Sample records for aquaplanes
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Aquaplaning : Development of a Risk Pond Model from Road Surface Measurements
Nygårdhs, Sara
2003-01-01
Aquaplaning accidents are relatively rare, but could have fatal effects. The task of this master’s thesis is to use data from the Laser Road Surface Tester to detect road sections with risk of aquaplaning. A three-dimensional model based on data from road surface measurements is created using MATLAB (version 6.1). From this general geometrical model of the road, a pond model is produced from which the theoretical risk ponds are detected. A risk pond indication table is fur-ther created. The...
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Highway Design on the Sections Affected by Aquaplaning
Directory of Open Access Journals (Sweden)
Aleksandr Reznik
2011-04-01
Full Text Available Pouring rain, snow melting, water condensing, fog and other natural phenomena cause the collection of water on roadway pavement, leading to the decrease of road-holding capacity of a tyre.When a car or a light truck is moving at a high speed on wet road pavement, the water under its wheels cannot be expelled in time.It results in raising of the front wheels of the vehicle above the road surface under the action of a hydrodynamic force and loss of vehicle control.The methods ensuring traffic safety on road sections, where vehicle’s aquaplaning is possible, should be developed by identifying and improving these sections at the stages of highway design, reconstruction and maintenance and by limiting traffic speed of vehicles.Keywords: vehicle, road, road-holding capacity, aquaplaning, reconstruction, maintenance, traffic safety.DOI: 10.3846/mla.2009.6.06
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Niskanen, Arto J.; Tuononen, Ari J.
2014-05-01
The tyre-road contact area was studied visually by means of a high-speed camera and three accelerometers fixed to the inner liner of the tyre carcass. Both methods show a distorted contact area in wet conditions, but interesting differences appeared. First, the contact area in full aquaplaning seems strongly distorted on a glass plate when subjected to visual inspection, while the accelerometers indicate a more even hydrodynamic aquaplaning contact length (CL) across the tyre width. Secondly, the acceleration sensors predict the clear shortening of the CL of the tyre before the critical aquaplaning speed. It can be concluded that the visual contact area and shape are heavily dependent on the transparency of the liquid and smoothness of the glass. Meanwhile, the tyre sensors can provide a CL estimate on any road surface imaginable.
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Energy Technology Data Exchange (ETDEWEB)
Hernandez Orue, J.M. [Servicio de Aguas Diputacion Foral de Alava, Vitoria (Spain); Nieves de la Vega Sedo, G.
1996-08-01
Requirements of wastewater discharges, in order to maintain and improve receiving water qualities, create a demand of means of wastewater management besides implementation of control systems, technical and economical management programs and financing. In this background, Direccion de Medio Ambiente of Diputacion Foral de Alava, through its Water Service, has settled the need of a integral planning for wastewater management in Rioja Alavesa. This job has been commanded to the engineering consulting AQUA/PLAN, S.A. (Author)
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Time resolved analysis of water drainage in porous asphalt concrete using neutron radiography.
Poulikakos, L D; Sedighi Gilani, M; Derome, D; Jerjen, I; Vontobel, P
2013-07-01
Porous asphalt as a road surface layer controls aquaplaning as rain water can drain through its highly porous structure. The process of water drainage through this permeable layer is studied using neutron radiography. Time-resolved water configuration and distribution within the porous structure are reported. It is shown that radiography depicts the process of liquid water transport within the complex geometry of porous asphalt, capturing water films, filled dead end pores and water islands. Copyright © 2013 Elsevier Ltd. All rights reserved.
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Tyre contact length on dry and wet road surfaces measured by three-axial accelerometer
Matilainen, Mika; Tuononen, Ari
2015-02-01
We determined the tyre contact length on dry and wet roads by measuring the accelerations of the inner liner with a three-axial accelerometer. The influence of the tyre pressure, driving velocity, and tread depth on the contact length was studied in both types of road surface conditions. On dry asphalt the contact length was almost constant, regardless of the driving velocity. On wet asphalt the presence of water could be detected even at low driving velocities (e.g. 20 km/h for a worn tyre) as the contact length began to decrease from that found in the dry asphalt situation. In addition to improving the performance of active safety systems and driver warning systems, the contact length information could be beneficial for classifying and studying the aquaplaning behaviour of tyres.
