Investigation of asphalt texture roughness on friction evolution for wheeled vehicles

Novelty of the research lies in understanding the safety advantages of asphalt made using advanced pavement design process – compact asphalt pavement installation. Variation of tyre–road friction coefficient for this type of pavement design is new and little-studied phenomenon. The present study focuses on the research into tyre–pavement interaction on dry asphalt pavement surfaces to quantify the effect of microprofile on vehicle performance in establishing its braking conditions. The data on a number of different indications (vehicle speed, adhesion coefficients calculated on the basis of braking and friction forces, maximum adhesion coefficient mmax and its ‘minimum’ value m100%) and measurement results generated using SRT-4 device for investigation of two road stretches at intervals of 100 m are presented in this paper. The interdependence analysis of statistical variables mmax and m100% has also been presented to exhibit the use of the method. Following statistical parameters are taken into account during random value analysis in order to assess the homogeneity of data: average value, dispersion, standard deviation, confidence interval around a sample mean, and correlation function. Finally, we provide a map between the adhesion coefficient and the longitudinal slip rate for stable and unstable braking conditions of a vehicle

Determination of seasonal factors for structural condition values of bituminous pavements

This article studies the effect of each season on the structural condition values of bituminous pavements. Testing of bituminous pavements was carried out by the falling-weight deflectometer DYNATEST 8000. FWD. The following values of pavement strength were used: the equivalent resilient modulus of the road pavement Eekv; deformation modulus of the roadbed soil Eg; pavement structural number SN; subgrade structural number SNSG; a modified structural number SNC. In the process of work the structural condition values of spring and autumn were determined and a statistical analysis of these values was presented. The analysis of the three-year research results showed that in spring the pavement condition weakens in respect of all criteria of pavement structural condition. Therefore, for the future analysis only the structural condition values of spring are suggested to be used. The article gives also the critical period adjustment factors for each structural condition value on the selected test road sections with different pavement structure. The article gives recommendations for the practical use of research results. Frist Published Online: 30 Jul 201

Investigation of Occupant Fatalities and Injuries During the Impact of Vehicle and Road Safety Barrier

The main purpose of any road restraint system is saving human life and minimizing injuries. The efficiency of road restraint system is its capability to hold vehicle on the road, to decrease occupant injuries and damage to the impacted objects. The road restraint systems currently used in Lithuania meet the European Standard EN 1317. Acceleration Severity Index (ASI) and Theoretical Head Impact Velocity (THIV) are derivative values used in this standard mainly to describe simulation of vehicle and safety barrier impact situations and to study vehicle crash dynamics. This paper presents simulation of different situations of vehicle and road restraint system crash. Computer impact simulation analysis was performed as well as comparable investigation of conventional injury criterions Head Impact Criteria (HIC) and those used in the European Standard EN 1317

Traffic Management Solutions at Roadwork Zones During Planned Special Events

Planned special events (PSEs) attract more people than usual to specific areas, which leads to increased traffic flows and congestions on the roads. Roadwork zones are among the most vulnerable areas on the roads, where increased traffic can lead to congestion. In roadwork zones, the vehicle flow capacity is already lower than in the conventional situations without roadworks, but at the time of PSEs, these zones become difficult to pass if no attention is paid to the change of the traffic management scheme. This kind of events poses many threats for road authorities, thus, new traffic management systems should be considered. This paper analyzes 2 PSEs and one national celebration in Lithuania and a significant impact they have on the regular traffic flow. PSEs are taken into consideration as they attract traffic to a known place; however, national celebrations distort traffic along all roads and it is not known exactly, which roads will be congested the most. Since roadwork zones cause congestion problems even in conventional situations, this paper presents traffic capacity calculations at these road stretches during PSEs and considers how they change depending on the traffic management scheme

Research of congestions in urban transport network using cellular automation model / Spūsčių miesto transporto tinkle tyrimas, taikant ląstelinio automato modelį / Исследование перегрузки городской транспортной сети с применением модели клеточного автомат

