Friction of Rubber Wheels on Wet Asphalt Surfaces

2008 ◽  
Author(s):  
Noamen Bouzid ◽  
Bodo Heimann
Keyword(s):  
Water Film ◽  
Experimental Investigations ◽  
Test Surface ◽  
Automotive Safety ◽  
Friction Process ◽  
The Road ◽  
High Speeds ◽  
Vehicle Velocity ◽  
On The Road ◽  
Velocity Water

A reliable online prognosis of the grip between tire and road is a feature with a big potential for further improvements of the automotive safety. Existing grip potential prognosis systems for wet conditions are able only to describe the hydrodynamic decrease of friction at high speeds which depends on vehicle velocity, water film thickness and drainage properties both of the road surface and the tire. The present work deals with the friction at low speeds which depends on the road micro roughness. The experimental investigations are done in laboratory using a small solid rubber wheel and several asphalt samples. All parameters possibly influencing the friction process are varied. The influence of the test surface is found to be related to the micro texture and to be independent of any other parameters.

Analysis of Vehicle–Pedestrian Interactive Behaviors near Unsignalized Crosswalk

2021 ◽  
pp. 036119812199906
Author(s):  
Byeongjoon Noh ◽  
Dongho Ka ◽  
David Lee ◽  
Hwasoo Yeo
Keyword(s):  
South Korea ◽  
Traffic Accidents ◽  
Road Traffic ◽  
The Road ◽  
Video Footage ◽  
Premature Deaths ◽  
Vehicle Velocity ◽  
Behavioral Features ◽  
Velocity Changes ◽  
On The Road

Road traffic accidents are a leading cause of premature deaths and globally pose a severe threat to human lives. In particular, pedestrians crossing the road present a major cause of vehicle–pedestrian accidents in South Korea, but we lack dense behavioral data to understand the risk they face. This paper proposes a new analytical system for potential pedestrian risk scenes based on video footage obtained by road security cameras already deployed at unsignalized crosswalks. The system can automatically extract the behavioral features of vehicles and pedestrians, affecting the likelihood of potentially dangerous situations after detecting them in individual objects. With these features, we can analyze the movement patterns of vehicles and pedestrians at individual sites, and understand where potential traffic risk scenes occur frequently. Experiments were conducted on four selected behavioral features: vehicle velocity, pedestrian position, vehicle–pedestrian distance, and vehicle–crosswalk distance. Then, to show how they can be useful for monitoring the traffic behaviors on the road, the features are visualized and interpreted to show how they may or may not contribute to potential pedestrian risks at these crosswalks: (i) by analyzing vehicle velocity changes near the crosswalk when there are no pedestrians present; and (ii) analyzing vehicle velocities by vehicle–pedestrian distances when pedestrians are on the crosswalk. The feasibility of the proposed system is validated by applying the system to multiple unsignalized crosswalks in Osan city, South Korea.

scholarly journals THE EXPERIMENTAL STUDY OF SHALLOW FLOWS OF LIQUID ON THE AIRPORT RUNWAYS AND AUTOMOBILE ROADS

Transport ◽  
2010 ◽  
Vol 25 (4) ◽  
pp. 394-402 ◽  
Author(s):  
Andrey Beljatynskij ◽  
Olegas Prentkovskis ◽  
Julij Krivenko
Keyword(s):  
Experimental Study ◽  
Traffic Safety ◽  
Water Film ◽  
Reynolds Numbers ◽  
Road Surface ◽  
Moving Vehicle ◽  
The Road ◽  
Shallow Flows ◽  
On The Road ◽  
Effective Water

Hydroplaning or aquaplaning is associated with the complete loss of the grip of a tyre because of the presence of a water film between the tyres of a moving vehicle (an automobile, an airplane, etc.) and the road surface. In this case, a vehicle becomes uncontrollable. Hydroplaning (aquaplaning) occurs when the speed of a vehicle reaches the critical value, when the wheel does not have time enough for water compulsion, which leads to the formation of a permanent water film between it and the road surface. The higher the depth of the water on the road surface under the tyre, the higher the risk of hydroplaning (aquaplaning). In other words, hydroplaning (aquaplaning) is the floating of the wheel on the water wedge. In physical terms, it is the loss of the ability of a tyre of the effective water compulsion from the contact area with the road. As a result, a water film of several millimeters is formed under the wheel, and a vehicle actually floats up. The article presents the results obtained in the experimental study of the flows of liquid, whose depth is comparable with that of depressions and cambers of rough roadway pavement. It is stated that the relationships used for calculating surface flows should be corrected for shallow flows, taking into account the actual roughness of road covering. Shallow flows are mostly laminar. The transition Reynolds numbers are about 3000. The relationships used for calculating shallow flows may be determined more accurately by test pouring of water on the surface of roadway pavement, with further generalization of the data. The experimental research performed is closely related to the study of the problems of aquaplaning and traffic safety of various means of transport.

