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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.

Long-distance transportation of passengers is usually performed by air and rail transport. The time and cost of the trip, as well as quality and variety of services and other economic criteria, strongly infl uence the choice of one of the competing transport facilities. The quality of the trip by train is determined by the criteria of four groups associated with the vehicle elements and the state of the railway line, organization of the trip by train, its technology, the price of the trip and the provided services (PTPS) and safety of the trip by train. The paper presents a model of the major component of the comprehensive quality index (CQI), characterizing a trip by an international train from such aspects as the PTPS. Based on using the analytic hierarchy process (AHP), the weights of these criteria groups and the weights of the criteria of each group are determined. A survey of the respondents of three categories, including passengers, service staff of the train and the administration staff of the joint-stock company, is conducted to know their opinions about various aspects of the trip described by the considered criteria. The model is based on the average weight and the weights of six criteria of the group, describing the PTPS, which are multiplied by the calculated variables. This allows the quality of the trip by train, depending only on these criteria, to be expressed in a single number. The numerical example shows that the suggested model yields reliable data and can be used in practice for evaluating the quality of trips by various international trains.

The relationship between the static and dynamic deflection modulus is presented in the paper, and a correlation between the FBL physical and strength indicators is determined. The correction coefficients of dynamic measurements, as related to static beam readings, are presented. The results show that, in the absence of a static beam, static beam readings can be replaced by the readings of any of the three analysed dynamic devices, and the FBL strength can thus be measured.

In Lithuania, the efforts are made to ensure the conditions of safe, comfortable and fast passenger and freight transportation on Lithuanian roads, satisfying geometric characteristics of their particular categories and the specified requirements to their pavement. The considered characteristics of pavement include its roughness, strength and the admissible rut depth and destruction level. Rest and Service Areas (RSAs) are usually set up at the roadside. The paper presents a description of the conditions specified for the movement of motor vehicles on the major Lithuanian roads in the seasons of warm weather and a Classification Model (CM) of the required conditions. It also provides the results of the evaluation of actual Travel Conditions (TCs) on the main Lithuanian roads by using the developed model. The obtained results show that in 2016 on the considered highways were good and very good, except for road A9, where the TCs were satisfactory. It is demonstrated that the distances between RSAs comply with the recommended distances. It is also shown that roughness of pavement and strength of the Structure of the Pavement (SP) depend on the destruction or damage level of pavement. The values of such pavement parameters as roughness, rut depth and destruction level, which should not be exceeded because they help to ensure either comfortable or good TCs on Lithuanian highways, are given. The suggested model of road TCs can be used for determining the quality of TCs on highways. Keywords: motorways, travel conditions, structure of the pavement, pavement, rest and service areas, roadside landscape.

Asphalt mixture gradation homogeneity is one of the key factors for proper laying and compaction during road pavement and its long-term maintenance afterwards. To achieve the good quality asphalt mixture homogeneity of aggregates used in road pavement must be kept in mind. Regarding to this, gradation variation of five different granite aggregates fractions (0/2, 2/5, 5/8, 8/11 and 11/16) from one of the largest manufacturing plants in Lithuania were determined in this paper. Total of 244 samples were taken from conveyer belt at the manufacturing place and all the data was evaluated by statistical methods providing histograms with theoretical curves of normal distribution. After that, the results were compared to each other and the requirements issued by Lithuanian road administration authority. Regression analysis was used to determine the dependence of standard deviation of percent passing and the mean percent passing through the sieves. The obtained research findings revealed that the maximum value of standard deviation of this dependence was equal to mean of 50% percent passing. Further investigations should include other aggregates quality parameters variation and its homogeneity throughout different stages of technological and transportation processes. DOI: https://doi.org/10.3846/enviro.2020.601

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

The transport system must increase the mobility of the national population, gross domestic product (GDP) and remain environmentally friendly and safe. Rail transport is increasingly becoming popular for both long-distance freight and passengers. This trend is affected by an increase in safety travelling by train, which significantly improves the quality of the trip. The paper presents a mathematical model that allows calculating a share of the indicator for the quality of traveling by international train, which depends on the impact of criteria for internal safety in the carriage. The weights of eight sub-criteria for the main criteria falling into group D have been determined applying the Analytic Hierarchy Process (AHP) method, whereas their variables have been estimated using original formulas. The resolved numerical example admits that the introduced model is suitable and convenient to be employed in practice assessing the quality of the international train in a single number. The actual data on the international train Vilnius-Moscow indicating the adequacy of internal security measures have been used for the numerical example.

