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Business environment is full of ups and down and this makes companies to develop different ways of using resources. By expanding life cycle of products, these ways can be cost effective and not harmful for environment. As Reverse Logistics (RL) uses a product after end of its life, it reduces pollution, therefore it has been considered as a part of sustainable development. The core goal of current research is developing a framework by which it evaluates Third Party RL Provider (3rdPRLP) using Multi-Criteria Decision-Making (MCDM) based on Fuzzy Additive Ratio ASsessment (FARAS). Thirty-seven criteria were identified, which are classified into seven main criteria. The main criteria were ranked as follows: product lifecycle position C1, RL process function C2, organizational performance C3, organizational role of RL C4, IT system and communication C5, general company consideration C6, geographical location C7. Market coverage, destination, financial considerations, integrated system, reclaim, efficiency and quality, and growth are each group’s dominant sub-criteria. In addition, the current research helps the logistics managers to better understand the key attributes’ complex relationships in the environment of decision-making. First published online 21 January 2021

Recycled hot-mix asphalt (RHMA) mixture is produced from reclaimed asphalt pavement (RAP) by adding an appropriate amount of new mineral materials improving the gradation of RHMA, a lower viscosity bituminous binder and a rejuvenator. The manufactured RHMA mixture must meet the same technical requirements as those for the hot-mix asphalt (HMA) mixture made of new materials only. It is also aimed at reducing its cost to the minimum in order to comply with technical requirements for the RHMA mixture in the asphalt mixing plant (AMP). These goals are ensured in the process of determining the composition of the RHMA mixture applying numerical and experimental methods for selecting an optimal content of old and new materials in the mixture. The article presents a method for determining the composition of the RHMA mixture, which allows calculating the maximum allowable percentage of RAP depending on its homogeneity. Setting the established maximum RAP amount as a constant size, the required content of new mineral materials is estimated thus taking into account bitumen capacities. The price of a single ton of the materials making the RHMA mixture and information on technical requirements for the composition of the RHMA mixture assist in applying certain technological restrictions, which makes it possible to calculate an optimal content of the components. The research findings obtained from the representative sample demonstrated that ready-for-use RAP was not homogeneous, and its five properties used for calculating its maximum allowable amount had different variations. The paper presents the algorithms that are actualized using mathematical programming methods upon the application of which the following objectives were solved: the assessment of technological requirements helped to obtain the RHMA mixtures of the cheapest or densest mineral part, and the mixture having the lowest content of bitumen was received. The article discusses mathematical analogues that can be used for determining whether the RHMA of the right gradation can be produced from the available mineral materials and allows analysing the mixtures that do not meet the established requirements thus identifying the causes of inappropriateness. The introduced algorithms can be applied at the initial stage of designing the RHMA mixture thus reducing the duration and cost of the design process. In order to determine whether the calculated content of old and new materials is appropriate, the standard specimens produced and examined in the laboratory need to be confirmed.

European Union members seek to establish the principles of a circular economy, which is based on the efficient use of raw materials and resources. This requirement will have an impact on business and in particular on the road construction sector. Hence the need to improve the asphalt mixing plant (AMP) mixing technology utilizing as much as possible reclaimed asphalt pavement (RAP) to produce asphalt mixtures (AM) for road construction. The resources used to produce new AM in the world are endless and becoming more expensive in a time scale. The multi-cycle reuse of RAP producing AM is a priority, when thinking about of economical recycling materials usage and the saving of resources. The design and development of RAP hot recycling in-plant technologies has been in progress for approximately half a century. In high-level-economy countries, AM production currently processes on average approx. 80% of the amount of RAP using innovative techniques on AMPs. Design of various AMP, their assessment on the flexible application of innovative techniques depending on the RAP processing method, are described in this paper. In this paper different recycling technologies in AMP and their advantages and disadvantages are reviewed. The research result indicates technical possibilities hot recycling in-plant in Baltic countries. Local authorities, research institutes, road construction and road design companies could use these results in the future. DOI: https://doi.org/10.3846/enviro.2020.632

This article presents results of the modelling of temperature regimes of railway construction layers in application of the SV HEAT software. In one case, ambient air temperature affects the railway construction in presence of a snow cover and in another case – without it. Temperature changes in railway construction layers were modelled pursuant to the data of the Lithuanian Hydrometeorological Service of January–February 2015 in Vilnius region and the conducted field experimental studies. Ambient air temperature, moisture content in layers and snow cover thickness were assessed. Properties of the materials used to install railway construction layers were identified in the laboratory. Moisture content and temperature in construction layers were measured using sensors installed in the experimental field stand (DRETM II) set up in Slovakia. Modelling results have shown that the greatest temperature difference with a snow cover layer on the top railway construction and without it is 1.2 °C. These data revealed that a snow cover carried out the function of a thermal insulation layer. The railway construction with a snow cover had a lower freezing depth (difference of 0.5 cm). With increasing distance from the top of the ballast layer, the temperature of construction layers with a snow cover approaches the temperature of the construction without a snow cover, i.e. temperatures tend to approximate.

Magic Formula (MF) tyre model is widely used for the analysis of tyre behavior in different driving situations. The model is mostly used to fit the simulation and experimental data slip curves. As there are many modifications of the MF, this paper presents a literature analysis of MF application and fitting techniques. A short review of other empirical tyre models was also made. At the end, a simple least squares minimisation technique was used to fit the experimental data of longitudinal tyre performance on ice. Measurements were performed with the inner drum test rig in the laboratory. In general, the fitting showed a very good accuracy.

The last important production step in hot-mix asphalt aggregates production is a final screening (classifying) of secondary or tertiary crushed materials, which has to ensure high quality screening curves of end-products in accordance with standards and this process should run in most valuable economic way. The data of the screening machines from different 5 top manufacturers in same machine class were analysed in accordance with output, screening efficiency and owning and operation costs. This paper demonstrates to quarry managers possible correct choose of mobile screens, which ensure high production outputs and quality requirements and saves operation costs.

The use of high quality aggregate mixture, proper technological parameters of laying and compacting as well as the required thickness of the mixture ensures railway sub-ballast layer properties. In this paper gradation, den­sity and water permeability of 49 produced random samples of aggregate sub-ballast (ASB) mixture which were taken from the stockpile in the plant and from the uncompacted railway layer are investigated. The statistical parameters of the ASB mixture quality indicators and histograms with theoretical curves of normal distribution are presented as well. Their conformity to normal distribution was tested through the use of skewness, kurtosis, Pearson, Shapiro-Wilk and Kolmogorov-Smirnov methods. Regression analysis was employed to determine the dependence of standard deviation of percent passing on the mean percent passing through the sieves. In this paper a new method of determining the homo­geneity of ASB according to the variation of gradation using the maximum standard deviation value of this dependence was employed. The minimum size n was calculated with the permissible relative error of 5%, 10%, 15% and 20%. The obtained research findings revealed that due to segregation processes the homogeneity of ASB mixture from the point of its production to application has decreased by about 38%. First published online: 20 Apr 2016

The main elements of urban transport infrastructure include: the street network with intersections, bridges, viaducts, flyovers, vehicular traffic tunnels. Unsignalized four-leg intersections and roundabouts is the largest “saturated transport flow” of the street network. Roundabouts which were designed as far back as 1970–1980 were well-functioning when the car ownership level was 180–200 veh/1000 inhabitants. Currently, when the level of car ownership comes to 520–560 veh/1000 inhabitants, unsignalized roundabouts operate in the “oversaturated flows” regime. The research results of the Vilnius Gediminas Technical University and other universities showed that when designing new or reconstructing existing intersections the indicators of territorial planning, transport planning, environmental protection, traffic safety should be considered. As a common indicator for assessing all other indicators a monetization (estimation in monetary terms) should be used. When preparing projects for intersection reconstruction it is recommended to apply a new method of intersection analysis and evaluation based on the principles of sustainable development of urban transport infrastructure.

