize noise emission reduction. It is concluded that diamond grinding is a good alternative to exposed aggregate concrete for the production of low-noise pavement surfaces.

A surface plasmon resonance imaging system for the stimulated living cell analysis

In this paper, a surface plasmon resonance imaging(SPRI) system for cell analysis is developed for obtaining the surface plasmon resonance(SPR) signal from the interactions between cells and different stimuli. The system is constructed with a red laser light source, a P-polarizer, a glass prism, a 5× objective lens, a charge coupled device(CCD) camera, a gold sensor chip, a polydimethylsiloxane(PDMS) reaction well and a mechanical scanning device. The system is applied to mapping living cells in response to stimuli by characterization of the refractive index(RI) changes. Cell responses to K+ in KCl solutions with concentrations of 5 mmol/L, 20 mmol/L, 50 mmol/L and 100 mmol/L are collected, which indicates that the SPRI method can distinguish the concentration of the stimuli. Furthermore, cell responses to epidermal growth factor(EGF) and vascular endothelial growth factor(VEGF) are studied independently. The binding of EGF receptor(EGFR) and EGF is collected as the first signal, and the internal change in cells is recorded as the second signal. The cell response to VEGF is different from that to EGF, which indicates that the SPRI as a label-free, real-time, fast and quantitative method has a potential to distinguish the cell responses to different stimuli.