Rail transport, in competition with other modes of transport, has to improve the quality of passenger and freight transport. In order to carry passengers and goods quickly, efficiently and safely, it is necessary take maintenance railways so that their geometric parameters do not exceed the tolerances. About real railway track condition, the data is obtained by track geometry recording car, measuring seven geometric parameters dispersion. This paper presents the methodology for determining and estimating the geometric parameters of the track geometry, which shows that the track quality index (TQI) is the sum of the variance of seven geometric parameters. Experimental research on the two-track A (8km) and B (11km) a three-year period (2015-2017) for all 12-month KKI, establish their quality dynamics (change over time). These data indicate that the quality of the analyzed sections A and B was good, but due to the increasing mass (in megatons) of transported loads, there is a tendency to deteriorate. Article in Lithuanian. Geležinkelio kelio geometrinių parametrų dinamikos tyrimas taikant kelio kokybės indeksą Santrauka Geležinkelių transportas, konkuruodamas su kitomis transporto rūsimis, privalo gerinti keleivių ir krovinių vežimų kokybe. Norint greitai, efektyviai ir saugiai vežti keleivius ir krovinius, būtina taip prižiūrėti geležinkelių kelius, kad jų geometrinių parametrų nuokrypiai nevirsytų leidžiamųjų nuokrypių. Apie tikrąją geležinkelių kelio būkle duomenys gaunami kelmaciu ismatavus septynių geometrinių parametrų sklaidą. Siame darbe pateikta geležinkelio kelio geometrinių parametrų sklaidos nustatymo ir vertinimo metodika, kurioje įrodyta, kad kelio kokybės indeksas (KKI) yra septynių geometrinių parametrų dispersijų suma. Eksperimentiskai istyrus dviejų geležinkelio kelių A (8 km) ir B (11 km) trijų metų laikotarpiu (nuo 2015 iki 2017 metų) visų 12 mėnesių KKI, nustatyta jų kokybės dinamika (kaita bėgant laikui). Sie duomenys rodo, kad istyrinėtų A ir B ruožų kelio kokybė buvo gera, bet dėl didėjancios pervežtų krovinių suminės masės (megatonų skaiciaus) turi tendenciją blogėti. Reiksminiai žodžiai: geležinkelių kelias, geometriniai parametrai, sklaida, dispersija, nuokrypiai, kelio kokybės indeksas (KKI), eksperimento duomenys, dinamikos įvertinimas.

Railway ballast (RB) layer has to limit tie movement by resisting vertical, lateral and longitudinal forces from the train and the track, to reduce the stresses from train loads applied to the subgrade, thus limiting permanent settlement. It also has to provide immediate water drainage from the track structure, to aid in alleviating frost problems, to facilitate maintenance surfacing and lining operations, to provide support for ties with the necessary resilience to absorb shock from dynamic loads. Secondary functions include retarding vegetation and resisting effects of fouling from surface deposited materials, absorbing airborne noise, providing adequate electrical resistance between rails, facilitating the redesign or reconstruction of the track. These properties are obtained through the use of proper gradation crushed granite, by determining its proper laying and compacting technological parameters, by ensuring sufficient thickness and profile of the layer. This paper presents statistical investigations of the four samples of crushed granite taken from transporter belt (TB), plant stockpile (PS), wagon (W) and railway construction (RC) uncompacted layer used to RB course. The gradation (particle size distribution), density of crushed granite particles (DENP), water absorption (WA24), Deval index (MDE), Los Angeles coefficient (LARB coefficient) and resistance to crushing (SZRB) of four samples were measured. Statistical parameters of crushed granite qualitative indicators, histograms, theoretical curves of normal distribution are presented. Their compliance with normal distribution was verified by employing the criteria of skewness, kurtosis, Pearson, Shapiro-Wilk and Kolmogorov-Smirnov. Dependance of standard deviations of percent passing through sieves on the means of percent passing through these sieves was obtained from regression analysis. The use of Kruskal-Wallis test by ranks showed that means obtained in different sample-taking locations did not differ statistically. The maximum value of standard deviation of this dependance, equal to mean of 50% percent passing, was used to evaluate the homogeneity of crushed granite used to construct the ballast layer according to the variation of its gradation. Absolute allowable error of minimum sample size n, equal to 5%, 10%, 15% and 20%, was calculated. Investigation results indicated that due to segregation the homogeneity of the gradation of crushed granite used to construct the ballast layer from its production site to its exploitation site decreased by 78%. During the technological processes of loading, transporting and spreading the gradation has hardly changed.

Mineral resources and aggregates used in transport infrastructure or any other purposes importance is undeniable. Its usage and extraction not only benefits economics and social environment, but also should be sustainable. Regarding to this, analysis of Baltic countries mineral resources and aggregates extraction was conducted. The main purpose of the article is to analyze mineral resources situation in each of the country and provide extraction data for aggregates used in transport infrastructure. Mining and quarrying sector is evaluated in whole country economic picture and period 2008-2020 was analyzed by combining data from all the Baltic countries for aggregates extraction. The article is valuable by putting all Baltic countries in one perspective and sharing newest data. Further investigations could include analysis of factors for aggregates demand and its forecast.