In the National Communication Development of 2014–2022 Program and Guidelines of the Development of the Public Electric Vehicle Charging Infrastructure confirmed by the Government of the Republic of Lithuania, it is planned that, until the year of 2025, among newly registered vehicles, electric ones should make at least 10 %. Analysis of the trend of electric vehicles makes evident that the target does not have a real chance to be achieved without targeted efforts. In order to improve the infrastructure of electric vehicles in major cities and resorts of Lithuania, we have carried out a comparative analysis of public infrastructure for electric vehicles in 18 Lithuanian cities and resorts. For the quantitative analysis, we proposed eight criteria describing such an infrastructure. As perception of the infrastructure by owners of electric cars depends on complex factors, we used multiple criteria evaluation methods (MCDM) for evaluation of the current state of its development by four such methods: EDAS, SAW, TOPSIS, and PROMETHEE II. Based on the evaluation results, prominent and lagging factors were understood, and proposals for effective development of public infrastructure of electric vehicles were proposed for improvement of the infrastructure. Keywords: development; electric vehicle; public infrastructure; MCDM; EDAS; SAW; TOPSIS; PROMETHEE II; COIN; decision-making.

The risk of accident increases significantly when tire rolls on ice comparing to the dry surface. The vehicle tirebecomes the main component of force transmission to the road and necessity of investigating the tire behavior becomes of highimportance. This paper presents results of tire force transmission measurement with two different winter tires at the sameoperating conditions. Longitudinal and lateral force coefficient characteristics as the functions of slip ratio and slip angle arepresented and discussed. The results showed a different lateral and longitudinal performance because of different tread patternand rubber compound. DOI: https://doi.org/10.3846/enviro.2017.146

This paper presents a simple method to determine dynamic modulus master curve of asphalt layers by con­ducting Falling Weight Deflectometer (FWD) for use in mechanistic-empirical rehabilitation. Ten new and rehabilitated in-service asphalt pavements with different physical characteristics were selected in Khuzestan and Kerman provinces in south of Iran. FWD testing was conducted on these pavements and core samples were taken. Witczak prediction model was used to predict dynamic modulus master curves from mix volumetric properties as well as the bitumen viscosity characteristics. Adjustments were made using FWD results and the in-situ dynamic modulus master curves were ob­tained. In order to evaluate the efficiency of the proposed method, the results were compared with those obtained by us­ing the developed procedure of the state-of-the-practice, Mechanistic-Empirical Pavement Design Guide (MEPDG). Re­sults showed the proposed method has several advantages over MEPDG including: (1) simplicity in directly constructing in-situ dynamic modulus master curve; (2) developing in-situ master curve in the same trend with the main predicted one; (3) covering the large differences between in-situ and predicted master curve in high frequencies; and (4) the value obtained for the in-situ dynamic modulus is the same as the value measured by the FWD for a corresponding frequency.

Due to destructive factors (traffic loads, climatic and weather conditions, improper exploitation materials), bitumen properties irreversibly change in unserviceable asphalt concrete. Due to irreversible processes of oxidation the aged bitumen stiffens, its physiochemical properties, ductility, adhesion and cohesion as well as sectional composition (relative amounts of asphaltenes, oils and resins) change. Bitumen in the reclaimed asphalt pavement (RAP) may be restored to properties approximate to those of the virgin bitumen by adding the following rejuvenators: softening or rejuvenating agents as well as soft bitumen. The article presents the experimental data on RAP obtained from laboratory tests conducted with Marshall specimens without additives when RAP was supplemented by different types of virgin road bitumen, the paving grade of which was 50/70, 70/100, 100/150, 160/220, respectively. The content of newly added binder of all types to RAP was 0.5%, 1.0%, 1.5%, 2.0%, and 50/70 in addition and 4.0% and 6.0% of RAP mass. The total bitumen content increased by the same percentage amount in the reclaimed asphalt, which was not always optimal. Marshall specimens were formed with these bitumen contents, the tests of which enabled to identify stability (S), flow (F), Marshall quotient (S/F), air voids content (Vm), bulk density (SDD – ρb SD) of asphalt concrete samples and the maximum density of asphalt. Having extracted all RAP and reclaimed asphalt samples according to the differential method, the factual content of soluble binder in them and its penetration, softening point, Fraass breaking point, ductility and penetration index Ip were calculated. The dependences of the reclaimed asphalt physical and mechanical parameters on the virgin rejuvenating bitumen grade and its added percentage amount were obtained. Data analysis and their generalization was conducted.

Road asphalt concrete pavement is usually laid of hot-mix asphalt (HMA) mixture. HMA mixture is produced in an asphalt mixing plant (AMP) according to the technology applied in its structure. AMP shall meet certain requirements set in the norms not only to the quality of HMA mix produced in it, but to environmental protection as well. A possibility to produce an HMA mixture of all required types and marks in it shall be available through the use of various materials and additives, including reclaimed asphalt pavement (RAP). HMA mixture production costs shall be as low as possible. AMP shall be of appropriate technical condition and with proper equipment, which mostly influence on the technological, ecological and economic parameters. Its actual productivity shall meet the required scope (HMA mixture amount) of road construction works carried out in the serviced region. The article presents 9 criteria of operating AMP quality, mathematical models of determining their significance through the application of an expert research method as well as expert opinion correlation values. Ranks of AMP quality criteria have been replaced by their weight indices through the application of two different methodologies. Quality criteria weight indices may be used according to an additive model through the calculation of operating AMP quality multi-criteria index. A numerical sample is presented at the end of the article.

The paper describes the essential differences in determining optimal gradation of hot mix asphalt (HMA) mixture used in road building at the stages of its selection, initial design and production, and presents the respective algorithms. The models of constrained and unconstrained non-linear optimization are developed, allowing us to choose the best HMA mixture gradation based on mineral materials, whose gradation is known, when the total percent passing of HMA mixture aggregates is considered to be equally important for all sieves, or when preference is given to some of the sieves. A new linear optimization problem best suited for practical use due to its simplicity is offered. By introducing weight coefficients for the dimensions of the objective function of the model, zero deviations of the percent passing of HMA mixture aggregates from their standard values may be easily obtained, based on the preferences set. All mineral materials (aggregates) obtained at batch-type asphalt mixing plants should be used for HMA production. Their total mass is equal to unity, while the mass of each material is a positive quantity, and a predetermined relationship between the masses of imported filler and the reclaimed dust is used. In the experimental part of the work, the problems were solved using the SAS system.