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Aspects of Applying Weather Radar Based Nowcast for Highways in Denmark
DEFF Research Database (Denmark)
Rasmussen, Michael R.; Quist, MIchael; Thorndahl, Søren Liedtke
nowcast can be used for two scenarios: 1) Safety - reduced visibility and possibility for aquaplaning can jeopardise the safety of the road users 2) Construction and maintenance - ensuring protection against flooding and pollution. The two different applications can represent two different precipitation......The Danish road network consists of 73.331 km. of roads. 3.790 km. of these roads are state roads and are considered as major lines of transportation. Although these roads only represent 5% of the total network, 45% of all traffic is moving along these roads. Application of weather radar based...... on the visibility, rain intensity and rain volume. This can actively be used to optimise basin volumes and to direct critical information to traffic. A system for nowcast dedicated to road applications are under development in Denmark. This paper investigates the different approaches in nowcasting of precipitation...
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With a flick of the lid: a novel trapping mechanism in Nepenthes gracilis pitcher plants.
Directory of Open Access Journals (Sweden)
Ulrike Bauer
Full Text Available Carnivorous pitcher plants capture prey with modified leaves (pitchers, using diverse mechanisms such as 'insect aquaplaning' on the wet pitcher rim, slippery wax crystals on the inner pitcher wall, and viscoelastic retentive fluids. Here we describe a new trapping mechanism for Nepenthes gracilis which has evolved a unique, semi-slippery wax crystal surface on the underside of the pitcher lid and utilises the impact of rain drops to 'flick' insects into the trap. Depending on the experimental conditions (simulated 'rain', wet after 'rain', or dry, insects were captured mainly by the lid, the peristome, or the inner pitcher wall, respectively. The application of an anti-slip coating to the lower lid surface reduced prey capture in the field. Compared to sympatric N. rafflesiana, N. gracilis pitchers secreted more nectar under the lid and less on the peristome, thereby directing prey mainly towards the lid. The direct contribution to prey capture represents a novel function of the pitcher lid.
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Bauer, Ulrike; Bohn, Holger F; Federle, Walter
2008-02-07
The leaves of Nepenthes pitcher plants are specialized pitfall traps which capture and digest arthropod prey. In many species, insects become trapped by 'aquaplaning' on the wet pitcher rim (peristome). Here we investigate the ecological implications of this capture mechanism in Nepenthes rafflesiana var. typica. We combine meteorological data and continuous field measurements of peristome wetness using electrical conductance with experimental assessments of the pitchers' capture efficiency. Our results demonstrate that pitchers can be highly effective traps with capture rates as high as 80% but completely ineffective at other times. These dramatic changes are due to the wetting condition of the peristome. Variation of peristome wetness and capture efficiency was perfectly synchronous, and caused by rain, condensation and nectar secreted from peristome nectaries. The presence of nectar on the peristome increased surface wetness mainly indirectly by its hygroscopic properties. Experiments confirmed that pitchers with removed peristome nectaries remained generally drier and captured prey less efficiently than untreated controls. This role of nectar in prey capture represents a novel function of plant nectar. We propose that the intermittent and unpredictable activation of Nepenthes pitcher traps facilitates ant recruitment and constitutes a strategy to maximize prey capture.
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Energy Technology Data Exchange (ETDEWEB)
Trabelsi, A.
2005-07-01
In this work methodical approaches to predict the friction value as a driver warning information or as a preconditioning of vehicle control systems are presented. The focus of this work is the description and classification of the road state with the help of a multi sensor concept. Additionally to the use of standard vehicle sensors different additional optical and acoustic sensors have been analysed. These sensors allow an automatic detection of the road state before critical driving situations are reached and give a help for the driver to guess the actual friction state. The use of information about the road brightness and brilliance leads to the detection of the inter-medium on the road. This can be supported by a model-based correction of the influence of the sensor height. The tire-road noise can also be used to describe the road state and detect water and show on the road. An appropriate image processing algorithm leads to the detection of road wetness and lane grooves from a cut out of images of a lane keeping camera. Furthermore the examination of the road texture with the help of a laser profilometer helps getting a better understanding of the contact problems between tyre and road. A 3-dimensional presentation of the road roughness can be connected to a 3D-contact model to describe the contact surface and the force partition in the foot print. In addition, the approach of a model-based detection of slippery road conditions mainly with the help of ESP sensors will be presented. This model is based on the calculation of the form slip part with a statically approximated multi-field and the sequentially detected sliding slip on low-{mu} road surfaces. With this approach it is possible to detect slippery wet roads, aquaplaning situations, ice and snow considering the application conditions. The connection of the different sensor data follows in a road state estimation block with an extended Sugeno-Fuzzy expert system. By the definition of a 3-stage signal