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 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 addresses simulation of asphalt on the macroscopic scale, using the Discrete Element Model (DEM). Asphalt mixture is considered as a particulate solid composed of relatively stiff deformable layered spherical particles embedded into a homogenised matrix. The discrete model presents a 3D network of one-dimensional elements connecting particle's centres and comprising mutual interaction of particles. The contribution of the film layer and the interface thickness for normal stiffness is described analytically and illustrated by simulation results. Development of the normal interaction model of layered particles contacting via interface on the meso scale is the key point of the current development. The model applied aiming to simulate deformation of asphalt mixture is able to capture properties of the weaker matrix interface while layered particle comprises of bitumen film in meso scale. The developed technique is applied for simulation of Marshall test, i.e. diametric compression of cylindrical specimen, widely used for characterisation of asphalt mixtures. Finally, suitability of the model is illustrated by comparison with the available experimental results.

The paper aims to determine the quality of the trip by train, which depends on the number of factors described by four groups of criteria. Each group includes individual criteria. The weight of the criteria of each group describing the quality of the trip by train is different. It is determined by using Kendall’s rank correlation method. The normalized weights of sixteen criteria of the group A, describing the elements of the train and the state of the railway track, are found based on the analytic hierarchy process (AHP) method. They are used in the original additive mathematical model, allowing the quality of the trip by train to be expressed by a single value – the multiple criteria index. The weight of each criterion is multiplied by its dimensionless variable calculated by comparing the real criterion value to its best, worst or allowable (standard) value. The validity of the developed mathematical model is checked by using the data on the technical state of the elements of the international train ‘Vilnius-Moscow’ and the railway track obtained on the territory of Lithuania.

In methodologies of solving different transport problems where the best decision has to be determined usually a number of chosen quantitative criteria are incorporated, which describe qualitative parameters of transport systems in quantitative terms. Often weights which reveal importance of such criteria must be evaluated. The realm of proprietary methods used in engineering sampling and experimental studies does not comprise methods of weight evaluation. Consequently, expert evaluation methods, which elicit weights of criteria from experienced, qualified and fair experts, are used. Among the most popular such methods is the method AHP (Analytic Hierarchy Process). Scientists of Vilnius Gediminas Technical University used this method for investigation of interrelationship of elements of a transport system; for evaluation of influence of the interrelationship on road traffic safety; and for evaluation of quality of passenger railway transportation service.

Bitumen holds the aggregate in hot mix asphalt (HMA). Without asphalt binder, HMA would simply be crushed stone or gravel. A bitumen batching system (BBS) is comprised of bitumen storage, transportation, weighing and discharge equipment in an asphalt mixing plant (AMP). The function of the equipment is to batch the binder heated up to working temperature and to discharge it into a mixer in batches. In the entire system, the binder is exposed to high temperature and oxygen. Bitumen is slowly oxidized when it is in contact with oxygen. The degree of oxidation is highly dependent on temperature, time and thickness of a bitumen film. This article models the key factors influencing on the dynamics of bitumen oxidation in BBS equipment. Stone mastic asphalt (SMA) mixture was produced from the same materials according to the same job-mix formula (JMF) in neighbouring batch type AMP by changing the mixing time of materials from 20 to 60 s. Bitumen binder was separated from the taken SMA samples and its gradation was identified. Thus, Marshall specimens were produced and tested. PenetrationPen25of bitumen binder recovered in rotary evaporator, softening pointTspwas determined and penetration indexIpwas calculated. The presented findings of experimental investigation show that the properties of bitumen binder in BBS working at two different technologies changed inconsistently. Due to gravitation, the bitumen intensively flowing into a mixer (BBS1) is impacted by oxidation more than the bitumen batched by a high-pressure pump (BBS2).

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.

The paper analyses waste tyre rubber treatment technologies. According to foreign countries and Lithuanian experiment results, positive and negative features of the utilization methods are presented. Data of experiments is presented using tyre rubber in clinker burning furnaces. Here is also information on the use of rubber additive in concrete and the impact to road design. Formulated conclusions. Santrauka Nagrinėjamos naudotų padangų regeneravimo ir utilizavimo technologijos. Remiantis užsienio šalių ir Lietuvoje atliktais tyrimais, pateikiamos pozityvios ir negatyvios metodų savybės. Pateikta informacija ir duomenys, gauti deginant gumą klinkerio krosnyse. Taip pat duomenys apie gumos panaudojimą betone ir poveikį kelio dangos konstrukcijai. Suformuluotos išvados. Raktiniai žodžiai: padangų perdirbimas, guma, deginimas, termolizė, modifikuotasis betonas, utilizavimas, akustinės charakteristikos, lenkimo deformacija, pirolizė

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).