The weighted mass of a binder in the bucket of the bitumen batcher of a batch-type asphalt plant should be such that its percentage of hot mix asphalt (HMA) mixture lot would comply with the design amount of the job-mix formula in all mix batches. A bitumen batcher does not always weigh bitumen portions precisely. Their mass deviations from the amount determined by the project and its variation impair HMA composition and performance. The paper provides data on a statistical evaluation of bitumen batcher modernization performed at Lithuanian enterprise „LL“. The article analyzes differences in the structures of reconstructed and not reconstructed bitumen batching systems and presents methods for determining modernization effectiveness. The paper also focuses on the effectiveness of the batching system, determining deviations from bitumen content in subsamples taken and extracted everyday during two seasons (before and after batcher‘s modernization) of producing HMA from the value of job-mix formula and comparing them to the values of tolerances. Article in Lithuanian Modernizuotos bitumo dozavimo sistemos įtakos karštojo maišymo asfalto mišinio sudėčiai tyrimas Santrauka Asfaltbetonio maišytuvo (ABMA) bitumo dozavimo sistema (BDS) priskiriama sudėtingam vamzdynų transportui. Ji privalo ne tik laikyti reikiamos temperatūros bitumą, jį tiekti iš talpyklų į maišyklę, bet ir tiksliai dozuoti rišiklį leidžiant minimaliai pakisti jo savybėms. Periodinio veikimo asfaltbetonio maišytuve bitumo dozatoriaus bakelyje atsverto rišiklio masė turi būti tokia, kad jo procentinis kiekis karštojo maišymo asfalto (KMA) mišinio partijos visuose maišiniuose atitiktų projektinį kiekį, nustatytą darbinėje mišinio formulėje (DMF). Ne visada bitumo dozatorius tiksliai ir glaudžiai atsveria bitumo dozes, o tai blogina KMA mišinio sudėtį ir savybes. Pateikti Lietuvos „LL“ įmonės (pavadinimas pakeistas) BDS patobulinti statistinio vertinimo duomenys. Išanalizuoti nepatobulintos ir patobulintos BDS konstrukcijų skirtumai ir pateikta modernizavimo efektyvumo nustatymo metodika. BDS kokybė tirta per du KMA mišinio gamybos sezonus (prieš ir po modernizavimo). Kiekvieną dieną imtų ir ekstrahuotų tūrinių ėminių bitumo kiekių nuokrypių nuo DMF vertės lygintos su tolerancijų vertėmis. Reikšminiai žodžiai: karštojo maišymo asfalto (KMA) mišinys, asfaltbetonio maišytuvas (ABMA), bitumas, bitumo siurblys, svėrimo bakas, vamzdis, vamzdynų transporto sistema, bitumo dozavimo sistema (BDS), tikslumas, glaudumas, nuokrypiai, darbinė mišinio formulė (DMF).

Passengers’ transportation by rail involving various interested groups, such as managers, service staff and passengers, is a complicated process. Decision‐making persons, organizing railway trips should take into account the interests, needs and possibilities of these particular groups. The solution to some problems associated with passengers’ transportation by rail depends on the experience and qualification of decision‐makers, people who are responsible for the effectiveness of this work. To increase the quality of railway trips, the interested parties, groups of people mentioned above, should coordinate their actions, cooperate with each other in solving the problems and exchange relevant information. Therefore, the increasing quality of passenger transportation is a complicated issue, requiring good professional skills based on knowledge, practical experience, high intellect and new ideas of all the people involved in this process. The current paper presents a diagram showing passenger's transportation quality with a number of criterion groups A, B, C, D matching the structure and numbers of the questions included in the questionnaires to survey respondents (passengers) and experts (service and administration staff of the train). What is more, theAnalytic Hierarchy Process(AHP) methodology based on the pair wise comparison of criteria is used to determine their weights (significances) considering the data obtained from the respondents and experts of each of three categories. Only these questionnaires which have no contradictory estimates are used. Also, the calculation methods demonstrating the results of the survey are provided in this work. One more point such as the data elicited from the respondents who took part in the survey (i.e. passengers from the train running on the international route Vilnius‐Moscow) and experts (i.e. service staff of the already mentioned train and representatives of the administration staff from the Joint‐Stock Company ‘Lithuanian Railways’ (AB ,,Lietuvos geležinkeliai")) is analyzed. Finally, the conclusions for improving the quality for passenger transportation by Lithuanian railways are given. First published online: 10 Feb 2011

The aim of this work is to gather information about the national flexible pavement roads ruts depth, to determine its statistical dispersijon index and to determine their validity for needed requirements. Analysis of scientific works of ruts apearance in the asphalt and their influence for driving is presented in this work. Dynamical models of ruts in asphalt are presented in the work as well. Experimental outcome data of rut depth dispersijon in the national highway of Lithuania Vilnius – Kaunas is prepared. Conclusions are formulated and presented. Article in Lithuanian

The need for improving quality of passenger transportation by rail transport to increase the competitiveness of this means of transport is demonstrated. Major criteria influencing the quality of passenger transportation by rail transport are defined and expert evaluation questionnaires, allowing the authors to obtain the data on the presented criterion significance from the respondents (service people of the train) are prepared. The searching for ways of determining suitability of mathematical statistics methods for checking the concordance of expert judgements is described. For this purpose, the AHP (Analytic Hierarchy Process) method, allowing pairwise criteria evaluation, is used. Based on the calculated average values of the criterion significance and ranks, obtained using the data elicited from the questionnaires filled by the service staff of the trains (train masters, mechanic operators-electricians, conductors, etc.), the priority order of the criteria is determined. Article in Lithuanian

With a view to saving bitumen and mineral substances and also for the purpose of preventing environmental pollution, the old asphalt pavement (AP) may be milled without increasing the thickness of pavement structure and subjected to hot recycling for reuse in the same or any other location. However, the suitability of reclaimed asphalt pavement (RAP) for reuse depends on its composition (the content and gradation of bitumen) and the properties of its components. Hence, the present study aims at providing a systematic analysis of factors that determine the inhomogeneity of RAP. To this end, RAP samples, taken from RAP being loaded from the milling machine onto the transport means and from RAP stored in the territorial storage facilities of asphalt concrete (AC) plants, were examined in an accredited laboratory to determine, for each sample unit, the composition (the content and gradation of aged soluble bitumen), the content of moisture and the gradation of non-extracted granules. The statistical characteristics showing the actual homogeneity of RAP sampled from different sources were also estimated and analysed. Further, there was elaborated a model for comparing the homogeneity of RAP from different sample sets by the max values of standard deviations in the percentage mass passing the sieves and, based on the experimental data, derived the respective regression equation. The results of the performed comparison showed the absence of any statistically significant difference in terms of homogeneity between the three different RAP sample sets, i.e. RAP-1 sampled from the road, RAP-2 taken from the stockpiles being formed in different locations and RAP-3 obtained from RAP kept stockpiled in an open storage facility. The study was finalized by determining, in line with the Specification of Technical Requirements TRA ASFALTAS 08, the max content of RAP allowed for inclusion in a hot mix asphalt (HMA) mixture depending on the actual homogeneity of RAP determined.