Road wetness quantification via tyre spray

2018 ◽  
Vol 233 (1) ◽  
pp. 28-37 ◽  
Author(s):  
Bernhard Schmiedel ◽  
Frank Gauterin ◽  
Hans-Joachim Unrau
Keyword(s):  
Vehicle Dynamics ◽  
Autonomous Vehicles ◽  
Water Film ◽  
Significant Loss ◽  
Vehicle Speed ◽  
The Road ◽  
Acceleration Sensors ◽  
On The Road ◽  
Wheel Arch

Road wetness can lead to a significant loss in tyre traction. Although a driver can easily distinguish between dry and wet roads, the thickness of a water film on the road (wetness) and its impact on the vehicle dynamics are more difficult for a driver to classify. Furthermore, autonomous vehicles also need a graded classification of road conditions. There are known sensors, which are able to classify road conditions, but these are either not able to quantify the road wetness or are not suitable for mass production. Therefore, this work analyses a method to measure the road wetness by analysing tyre spray with plain acceleration sensors at positions like wheel arch liner or side skirt. It discusses influences of vehicle speed, road wetness, tyres, road structure and sensor positioning. The results show that a quantification of road wetness is possible, but it relies on the sum of all boundary conditions.

Development and Performance of the Portable Skid Resistance Tester

1965 ◽  
Vol 38 (4) ◽  
pp. 840-862 ◽  
Author(s):  
C. G. Giles ◽  
B. E. Sabey ◽  
K. H. F. Cardew
Keyword(s):  
Field Trials ◽  
Test Surface ◽  
Skid Resistance ◽  
Textured Surfaces ◽  
Basic Principles ◽  
The Road ◽  
Factors Influencing ◽  
On The Road ◽  
And Performance ◽  
Patterned Tire

Abstract The portable skid-resistance tester can carry out a wide variety of measurements on the road and in the laboratory. This paper outlines the basic principles underlying the design of the tester and describes the laboratory and field trials conducted during the development of the instrument. The factors influencing its performance are emphasized. In its performance, the instrument behaves as a patterned tire skidding at 30 mph. It is particularly well suited for testing rough-textured surfaces, and readings are independent of gradient, camber, or crossfall on the test surface.

Road Surface Characteristics and Skidding Resistance

1967 ◽  
Vol 40 (3) ◽  
pp. 684-693 ◽  
Author(s):  
Barbara E. Sabey
Keyword(s):  
Large Scale ◽  
High Pressures ◽  
Water Film ◽  
Surface Characteristics ◽  
Road Surface ◽  
Dominant Factor ◽  
Fine Scale ◽  
The Road ◽  
Drainage Channels ◽  
On The Road

Abstract When roads are wet their skidding resistance is reduced by the lubricating action of the film of water on the road. Under some circumstances this reduction may be substantial and the extent of it is largely dependent on the characteristics of the road surface. The first requirement for a good skidding resistance on wet roads is to facilitate break through of the water film in order to establish areas of dry contact between the road and the tire. Drainage channels, provided by the large scale texture of the road or by a pattern on the tire, assist in getting rid of the main bulk of water and are of increasing importance the higher the speed. The penetration of the remaining water film can be achieved only if there are sufficient fine scale sharp edges in the road on which high pressures (about 1000 lb/in2) are built up. The existence of such fine scale sharpness gives the surfaces a harsh feel. When vehicles are travelling at speeds of about 30 mph the fine scale texture of the road is the dominant factor determining skidding resistance. However, as they travel faster, it becomes increasingly difficult to penetrate the water film in the time available, however harsh the surface. At high speeds the requirements for a good skidding resistance are therefore different. The resistance to skidding arises to a larger extent from energy losses in the rubber of the tire as the surface of the tread is deformed by projections in the road surface and, although the physical properties of the tread rubber are important in this respect, it is essential to have sufficiently large and angular projections in the road surface to deform the tread, even though a water film may still be present on the surface. At higher speeds the coarseness of texture becomes as important as its harshness.

scholarly journals Vehicle Velocity Relation to Slipping Trajectory Change: An Option for Traffic Accident Reconstruction

2018 ◽  
Vol 30 (4) ◽  
pp. 395-406 ◽  
Author(s):  
Vidas Žuraulis ◽  
Edgar Sokolovskij
Keyword(s):  
Initial Velocity ◽  
Traffic Accident ◽  
Experimental Tests ◽  
Accident Reconstruction ◽  
Slip Mode ◽  
The Road ◽  
Vehicle Velocity ◽  
Computer Aided ◽  
Velocity Relation ◽  
On The Road

In this paper, the relation of the velocity of a vehicle in the slip mode to the parameters of the tire marks on the road surface is examined. During traffic accident reconstructions, the initial velocity of a sideslipping vehicle is established according to the tire mark trajectory radius, and calculations highly depend on the directly measured parameters of the tire marks, in particular cases known as yaw marks. In this work, a developed and experimentally validated 14-degree-of-freedom mathematical model of a vehicle is used for an investigation of the relation between velocity and trajectories. The dependence of initial vehicle velocity on tire yaw mark length and trajectory radius was found as a characteristic relation. Hence, after approximation of the permanent slipping part by a polynomial, the parameters of the latter were related to vehicle velocity. The dependences were established by specific experimental tests and computer-aided simulation of the developed model.