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 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.

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.

Mokomojoje knygoje nagrinėjama kelių transporto sistemos infrastruktūros sudedamoji dalis – automobilių keliai ir jų statiniai. Atskleista transporto sistemos paskirtis ir reikiamos savybės, išanalizuoti automobilių kelio elementai, jo dangos konstrukcija, mazgai, sankirtos ir sankryžos. Leidinys parengtas ir išleistas už Europos struktūrinių fondų lėšas, jomis finansuojant VGTU Transporto inžinerijos, Biomechanikos ir Aviacinės mechanikos inžinerijos projektą „Studijų programų atnaujinimas pagal ES reikalavimus, gerinant studijų kokybę ir taikant inovatyvius studijų metodus“ pagal Lietuvos 2007–2013 m. Žmogiškųjų išteklių veiksmų programos 2 prioriteto „Mokymasis visą gyvenimą“ VP1-2.2-ŠMM-07-K priemonę „Studijų kokybės gerinimas, tarptautiškumo didinimas“. Projekto kodas Nr. VP1-2.2-ŠMM 07-K-01-023, finansavimo ir administravimo sutartis Nr. VP1-2.2-ŠMM-07-K-01-023.

Mokomojoje knygoje pateikti automobilių kelių asfaltinės dangos statybos technologijos procesų vertinimo ir valdymo originalūs metodai. Nagrinėjami veikiančių asfaltbetonio maišytuvų kokybės rodikliai ir jų svarbos nustatymo daugiatiksliai metodai. Taip pat pateikti asfaltbetonio maišytuvų atskirų įrenginių technologinių parametrų atitikties reikiamiems dydžiams nustatymo matematiniai modeliai. Apibūdintas šiuolaikių asfaltbetonio maišytuvų technologinių parametrų sureguliavimo algoritmas, jų baigiamojo dozavimo svorinių įrenginių tikslumo ir sklaidos parametrų statistinio skaičiavimo metodas. Uždavinių pabaigoje pateikti skaičiavimo pavyzdžiai. Leidinys skirtas technologijos mokslų transporto inžinerijos (03T) pagrindinių studijų studentams, studijuojantiems Kelių dangos tiesimo ir jų priežiūros technologijos modulį Leidinys parengtas ir išleistas už Europos struktūrinių fondų lėšas, jomis finansuojant VGTU Transporto inžinerijos, Biomechanikos ir Aviacinės mechanikos inžinerijos projektą „Studijų programų atnaujinimas pagal ES reikalavimus, gerinant studijų kokybę ir taikant inovatyvius studijų metodus“ pagal Lietuvos 2007–2013 m. Žmogiškųjų išteklių veiksmų programos 2 prioriteto „Mokymasis visą gyvenimą“ VP1-2.2-ŠMM-07-K priemonę „Studijų kokybės gerinimas, tarptautiškumo didinimas“. Projekto kodas Nr. VP1-2.2-ŠMM 07-K-01-023, finansavimo ir administravimo sutartis Nr. VP1-2.2-ŠMM-07-K-01-023.

Mokomojoje knygoje pateiktas praktinių užduočių rinkinys. Šie uždaviniai dažnai sutinkami, nagrinėjami ir sprendžiami automobilių ir geležinkelių transporto sektoriuose. Kiekviename leidinio skyrelyje pateikiama užduoties metodika, sprendimo pavyzdys ir savarankiško darbo užduotys. Leidinys skirtas technologijos mokslų srities transporto inžinerijos (03T) pagrindinių studijų studentams, studijuojantiems Transporto sistemos elementai modulį. Leidinys parengtas ir išleistas už Europos struktūrinių fondų lėšas, jomis finansuojant VGTU Transporto inžinerijos, Biomechanikos ir Aviacinės mechanikos inžinerijos projektą „Studijų programų atnaujinimas pagal ES reikalavimus, gerinant studijų kokybę ir taikant inovatyvius studijų metodus“ pagal Lietuvos 2007–2013 m. Žmogiškųjų išteklių veiksmų programos 2 prioriteto „Mokymasis visą gyvenimą“ VP1-2.2-ŠMM-07-K priemonę „Studijų kokybės gerinimas, tarptautiškumo didinimas“. Projekto kodas Nr. VP1-2.2-ŠMM 07-K-01-023, finansavimo ir administravimo sutartis Nr. VP1-2.2-ŠMM-07-K-01-023.

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.