The transportation of passengers by railroads is a dynamic process because setting, wherein the process takes place, undergoes continuous changes observed at technical, technological and transportation process planning levels. Every passenger has different needs and aims and can afford different possibilities. Therefore, the conception of quality differs in each individual case. In order to be able to plan a railway trip process in a proper manner, it is important to become familiarized with passenger needs and preferences and eliminate any existing deficiencies. To this end, it is reasonable to conduct passenger surveys. The paper provides an affinity diagram of railway transportation quality factors, the elements whereof correspond to the structure of the survey questionnaire. For determining the level of the quantitative significance (weight) of indicators, there was applied the method ofAnalytic Hierarchy Process(AHP) developed and introduced by the American scientist T. Saaty. The scope of research work carried out by the authors covered the determination of the highest eigenvalue, the compatibility ratio, the concordance correlation coefficient, the estimated and critical value ofchi‐squarevalues (the examples of estimations are presented in the paper) as well as the classification and processing of the surveyed data on passenger questionnaire and the analysis of respondents’ opinion. The closing part of the paper presents conclusions drawn based on the findings of the survey and respective recommendations for quality improvements in passenger transportation by Lithuanian railways. First published online: 27 Oct 2010

The aim of the study is to evaluate the influence of random errors of the stochastic technological process occurring in a batch type plant on the homogeneity of the hot-mix asphalt (HMA). The article presents the algorithm of prognosing mineral part composition of HMA, which takes into consideration a variation of mineral material cumulative percent passing through control sieves as well as errors of mineral material dose weight in the finite dosing. It is considered that percent passing and dose weight errors are independent random quantities, distributing according to the normal law. The original algorithm for the simulation of values of these two quantities is used. The mineral material grading and dose weight of the batches of HMA are selected through the use of the random number generator. To evaluate the homogeneity of the simulated lot of HMA batches, reference was made to Lithuanian Construction Recommendations R35-01, limiting the admissible deviations of components quantities of HMA in comparison with the job-mix formula. The example of simulation discussed above is presented, and the results are analysed.

It was determined that poor quality of asphalt concrete is the main cause (65 %) of early fatigue cracking of asphalt concrete pavement of roads in Lithuania and neighbouring countries with similar climatic conditions. The poor quality of asphalt concrete is mainly predetermined by production errors of hot mix asphalt (HMA) and designed suboptimal mass ratio of constituents. The development of theoretical principles for producing the best componential composition of asphalt concrete is highlighted. Optimal values of the portions of coarse aggregate, fine aggregate, filler and bitumen recommended by different authors are given. The main causes of deviations from the optimal composition of HMA produced by asphalt asphalt mix plants of different generations are systematised. The dynamics of rapid cracking of asphalt concrete paving of Lithuanian roads is shown emphasising the inadequacy of HMA structure and properties to increased traffic intensity and axial workloads. The permissible values of asphalt concrete components, optimal under the actual climate and traffic conditions, ensuring highest asphalt concrete resistance to fatigue and rational (8–9 years) service life, during which the cracked pavement area does not exceed 8 %, are proposed. A quality assurance method has been developed based on mathematical statistical methods. It helps avoid deviations of component proportions, occurring in the process of production, from the project proportion and to increase the homogeneity of the product.

Railway sub-ballast layer is a connecting layer between the ballast and other track layers. This layer must ensure even load distribution into the subgrade, drainage surface water, prevent materials of layers mixing. Ensuring these properties allows to extend the explotation of all railway road construction and geometrical parameter of road maintenance. This article analyzes investigated railway sub-ballast mixture properties from large sample sizes (n = 49): gradation, water permeability and density statistical parameters. The regression equation showing the relationship between the fully percent passing through sieves averages and standard deviations is presented. Her coefficient of determination (R2 = 0.909). The minimum number of representative samples of these three properties research is determined. Irregularity in most cases of water permeability (ν = 88,3%), depending on the laboratory tests methodology errors, is indicated. Santrauka Geležinkelio pobalastinis sluoksnis yra jungiamasis sluoksnis tarp balasto ir grunto sluoksnių. Šis sluoksnis turi užtikrinti tolygų apkrovos perdavimą į sankasą, nudrenuoti paviršinį vandenį, neleisti maišytis sluoksnių medžiagoms. Šių savybių užtikrinimas leidžia prailginti visos kelio konstrukcijos eksploataciją ir geometrinių kelio parametrų išlaikymą. Šiame straipsnyje yra analizuojamos užpildų mišinio, naudojamo geležinkelio pobalastiniame sluoksnyje, iš didelės imties (n = 49) gautos savybės: granuliometrinės sudėties, pralaidumo vandeniui ir tankio statistiniai parametrai. Pateikta granuliometrinės sudėties regresijos lygtis, rodanti sąsają tarp pilnutinių išbirų per sietus vidurkių ir standartinių nuokrypių. Jos determinacijos koeficientas R2 = 0.909. Apskaičiuoti reprezentatyvūs minimalūs bandinių skaičiai šioms trims savybėms tirti. Gauta, kad pralaidumo vandeniui savybė yra labiausiai nevienoda dėl laboratorinių tyrimų metodikos paklaidų, variacijos koeficientas (88,3 %). Raktiniai žodžiai:geležinkelio pobalastinis mišinys, granuliometrinė sudėtis, vandens pralaidumas, mišinio tankis, bandinių skaičius.

More and more recycled asphalt mixtures with high reclaimed asphalt pavement (RAP) content are used in road pavement. Having determined and evaluated RAP composition (aged bitumen content and aggregate gradation) and properties, a suitable recycling agent and virgin materials are selected in the design process. The gradation of hot mix asphalt (HMA) mixture that is recycled in an asphalt mixing plant (AMP) shall correspond to its optimal gradation set out in its job-mix formula (JMF). When RAP is recycled in an AMP, inevitable systematic and random errors of performed technological operations and inhomogeneity of virgin materials and RAP have a significant influence. These factors influence the variation of components quantities of recycled hot mix asphalt (RHMA) mixture and deviations from JMF. In this study, the principles of asphalt pavement hot recycling are systematized, which allows analysis of the factors of components’ interaction influencing the results of the recycling process. The paper also presents and analyses asphalt recycling technologies in AMP and their comparative analysis. During the season of asphalt mixture production in 2014, statistical parameters were calculated according to the data obtained from one of the companies, which collected and systematized RAP batch masses, when before batching it was pre-dried and pre-heated in an additional dryer. These parameters of batch mass and RAP content in RHMA position and variation were used when evaluating the accuracy and precision of the recycling process in AMP. The obtained data showed that when RHMA mixtures are produced in a modern batch-type AMP, RAP is batched accurately, but not precisely enough.

Bitumen should always be stored and handled at the lowest temperature possible, consistent with efficient use. At higher temperatures and lower viscosities pumping is optimized; whereas at lower temperatures and higher viscosities pumping efficiency decreases rapidly. Thus viscosity and its control by temperature is an important consideration in respect to all handling operations. The minimization of bituminous hardening during storing, transportation and mixing depends on careful control of binder temperature. TRA ASFALTAS 08 regulates maximum permitted storage temperatures of various bitumens. Heating equipment of periodical asphalt mixing plant (AMP) bitumen batching system (BBS) shall be designed to maintain the same temperature of the binder in the whole BBS. This article presents the study of heat transfer in bitumen storage tanks and identifies the most important factors influencing on energy loss. The test showed that energy loss in currently operated AMP is too high and may be reduced by changing technological parameters of bitumen heating, updating and upgrading separate heating equipment and improving temperature control and handling of heating equipment. The method of convection and radiation heat flow calculation in bitumen storage tank is presented. The findings obtained through the use of the described method of heat flow calculation correspond to the actual data of the consumed electrical power displayed on AMP computer.

