Fine Particles Spreading Into the Roadside Model and Typical of its Distribution

Model of fine particles dispersion when crosswind is blowing is created on the ground of immediate observations of a whirl of dust formed behind a driven car. When the wind is absent, the cylindrical shape whirl of dust immediately changes into the cylindrical shape with a cut-off by the ground dust cloud. The properties of the distribution of particles concentrations model were studied on the basis of regression equation of probability density function. By variation of α0 , efforts were made to find the best congruence of normalised probability density and experimental data. For a practical implementation of the model it is important that the influence of the wind speed change in the distribution of the particles concentrations. A good congruence of regression equation and experimental data in the distances of more than 90 m from the road shows that, when the wind speed is low, the particles distribution scheme described in the model fits very well

Site Damage Tests of Geotextiles Used for Layer Separation in Road Construction

In recent decades Lithuania has witnessed an increase in road construction and reconstruction works involving the use of geosynthetics, which is usually concerned with special functions. One of them is separation of layers of aggregate by geotextile in the structure of road pavement. To successfully implement the separation, there are several crucial factors to be taken into consideration: the integrity, durability of the material and damages identified during installation. In Lithuania the geosynthetics is selected on the basis of eight-year-old interim guidelines and recommendations of suppliers. The paper deals with the systems of selecting geosynthetics in Lithuania and other countries. Then the results of experimental research are assessed. The present research has selected 5 types of geosynthetics of some manufacturers. The geotextiles were installed between different layers of road pavement structure. The analysis focuses on geotextile damages emerging during installation and their impact on performing the function of separation

Condition Monitoring of Bituminous Pavements Subjected to Repeated Dynamic Aircraft Loading

The Heavy Weight Deflectometer (HWD) is one of the most commonly used devices for monitoring the structural condition of airport pavement infrastructure systems on a routine basis in a rapid and non-destructive manner. The HWD measures pavement surface response (ie deflections) to an applied dynamic load that simulates a moving wheel of an aircraft at moderate speeds. The pavement surface deflection basins obtained by the HWD tests is frequently used as an indicator of the load-bearing capacity of the pavement. These tests were conducted on flexible test pavements at the US Federal Aviation Administration’s National Airport Pavement Test Facility (NAPTF) at various times to monitor the effect of simulated Boeing 777 and Boeing 747 aircraft gear trafficking on pavement structural condition. Multi-Depth Deflectometers (MDDs) installed within the pavement sections recorded the load-induced displacements in the pavement and in the subgrade. In this paper, the variations in HWD surface deflections acquired at different stages of NAPTF trafficking are compared with the MDD resilient displacements obtained under multiple-wheel heavy aircraft gear trafficking as well as with the periodic rut depth measurements. The results demonstrate the usefulness of routinely collected HWD surface deflection basins for reliable evaluating the structural performance of airport flexible pavements

Improvement of Road Traffic Safety on the Basis of Forecasting a Potential Danger in Places of Conflict Situations

The paper gives the results of perfecting of the method for forecasting accident rate susceptibility on the controlled crossroads of potential danger. The program allowing to reduce the labour expenditures in forecasting the accident rate probability is developed. Some recommendations for reducing the accident rate probability are worked out. Also recommendations for the road traffic safety improvement at the conflict objects (pedestrian crossings and crossroads) are given. Measures aimed to the improvement of traffic safety at the controlled crossroads are singled out

Assessment of Pavement Structural Strength by the Falling Weight Deflectometer

The main objective of the research project was to derive the equation for calculating the pavement equivalent E-modulus on the basis of the Falling Weight Deflectometer (FWD) deflection measurement data to be used in the Estonian Pavement Management System (EPMS) for network and project level analysis so, that the determined values are comparable with the Estonian flexible pavement design procedure 2001-52. In 1999, 32 and in 2001 additional 19 FWD test sites were chosen on actual pavement structures to perform FWD measurements annually, once or twice per month from early spring until late autumn. FWD measurement data were analysed mathematically and the results were compared with the Estonian flexible pavement design procedure. The research project results in the following:The quantitative methodology for evaluating the qualitative characteristics of the pavement is determined on the basis of the Cobb-Douglas equation, taking into account at a time practically an unlimited number of factors influencing the pavement structural condition.The relationship between the pavement equivalent elastic modulus calculated according to the Estonian flexible pavement design procedure 2001-52 and based on the FWD measured deflection is determined. The equation for calculating of the pavement equivalent E-modulus on the basis of the FWD deflection data to be used in the EPMS is derived.The correction factors for the pavement equivalent E-modulus, taking into account the month of the FWD measurement performance, moisture conditions and road embankment height at the FWD test site, are mathematically based on statistical data determined for Estonian conditions

Discrete Analysis Method for Suspension Bridges

In the calculation of suspension bridges, the geometrically non-linear behaviour of the parabolic cable is the main problem. The linear methods of analysis suit only for small spans. A geometrically non-linear continual model is especially useful for classical loading cases - a uniformly distributed load on the whole or a half span. But the modern traffic models consist of concentrated and uniformly distributed loads. The discrete model of a suspension bridge allows us to apply all kinds of loads, such as distributed or concentrated ones. The simplest suspension bridge consists of a geometrically non- linear cable, connected by hangers with an elastic linear stiffening girder. Depending on the load case, the hangers may be unequally loaded; thus the cable may also be loaded by unequal concentrated forces. The assumptions of the discrete method described here are: linear elastic strain-stress dependence on the material and absence of horizontal displacements of hangers. Hangers elongation is taken into account. Some comparative numerical examples are presented

Deterioration of Bridge Deck Roadway Members. Part I: Site Investigations

Bridge deck ancillary components such as surfacing, waterproofing, expansion joints, safety barriers, and drainage are important elements of highway bridges. These elements have an influence on either traffic safety and comfortability or the behaviour of the superstructures and substructures of a bridge. When they fail to function properly, the performance of bridges can be seriously affected. In this article deterioration and damages of deck components in highway bridges are analysed. The extent, causes and consequences of deterioration problems were investigated. A database analysis of field inspection results was performed. An investigation revealed that roadway members inevitably deteriorate over time at different rates. Illustrative examples of deteriorated roadway members are presented. The experience shows that lifetime of certain components is only about 5 to 7 years, sometimes less