Weigh-in-Motion System Testing

2012 ◽  
Vol 518 ◽  
pp. 428-436 ◽  
Author(s):  
Krzysztof Sekuła ◽  
Andrzej Świercz
Keyword(s):  
Deformable Body ◽  
Measurement Techniques ◽  
Field Tests ◽  
Load Identification ◽  
The Road ◽  
Motion System ◽  
Weigh In Motion ◽  
Vehicle Velocity ◽  
On The Road ◽  
Involved Field

The paper presents some results of research on the Weight-in-motion (WIM) system. The device is used for identification of loads on the road surface generated by traveling vehicles. The proposed approach utilizes the piezoelectric measurement techniques to monitor strain development in a deformable body and eventually these measurements are used for tire-pavement load identification. An advantage of the proposed concept is that no additional limitation for a vehicle velocity and direction is required in order to make the measurement feasible. The device allow to identify many parameters which can be stored for statistical and planning purposes. When an overload or an exceed in speed limit is detected the data can be sent for penalization purposes. The research includes a computer simulation of the bending plate detector using the Finite Element Method (FEM). Its objective is to validate the concept as well as to test some factors which are important with respect to the proposed load identification methodology. An experimental research involved field tests on the WIM system using a bending plate detector and inductive loops to detect a vehicle.

Large Eddy Simulation Investigation of the Hysteresis Effects in the Flow Around an Oscillating Ground Vehicle

2011 ◽  
Vol 133 (12) ◽  
Author(s):  
Siniša Krajnović ◽  
Anders Bengtsson ◽  
Branislav Basara
Keyword(s):  
Vertical Axis ◽  
The Body ◽  
Experimental Investigations ◽  
Flow Conditions ◽  
Ground Vehicle ◽  
The Road ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Flow Mechanisms ◽  
On The Road

This paper presents large eddy simulations (LES) of flow around a simplified vehicle model oscillating around its vertical axis. The frequency of the Strouhal number St = 0.068 and a relatively small amplitude of the oscillation are chosen to be representative for the crosswind conditions of vehicles on the road. The results were found to agree well with data from previous experimental investigations. Furthermore, the differences in LES flows between quasi-steady and dynamic flow conditions are presented and underlying flow mechanisms are explored. The cause of the phenomena of hysteresis and phase shift was found in the inertia of the flow to adjust to sudden changes in the direction of the oscillation of the body.

scholarly journals A Study on Distance Measurement Module for Driving Vehicle Velocity Estimation in Multi-Lanes Using Drones

2021 ◽  
Vol 11 (9) ◽  
pp. 3884
Author(s):  
Kwan-Hyeong Lee
Keyword(s):  
Estimation Method ◽  
Distance Measurement ◽  
Velocity Estimation ◽  
Detection Distance ◽  
Measuring Point ◽  
Measuring Device ◽  
The Road ◽  
Vehicle Velocity ◽  
On The Road ◽  
Vehicle Information

A method of estimating driving vehicle information usually uses a speed gun and a fixed speed camera. Estimating vehicle information using the speed gun has a high risk of traffic accidents by the operator and the fixed speed camera is not efficient in terms of installation cost and maintenance. The existing driving vehicle information estimation method can only measure each lane’s driving vehicle information, so it is impossible to measure multi-lanes simultaneously with a single measuring device. This study develops a distance measurement module that can acquire driving vehicle information in multi-lanes simultaneously with a single system using a drone. The distance measurement module is composed of two LiDAR sensors to detect the driving vehicle in one lane. The drone is located above the edge of the road and each LiDAR sensor emits the front/rear point of the road measuring point to detect the driving vehicle. The driving vehicle velocity is estimated by detecting the driving vehicle’s detection distance and transit time through radiation, with the drone LiDAR sensor placed at two measurement points on the road. The drone LiDAR sensor radiates two measuring points on the road and estimates the velocity based on driving vehicle’s detection distance and driving time. As an experiment, the velocity accuracy of the drone driving vehicle is compared with the speed gun measurement. The vehicle velocity RMSE for the first and second lanes using drones is 0.75 km/h and 1.3 km/h, respectively. The drone and the speed gun’s average error probabilities are 1.2% and 2.05% in the first and second lanes, respectively. The developed drone is more efficient than existing driving vehicle measurement equipment because it can acquire information on the driving vehicle in a dark environment and a person’s safety.

Community Colleges: Vital Partners on the Road to Diversity

ASHA Leader ◽  
2006 ◽  
Vol 11 (5) ◽  
pp. 14-17 ◽  
Author(s):  
Shelly S. Chabon ◽  
Ruth E. Cain
Keyword(s):  
Community Colleges ◽  
The Road ◽  
On The Road
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