This article is aimed at analyzing different methods of calculation of railway capacity of lines and applying them in “Lithuanian Railways”, improving efficiency of railroad traffic management by using new and modern technologies, integrated into the new Traffic Management Centre (TMC) and its related systems, allowing the compression of railroad traffic schedule and facilitating conflict resolution during planning time by using new technologies. To assure new traffic prevision for “Lithuanian Railways”, a new calculation method must be used, as today it is being used an old analytical method for capacity calculation on railway line, and this old calculation method does not allow the optimization of the use of the railway network. It is necessary to analyze new programming methods for calculating the train graph and its compression to adopt it in order to optimize the use of the network. This paper will present three methods used for calculating capacity consumption on railway lines and the results of applying one of them, the UIC 406 method, in a practice case. The practice case consist of adding two new trains in an already calculated schedule for the increment of the use of a line, using the new techniques for automatically detect the conflicts that appear after adding these new trains and solving the conflict. This paper will also present the statistical of how passenger’s train demand increases passengers flow.

The quality of multifaceted objects or phenomena can be hardly described or evaluated by a single criterion. The quality of the trip by train is described by a set of quantitative and qualitative criteria. The influence of all the criteria on the trip by international train may be evaluated by a comprehensive quality index (CQI) or quality index K. An additive model is offered for calculating CQI, which consists of the average weights of the criterion groups, as well as normalized weights and variables of the criteria, showing the correspondence of the real value of each criterion to the best, critical or allowable value. A mathematical model, which may be used for determining the quality of the trip by train based on the criteria describing the elements of the train and technical state of the railway track is also presented. Based on the use of 16 criteria describing the elements of the train and the parameters and the technical state of the railway track, the quantitative estimate KA (multiple criteria index) is obtained. The suggested model and the techniques used in the work may be applied to determining the quality or effectiveness of other objects or processes, which can be described by sets of criteria.

A system of road transport involves vehicles, roads, traffic participants and freight that therefore closely interact. The interaction between these material elements takes place in an external environment. The process of transportation is aimed at achieving some positive results, which could increase the efficiency of the Transport System (TS). However, negative effects such as a high accident rate cannot be avoided. The road accident rate is determined by the properties of the material elements of the TS and the parameters of their interaction. Their impact on the traffic accident rate cannot be determined by a planned experiment. They also cannot be compared quantitatively, because their units of measurement are different. The paper presents a detailed description of nine types of the interaction between TS elements belonging to three various levels. The data was given to 16 transport engineering specialists as a questionnaire for expert evaluation. The paper offers a logical control methodology for filling in the questionnaire based on the Analytic Hierarchy Process (AHP) and the sequence of calculations of the consistency of expert estimates in the process of determining the weights of the investigated interactions. The Kendall's coefficient of concordance has been used for calculating the weights assigned to the criteria by a group of experts and estimating the consistency of the ranks based on them. Finally, the paper presents a new method for evaluating expert judgements with reference to the use of the correlation analysis of ranks and weights. The significance of the calculated pairwise correlation coefficients has been validated by the Student's t-test and lowest value thus allowing us to consider that the expert opinions about the impact of the interaction of TS elements on the traffic accident rate are consistent. First Published Online: 24 Dec 2013

When exposed to destructive climate and weather factors and heavy vehicle loads, the pavement wears and deflects. In recent decades, apart from cracks and potholes, the depth of ruts grows and makes an increasing share of the pavement surface. The deeper are the tracks, the poorer are traffic conditions for fast-moving cars: drivers are struggling, speed is decreasing and the number of accidents is increasing. After track depth reaches a critical and permissible limit, the road surface must be repaired or speed limit has to be reduced. The work presents a theoretical analysis of track emergence causes and factors determining their depth. With the help of Mobile Road Research Laboratory RST 28, the track depth of all Lithuanian highways has been measured every 20 metres. The obtained data have been processed using the methods of mathematical statistics. Each road has a sample average of every rut, sample standard deviation and a coefficient of individually measured variation. The paper has drawn histograms, calculated skewness, kurtosis and normal distribution and provided lognormal distribution curves of a probability density function. The visualisation and empirical skewness and kurtosis values have revealed that the depth of the rut distributes according to lognormal rather than normal distribution. The average values of the roads having a dividing strip and standard deviations from the distribution across the road have been received. The given dependence of the rut depth of a standard deviation on the averages of rut depth shows an elastic interface of these parameters (determination coefficient R2= 0.741).

Engineering improvement of roads is in many cases inseparable from the improvement of at-grade intersections, as one of the most hazardous engineering structures. At-grade intersections in Lithuania are currently subjected to intensive installation of different traffic engineering and safety measures. More and more often, to ensure road safety the measures of experimental nature are used the effect of which has not been specified yet. Therefore, for the research object three intersections were selected provided with safety islands with flexible plastic reflective posts. The research was carried out within the zone of conventional intersections with the left-turn deceleration and waiting lanes on the main roads of Lithuania. During the research the driving speeds were measured in three different locations and the changes in the speeds and in the frequency of traffic conflicts were determined. Using an analogical comparison of similar traffic engineering measures, a preliminary effect of the study measures was identified.

Žvyrkeliai sudaro didesnę dalį viso kelių tinklo kai kuriose šalyse. Nepaisant tam tikros pažangos pastaraisiais metais, kelių eismo saugumas vis dar yra aštri problema. Eismo įvykių dažnumas keliuose priklauso nuo tokių veiksnių: kelių eismo apimties, eismo greičio, kelių būklės, oro sąlygų, vairavimo patirties ir eismo kultūros. Visi šie veiksniai yra susiję su eismo saugumu, žmonių sveikata ir gyvybe. Pagrindinis straipsnio tikslas yra pateikti eismo įvykių statistinę analizę ir ištirti Lietuvos regioninių žvyrkelių eismo įvykių priežastis, struktūrą, dinamiką ir sezoninį pobūdį. Eismo įvykiai keliuose priklauso nuo tam tikro sezono. Eismo įvykių daugėja nuo balandžio iki lapkričio dėl padidėjusio eismo intensyvumo dėl geresnių eismo sąlygų, ir piką pasiekia liepą. Eismo intensyvumas mažėja laikotarpiu nuo gruodžio iki kovo dėl prastėjančių eismo sąlygų ir atsargesnio kelių naudotojų elgesio. Lietuvoje kelių eismo įvykių smarkiai sumažėjo 2008 ir 2009 metais. Eismo įvykių analizė regioniniuose keliuose, turinčiuose žvyro dangą rodo, kad maksimalaus leidžiamo greičio sumažinimas nuo 90 km/h iki 70 km/h 2007 metais lėmė kelių eismo įvykių mažėjimą. Tačiau norint tai įrodyti, reikia papildomų tyrimų. Norint įvertinti 2008 m. kilusios ir dar tebesitęsiančios ekonominės krizės, bei eismo intensyvumo ir paviršiaus šiurkštumo poveikį eismo įvykių skaičiui, reikia tolimesnių tyrimų. A great number of serious road accidents occur all over the world every year. In spite of some progress in this area, road traffic safety has remained an acute problem in recent years. Traffic accidents on the road depend on the following factors: road traffic volume, road traffic speed, road condition, weather conditions for traffic, driving experience and driving culture. All these factors are related to traffic safety, human lives and health. The main goal of this work is to provide a statistical analysis of traffic accidents and investigate the causes, structure, dynamics and seasonal character of traffic accidents on Lithuanian regional gravel roads. It has been established that seasons play an important role for traffic accidents on regional gravel roads in Lithuania. Rates for traffic accidents increase from spring to autumn. The number of traffic accidents on Lithuanian roads decreased considerably in 2008 and 2009.