The growing demand for transport and communication services leads to more and more important, traffic related and closely associated problems, especially in the city centre, such as traffic congestion, air pollution, noise and some others. When modelling traffic flows in the Kaunas city centre, the simulation models of crossroads were created based on the principle of cellular automaton model, taking into consideration such relevant traffic indicators as the average speed of traffic flow in different streets, traffic intensity, congestions and distributed flows. Operation of cellular automaton model is associated with the improved approach of further vehicle model. Modelling of microscopic traffic flows is based on the brake light–cellular automaton (BL–CA) model. Random functions were made discreet and autocorrelation values of these functions were calculated in this work. Fundamental macroscopic traffic characteristics were obtained. Numerical dependences of the average traffic speed and traffic flow, traffic density and traffic flow, the average traffic speed and density were determined, with a help of which the demand parameters of transport network were evaluated in the Kaunas city centre in certain time intervals. Santrauka Didėjantis susisiekimo poreikis lemia vis aktualesnes, ypač centrinėse miestų dalyse, tarpusavyje glaudžiai susijusias eismo problemas: eismo spūstys, oro tarša, triukšmas ir kt. Darbe atliekant transporto srautų Kauno miesto centre modeliavimą, sudaryti ląstelinio automato modelio principu veikiantys imitaciniai sankryžų modeliai, įvertinant tokius eismo požiūriu aktualius rodiklius kaip vidutiniai eismo srauto greičiai skirtingose gatvėse, eismo intensyvumas, eismo spūstis ir srautų pasiskirstymas. Ląstelinio automato modelio veikimas susietas su patobulintu tolesnio automobilio modelio priartėjimu. Mikroskopinis eismo srautų modeliavimas paremtas ląstelinio automato (brake-light, BL-CA) modeliu. Darbe diskretizuotos atsitiktinės funkcijos, apskaičiuotos šiųfunkcijų autokoreliacinės reikšmės. Gautos fundamentalios makroskopinės transporto eismo charakteristikos. Nustatytos vidutinio eismo srauto greičio ir eismo srauto, eismo tankio ir eismo srauto, vidutinio eismo srauto greičio ir tankio skaitinės priklausomybės, kuriomis remiantis įvertinti transporto tinklo paklausos parametrai Kauno miesto centre tam tikrais laiko intervalais. Резюме Возрастающая потребность в перемещении приводит к тесно взаимосвязанным проблемам движения: перегрузке движения (заторам), шуму, загрязнению среды и т. д., что проявляется и особенно актуально в центральных частях города. В статье исследуются транспортные потоки в центре города Каунаса (Литва). С использованием принципа модели клеточного автомата (клеточный автомат – это математический объект с дискретными пространством и временем, каждое положение в пространстве представлено отдельной клеткой) созданы действующие имитационные модели перекрестков, учитывающие актуальные с точки зрения движения показатели: среднюю скорость потока движения на различных улицах, интенсивность движения, перегрузку потока и распределенный поток. Работа модели клеточного автомата связана с усовершенствованной моделью приближения следующего автомобиля. Микроскопическое моделирование потоков движения основано на модели клеточного автомата (brake-light, BL-CA). В работе дискретизированы случайные функции, вычислены значения автокорреляции этих функций, получены фундаментальные макроскопические характеристики транспортного движения, установлены числовые зависимости средней скорости потока движения и потока движения, транспортной плотности и потока движения, средней скорости движения и плотности, с помощью которых оценены параметры потребности транспортной сети в центре Каунаса с определенными временными интервалами. Reikšminiai žodžiai: eismo spūstis, transporto tinklas, srauto greitis ir intensyvumas, ląstelinio automato modelis Ключевые слова: перегрузка движения, транспортная сеть, скорость, интенсивность потока, модель клеточного автомат

Improvement of Road Pavement Maintenance Models and Technologies

The roads as main national assets maintenance costs increase dramatically but budgets stays as it is or even decrease over the years. However, at the same time, it is required to maintain road pavements condition at high level. These trends make asset owners and administrators to search for new ways and methods for more efficient roads maintenance management. As the new road is build or old one reconstructed performance indicators should be identified for whole life cycle as it is defined by design. Pavement condition evaluation by indicating present performance indicators level should be done timely and accurate at road level and whole network level. Ongoing support of pavement condition under network level, with a long-term strategy, allows to prolong the life of the pavement, improve traffic safety and meet public expectations. The comprehensive analysis of road maintenance and management systems recommendations for their improvement and application are presented in the article

Elastic Foundation Displacement Approximations

Interaction of an elastic foundation and structures like beams, plates and frames plays an essential role in investigating soil media in contact and impact mechanics. The solution to this interaction problem is complicated even the foundation is assumed as a linear elastic medium. E. Winkler suggested the fair representation of the foundation in 1867, and then, to bring it closer to reality, an interaction between the spring elements was introduced. In this paper, a relatively simple membrane-spring system is investigated, where an ideal gas is added under or above the membrane. In many cases, this constant pressure in the cavity modifies the solution and accuracy of the approximation is significantly increased. The cases of concentrated normal force and uniform distributed load are examined. The results of elastic half-space line displacements and the membrane displacements are presented

Dygliuotų padangų poveikio kelio dangai ir aplinkai analizė bei vertinimas (I dalis)

In order to determine the effect of studded tyres on road traffic safety, this article, based on Lithuanian and foreign countries researches, gives an overview of the performance of winter tyres, influence of the type of tyres on fuel consumption. Also, it presents the dependency of accident risk on road pavement condition, studies the effect of studded tyres on road pavement and pavement marking, gives an analysis of traffic accidents on Lithuanian roads and streets in different aspects.Lietuviška santrauka. Siekiant įvertinti dygliuotų padangų įtaką saugiam eismui, straipsnyje, remiantis Lietuvoje ir užsienio šalyse atliktais tyrimais, apžvelgtos žieminių padangų darbo charakteristikos, padangų tipo įtaka kuro sąnaudoms. Taip pat pateikta eismo įvykių rizikos priklausomybė nuo kelio dangos būklės, išnagrinėtas dygliuotų padangų poveikis kelio dangai bei kelio ženklinimui. Šiame darbe atlikta eismo įvykių Lietuvos automobilių keliuose ir gatvėse analizė įvairiais aspektais

Analysis and Evaluation of the Effect of Studded Tyres on Road Pavement and Environment (I)

In order to determine the effect of studded tyres on road traffic safety, this article, based on Lithuanian and foreign countries researches, gives an overview of the performance of winter tyres, influence of the type of tyres on fuel consumption. Also, it presents the dependency of accident risk on road pavement condition, studies the effect of studded tyres on road pavement and pavement marking, gives an analysis of traffic accidents on Lithuanian roads and streets in different aspects