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Finite element modelling of flexible pavement reinforced with geogrid
Published in Gianluca Dell’Acqua, Fred Wegman, Transport Infrastructure and Systems, 2017
Rutting is a serious issue for road users for two reasons: driving in the rut is difficult and the water collecting in these depressions cannot drain freely off the pavement surface and may cause aquaplaning, making rutting a potential safety hazard. Rutting in flexible pavement develops gradually with increasing numbers of load applications, usually appearing as longitudinal depressions in the wheel paths accompanied by small upheavals to the sides. In addition, as a consequence of the increased tire pressure and axle load, the surfacing asphalt layer is subjected to increased stresses, which result in permanent (irrecoverable) deformations. The permanent deformation accumulates with increasing number of load applications. The permanent deformation in the surface layer, thus, accounts for a major portion of rutting on flexible pavements subjected to heavy axial loads and high tire pressures.
Tyres, road wheels and hubs
Published in M.J. Nunney, Light and Heavy Vehicle Technology, 2007
A flooded as opposed to a wetted road surface poses a much more serious threat to tyre adhesion. It is then possible for the combined effects of speed and depth of water to be such that a worn tyre is no longer able to remove quickly enough the water from its contact area with the road especially if the remaining depth of tread pattern is approaching the legal limit stated in the next section. In this event, the tyre can become entirely supported by the film of water with consequent loss of control. This condition is known as aquaplaning or dynamic hydroplaning, since a water wedge builds up between the tyre and road to generate a hydrodynamic upthrust on the tyre (Figure 22.12). Indeed the action can be likened to that of hydrodynamic lubrication of a plain bearing, as described in Section 4.2.
Climate as a factor in the planning and design of new roads and motorways
Published in A.H. Perry, L.J. Symons, Highway Meteorology, 1991
The principal problems of rainfall for road traffic are poor visibility, loss of skidding resistance (aquaplaning) and, to a lesser extent, reflections from a wet road surface at night. Where the road is exposed to strong winds, the problems of driving rain make the situation worse. Spray, which is often dirty, thrown up by passing vehicles will cause visibility conditions to deteriorate, particularly in darkness. A very important consideration for drivers of scooters and motorcycles in rain is that they have no facility for wiping water droplets off their windshields or the visors of their helmets; with reflections from surface water on the road frequently obscuring road markings, this can be a potentially dangerous situation, especially for the inexperienced.
Implementation of polymer optical fibre sensor system for monitoring water membrane thickness on pavement surface
Published in International Journal of Pavement Engineering, 2021
Yanqiu Bi, Jianzhong Pei, Fucheng Guo, Rui Li, Jiupeng Zhang, Ning Shi
Measuring water membrane thickness on the surface of pavement during intense rainfall events is necessary for ensuring vehicle safety and managing urban drainage (Gallaway et al.1900, Russam and Ross 1968). The anti-skid performance on a wet pavement is markedly lower than that on a dry surface. If the water membrane thickness increases beyond the critical point at which the tire can disperse it, the water membrane in front of the tire will accumulate, resulting in a reduction of the contact area between the tires and the pavement. If the tire completely loses contact with the pavement, a condition known as aquaplaning will occur (Mancosu et al.2000). Therefore, accurate information of road water membrane thickness is necessary to ensure vehicle safety. Commonly used water level measuring equipment includes the float-type water level gauge, bubble-type water level gauge, the ultrasonic water level gauge, the radar water level gauge, the laser water level gauge, and the electronic water gauge (Mezikov et al.1991, 1993). However, these equipment show some limitations such as their expensive price and lower precision; thus, they cannot be used to monitor water membrane thickness on the pavement surface. Therefore, innovative, precise, inexpensive, and feasible techniques are required to monitor the water membrane thickness of the road surface. The application of sensors is a critical component of smart roads, and it is also one of the hotspots of current road engineering research.