Numerous alternatives exist for foundation systems and construction technologies. The systems can be described by different criteria values which are incorporated in the conventional design process. Decision on the most suitable construction technology is vital for success and depends on many effectiveness criteria. The business success depends on the right choice. The mandate of a construction management researcher is to use rational, systematic, science-based techniques to inform and improve various decisions. The paper presents multiple criteria decision making model for selection of a pile-column technology. The technological criteria are determined by an experimental study. Based on in-situ investigation of natural soil conditions, criteria values are determined. The decision making model incorporates five different methods and techniques. To solve a problem, it uses three multiple criteria decision making methods. Integrated criteria weights are determined by using the analytic hierarchy process and the expert judgement method. This model could be used to solve complicated problems pertaining to the selection of a construction technology.

Decision making is a vital component of success in construction management. All construction businesses recognize the painful necessity of technology choice. Good decisions mean good business. Decisions that are based on knowledge and sound reasoning can lead a company into long-term prosperity. The mandate of a construction management researcher is to use rational, systematic, science-based techniques to inform and improve decisions of all kinds. The paper presents results of an experimental study on technological indicators of pile-columns at a construction site. Based on in-situ investigation of natural soil conditions, regression equations have been determined, which can be very useful when planning similar works at a construction site. Besides, they allow determining duration and energy consumption of construction works.

The significance of the criteria describing various aspects of travel by train, e.g. passenger transportation comfort, safety, travel time, price of a journey, etc., differs considerably. The quality of particular trains, track sections and staff performance can be successfully evaluated by a single number, using the comprehensive quality index (CQI). The paper offers an additive model to calculate the normalized weight coefficients of particular criteria for CQI calculation. A multi-criteria mathematical model, which may be used for evaluating the significance of the criteria describing organization and technology of travel by train for determining its quality, is also presented. Based on the nineteen adopted criteria (the criteria of group B), reflecting the organization and technology of travel by train, the quantitative estimateKBis obtained. Case studies of calculating the comprehensive quality indexKB, describing the organization and technology of travel by the train ‘Vilnius–Moscow’, which show the real quality of these processes, are presented. Finally, the conclusions based on the research results are provided. First Published Online: 19 Sep 2012

Smoothness is the main feature of road exploitation. It particularly affects movement speed, safety and driving comfort. Evenness of the road belongs of three factors: strength of the pavement construction, heavy vehicle traffic and the impact of the axle mass over it’s term of exploitation. The main negative influence on Lithuanian roads has a overloaded heavy vehicle in excess of the permissible axle load limits. Static and dynamic vehicle weighing equipment and technologies were presented in the article. This article explores overloaded heavy vehicle damage done to Lithuanian roads and its intensity increase. Discuss the basic preventive techniques and methods to prevent the rapid wear of pavements. Also analysis of changes in axial load data through the 2009 August is done. Santrauka Pagrindinis kelio dangos eksploatacinis rodiklis yra lygumas. Nuo jo priklauso važiavimo greitis, saugumas ir komfortiškumas. Didžiausią įtaką kelio lygumo kitimui turi jo dangos konstrukcijos stipris, sunkiųjų transporto priemonių eismo intensyvumas ir ašių masė per visą eksploatavimo laikotarpį. Pagrindinę neigiamą įtaką Lietuvos keliams daro perkrauti krovininiai automobiliai, viršijantys leistinąsias ašių apkrovų normas. Straipsnyje nagrinėjama viršsvorinio krovininio transporto daroma žala Lietuvos keliams. Išanalizuoti dinaminio ir statinio automobilių svėrimo įrenginiai ir technologija. Nustatytas 55-tos klasės sunkiųjų automobilių viršsvorinio krovininio transporto apkrovų kitimas ir jo intensyvumo didėjimas. Aptarti pagrindiniai prevenciniai būdai ir metodai, leisiantys sumažinti spartų kelio dangos nusidėvėjimą. Išanalizuoti varančiosios ašies ašinės apkrovos kitimo duomenys per 2009 m. rugpjūčio mėn. laikotarpį. Raktiniai žodžiai: sunkieji automobiliai, viršsvorinė transporto priemonė, varančioji ašis, ašinė apkrova, perkrovos dydis, kelio danga

Economy and nonproductive sectors of each country could not function without a transport system (TS). Having analysed research works on the interaction of separate TS elements, it was identified that there is no common model for all types of interaction. TS consists of material (physical) objects: traffic participants and freight to be carried, a transportation process and operations’ control. TS classification scheme devised according to systematically selected criteria, showing that several criteria are often applied at the same time in official documents, is presented. Original TS physical elements’ interaction model with 6 interaction levels is presented as well. The model is suitable for all modes of transport. Six levels of interaction are distinguished: autointeraction of transport elements, the first level; TS elements’ interaction, the second level; TS elements’ interaction with external environment, the third level; interaction of transport modes, the fourth level; TS interaction with the country's economy and nonproductive sectors, the fifth level; and TS impact on the country's GAV (Gross Added Value), the sixth level. Properties and factors influencing on the results and parameters of interaction have been systematized. Levels and properties of interaction have been analyzed as well. To evaluate the importance of interaction levels to the parameters of the transportation process, the method of Analytic Hierarchy Process (AHP) has been recommended. Santrauka Kiekvienos šalies ūkio ir negamybinės veiklos sektoriai negalėtų funkcionuoti be transporto sistemos. Išanalizavus mokslo darbus, skirtus atskirų transporto sistemos elementų sąveikai tirti, nustatyta, kad visas sąveikos rūšis vienijančio modelio nėra. Transporto sistemą sudaro materialūs (fiziniai) transporto objektai: eismo dalyviai ir kroviniai, kuriuos reikia vežti, transportavimo procesas ir veiklos reguliavimas. Pateikta transporto sistemos klasifikavimo pagal sistemiškai pasirinktus kriterijus schema, rodanti, kad oficialiuose dokumentuose dažnai vienu metu taikomi keli kriterijai. Pateiktas originalus transporto sistemos fizinių elementų sąveikos modelis, kuriame išskirti šeši sąveikos lygmenys. Modelis tinka visoms transporto rūšims. Pirmajam lygmeniui priskirta transporto elementų autosąveika, antrajam—transporto sistemos elementų tarpusavio sąveika, trečiajam—transporto sistemos elementų sąveika su išorine aplinka, ketvirtajam—transporto rūšių sąveika, penktajam—transporto sistemos sąveika su šalies ūkio ir negamybinės veiklos sektoriais, šeštajam—transporto sistemos įtaka šalies bendrajai pridėtinei vertei. Susisteminti sąveikos požymiai ir veiksniai, turintys įtakos fizinės sąveikos rezultatui ir jos parametrams. Išanalizuoti sąveikos lygmenys ir jos savybės. Sąveikos lygmenų prioritetui (svarbai) transportavimo proceso parametrams vertinti pasiūlyta taikyti Analytic Hierarchy Process (AHP) metodą, kurio pagrindą sudaro elementų porinio lyginimo matrica. Skaičiuojamajame pavyzdyje nustačius transporto sistemos elementų skirtingų lygmenų sąveikos svorį kelių transporto saugumui įrodytas AHP metodo tinkamumas transporto sistemos elementų sąveikai modeliuoti. Резюме Различные секторы хозяйственной и непроизводственной деятельности любого государства не могли бы функционировать без транспортной системы. На основе анализа научных трудов, посвященных исследованиям взаимодействия отдельных элементов транспортной системы, установлено, что не существует модели, объединяющей все виды и уровни взаимодействий. Транспортная система включает в себя разные материальные (физические) объекты. Это участники движения и грузы, которые необходимо перевозить, транспортный процесс и регулирование деятельности. Приведена схема классификации транспортной системы по системным подходам, установленным критериям, свидетельствующая о том, что зачастую в официальных документах одновременно применяется несколько критериев. Предложена оригинальная модель взаимодействия физических элементов транспортной системы, в которой выделены 6 уровней взаимодействий. Модель пригодна для всех видов транспорта. Первый уровень присвоен взаимодействию транспортных элементов, т. е «внутреннему» взаимодействию однородных материальных элементов транспортной системы, второй – взаимодействию материальных составляющих элементов транспортной системы, третий – взаимодействию материальных составляющих элементов транспорта с внешней, окружающей средой, четвертый – взаимодействию различных видов транспорта, пятый – взаимодействию транспортной системы с секторами хозяйственной и непроизводственной деятельности страны, шестой – влиянию взаимодействия транспортной системы c сектором экономики, а также влиянию непроизводственной деятельности страны на экономику (внутренний валовый продукт), предопределяющую прожиточный уровень населения. В модель включено влияние науки и исследований. Систематизированы признаки и факторы, оказывающие влияние на результат физического взаимодействия элементов транспортной системы и ее параметры. Выполнен анализ уровней взаимодействия и его свойств. Для определения приоритета (весомости) различных отдельных уровней взаимодействия на параметры процесса транспортирования предлагается применять метод анализа иерархий (Analytic Hierarchy Process), основу которого составляет матрица попарного сравнения элементов. На примере расчета весомости различных уровней взаимодействия элементов транспортной системы, влияющих на безопасность дорожного транспорта, доказана пригодность -метода AHP для моделирования взаимодействия элементов транспортной системы. Reikšminiai žodžiai: transportas, elementai, sąveika, modelis, sistema, išorinė aplinka, AHP metodas Ключевые слова: транспорт, элементы, взаимодействие, модель, система, внешняя окружающая среда, метод анализа иерархий

The article presents reclaimed asphalt pavement (RAP) processing technologies and equipment models used in the asphalt mixing plant (AMP). The schematic model indicating all possible ways to process RAP in AMP is shown. The model calculating the needed temperature of mineral materials used for heating RAP is given and an example of such calculation is provided. Article in Lithuanian Asfalto dangos regeneravimo asfaltbetonio maišytuvuose technologijų modeliavimas Santrauka Pateikiamas asfaltbetonio maišytuve regeneruojamo senos kelio dangos asfalto technologinių operacijų sekos ir įrenginių komponuotės modelis. Sudarytas scheminis modelis, kuriame susisteminti visi galimi regeneruoto karšto maišymo asfalto (KMA) mišinio gamybos asfaltbetonio gamykloje būdai. Pateiktas mineralinių medžiagų, perduodančių šilumą naudoto asfalto granulėms (NAG), reikiamos temperatūros skaičiavimo modelis ir jo skaitinis pavyzdys. Reikšminiai žodžiai: naudoto asfalto granulės (NAG), karšto maišymo asfalto (KMA) mišinys, mineralinės medžiagos, asfaltbetonio maišytuvas, džiovinimo būgnas, regeneruota asfaltbetonio danga (RAD), šilumos pernaša.

Some particular aspects such as the improvement methods of technological parameters for hot bitu‐ men storage in a pipeline transport system, transportation and dosed supply to batch asphalt mixing plant (AMP) are evaluated in this paper. Bitumen in asphalt concrete binds together the material of mineral particles into a strong conglomerate of a complicated structure, capable of withstanding the destructive effect of vehicles and the factors on the road pavements. The optimal amount of bitumen determined by calculation and laboratory testing should be maintained in mix batches of hot‐mix asphalt (HMA) obtained from AMP mixer. In the periodic type of the asphalt concrete blender mass of the weighted matrix in the all merging batcher's tanks should correspond in percents equally in the HMA to the designed amount of the job‐mix formula (JMF). The bitumen batcher does not always weigh bitumen portions precisely. Their mass deviations from the amount determined by JMF and its variation impair HMA composition and performance. In addition,, an additive model for calculating the effect of factors causing the variance of bitumen content in the produced HMA mixture is presented in this current paper as well. The data on statistical evaluation of bitumen batcher's modernization performed at certain Lithuanian Enterprise are discussed. The differences in structures of reconstructed and not reconstructed bitumen batching systems (BBS) are analysed and methods of determining modernization effectiveness are presented. The effectiveness of BBS is analysed too, defining the deviations of bitumen content in subsamples, taken and extracted everyday for two seasons (before and after the batcher's modernization) of HMA mixture production from the value of JMF and comparing them to the values of tolerances. The analysis of column charts and histograms shows that the made modernization helped to increase the precision of supplying the required amount of bitumen to HMA mixture insignificantly. However, the control of BBS has been considerably increased. First published online: 10 Feb 2011

In most countries, the pavement of motor roads, airfields and other trafficked areas is made of hot‐mix asphalt (HMA) mixture prepared by asphalt mixing plants (AMP) of various designs. The total output of HMA mixtures shows the dynamics of national road transport infrastructure's development, corresponding to the increasing number of vehicles, traffic intensity and axle loading. HMA mixtures are made by using various technologies, which have some advantages and disadvantages. The paper presents technological schemes of making HMA mixtures used in Lithuania and other countries. The development of AMP and technical and technological characteristics of new computer‐aided AMP models used at various asphalt production companies (APC) were analysed. Based on the data provided by the European Asphalt Pavement Association (EAPA), the correlational‐regression relation between the country's area and the amount of the produced HMA mixtures was established. The data on the total output of HMA mixtures in Lithuania cannot be found in the information provided by EAPA. For the first time, the dynamics of the production of HMA mixtures by particular APC in Lithuania over the last 10 years (1998–2007) has been determined based on the data directly obtained from their manufacturers. The data were analysed and compared to the output of HMA mixtures in other countries and the dynamics of the development of AMP models used in Lithuania and changes in their numbers were determined. Santrauka Daugelyje šalių automobilių kelių, skridimo aikštelių ir kitų eismo zonų danga įrengiama iš karšto maišymo asfalto (KMA) mišinio, pagaminto skirtingos konstrukcijos asfaltbetonio maišytuvuose (ABM). KMA mišinio gamybos apimtys rodo šalies kelių transporto infrastruktūros plėtros dinamiką ir atitiktį didėjantį automobilių skaičių, jų eismo intensyvumą ir ašies apkrovas. KMA mišinys gaminamas taikant skirtingas technologijas, turinčias privalumų ir trūkumų. Darbe pateiktos Lietuvos Respublikos ir kitų šalių KMA mišinių gamybos technologijos schemos. Išanalizuota ABM tobulinimo raida ir įmonėse veikiančių naujų modelių kompiuteriais valdomų ABM techninės ir technologinės charakteristikos. Naudojant European Asphalt Pavement Association (EAPA) duomenis, gauta koreliacinė-regresinė šalies ploto ir pagaminto KMA mišinio kiekio sietis. EAPA skelbiamoje informacijoje nėra duomenų, rodančių suminius Lietuvoje pagaminto KMA mišinių kiekius. Pirmą kartą iš asfalto mišinių gamintojų surinkus ir susisteminus duomenis, tiesiogiai gauta 10 metų (1998–2007) Lietuvos Respublikos asfaltbetonio gamyklose (ABG) pagaminto KMA mišinių kiekio dinamika ir ji palyginta su kitose šalyse pagaminto KMA mišinio kiekiais. Atlikta Lietuvoje veikiančių ABM modelių ir skaičiaus kaitos dinamika. First Published Online: 14 Oct 2010 Reikšminiai žodžiai: karštai maišytas asfaltas, asfaltbetonio maišytuvas, asfaltbetonio gamykla, periodinio veikimo maišytuvas, produkcijos dinamika, technologiniai procesai.

Multi-attribute methods in road construction can be used on the national, organization and project levels. However, most assessment methods are seeking to find how to make the most economic construction decisions, and most of all these decisions are intended only for economic objectives. Computerised Asphalt Mixing Plants (AMP) are one of the most expensive and complicated equipments for construction of road pavements. Modern AMP is controlling by computer program, but there are still some problems. Properties of the AMP not always satisfy demands and requirements of road constructors. Quality of the asphalt hot mixtures, environmental contamination, pollution, firm economic well-being and possibility to satisfy demands of hot asphalt mixture users depend on the AMP quality. This paper proposes a multi-attribute model for efficient quality assessment of the AMP. For this problem were selected 9 main quality attributes and weighted by expert ranking method. The problem is solved by applying additive assessment. Also, a case study is presented.

The history of the Department of Transport Technological Equipment of the Vilnius Gediminas Technical University is presented. Research areas and transport engineering scientific problems which are worked out by the scientists of department are mentioned., Lietuviška santrauka. Straipsnyje pateikta Vilniaus Gedimino technikos universiteto Transporto technologinių įrenginių katedros trumpa istorija. Vardinamos mokslinės veiklos kryptys ir siūlomos paslaugos. Vaizdžiai demonstruojami mokslinių tyrimų rezultatai.

A new classification of asphalt concerete pavement defects is presented in the article and the causes of their development are systematised. The dynamics of asphalt concrete pavement defect development in the road and the dependence of pavement deterioration on the type of defects are presented in the theoretical graphic model. The change of road pavement structural strength (stiffness modulus) depending on the pavement service life is also described. The dependence of the level of asphalt concrete pavement on the most important roads of the Republic of Lithuania (road Vilnius-Kaunas [Al] and motorway Vilnius Panevėžys [A2]) measured with one-wheel dynamometric trailer PKRS-2U (Russia) on the level of pavement deterioration has been identified through experiments. The analysis of the dependence of transport costs and driving speed on road pavement level has been carried out. Regression equations of such dependence and correlation coefficients as well as relations are presented too. Frist Published Online: 30 Jul 2012

The duration of asphalt concrete functioning depends on the quality of the asphalt concrete mixture used to pave the road. Grading of hot fractions sieved through technological sieves of asphalt concrete mixture, their pollution with particles of different size as well as stability influence on the quality of an asphalt concrete mixture.Eachj – ( j= 1....,m) aggregate mineral material or mixture is made up of two (mineral powder, particle of size less than 0,09 or 0,071 mm, and sand, particle of size from 2 to 0,09 mm or 5-0,071 mm) or three (crushed stone, particle size is larger than 2 or 5 mm) mineral components (i= 1, ...,k) . When required technological operations of asphalt concrete mixture production are carried out, the quantity and stability of anyi – component in mineral materials change when they move through an asphalt concrete mixer. The more stable the quantity of mineral components in mineral materials (especially in finally dosed) is, the more uniform the composition of asphalt concrete mixture is produced. The experiments showed that when asphalt concrete mixture is produced applying a traditional technology in an asphalt concrete mixer of model D-597, D-508-2A, D-645-3 and D-590, sieved hot fractions of 0–5 mm and 5–15 are polluted with particles of different size by more than 10 per cent; and this pollution is neither uniform nor stable. Following a well-known theory, an average quadratic deviation σ of arithmetic undersized particles sieved through laboratory sieves ~ aggregate mineral materials is the greatest when their mean Xmakes up 50 per cent; therefore, hot fractions of 0–5 mm and 5–15 mm were produced on the experimental data obtained from production as well as regression equations σ = ƒ(X) of statistical indeces of cold mineral powder. The values of average quadratic deviations σµijof mineral component quantities in those finally dosed mineral materials are obtained from curves drawn according to the regression equations. They can be used to estimate dispersion σ2Gi of mineral componentiin asphalt concrete mixture which depends on the accuracy and stability of technological factors of an asphalt concrete mixer. Article in Lithuanian. Galutiniai dozuojamose mineralinėse medžiagose esančių asfaltbetonio komponentų stabilumo nustatymo teoriniai principai ir eksperimentiniai duomenys Santrauka. Atliktais eksperimentiniais tyrimais nustatyta, kad gaminant asfaltbetonio mišinį pagal klasikinę technologiją D-597, D-508-2A, D-645-3 ir D-590 modelio asfaltbetonio maišytuvuose, išsijotos karštosios 0–5 mm ir 5–15 mm frakcijos yra užterštos kitų matmenų grūdeliais daugiau kaip 10 % ir ši tarša nėra vienoda bei pastovi. Remiantis žinoma teorija, kad biriosios mineralinės medžiagos suminių išbirų per kontrolinius sietus vidutinis kvadratinis nuokrypis σ yra didžiausias, kai jų vidurkis X sudaro 50 %, iš gamyboje gautų eksperimentinių duomenų sudarytos 0–5 mm ir 5–15 mm karštosios frakcijos, taip pat šaltųjų mineralinių miltelių šių statistinių rodiklių regresijos lygtys σ =ƒ(X). Iš pagal regresijos lygtis nubraižytų kreivių gautos šiose galutiniai dozuojamose mineralinėse medžiagose esančių mineralinių komplektų kiekių vidutinių kvadratinių nuokrypių σµij vertės. Jas galima panaudoti apskaičiuojant asfaltbetonio mišinio i-ojo mineralinio komponento kiekio dispersiją σ2Gi, priklausančią nuo jo gamybos asfaltbetonio maišytuve technologinių veiksnių tikslumo ir stabilumo. Raktažodžiai: asfaltbetonio mišinys, asfaltbetonio maišytuvas, karštosios frakcijos, sijojimo kokybė, granuliometrinės sudėties stabilumas, variaciją remiantis veiksniai. First Published Online: 19 Oct 2011

Multi-attribute methods in road construction can be used on the national, organization and project levels. However, most of assessment methods are seeking to find how to make the most economic construction decisions, and most of all these decisions are intended only for economic objectives. Computerised Asphalt Mixing Plants (AMP) are one of the most expensive and complicated equipments for construction of road pavements. Modern AMP is controlling by computer program, but there still are some problems. Properties of the AMP not always satisfy demands and requirements of road constructors. Quality of the asphalt hot mixtures, environmental contamination, pollution, firm economic wellbeing and possibility to satisfy demands of the hot asphalt mixture users depends on the AMP quality. This paper proposes a multi-attribute model for efficient quality assessment of the AMP. For this problem were selected 9 main quality attributes and weighted by expert ranking method. The problem is solved by applying additive assessment. The case study is presented also.