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The speeding is a major road safety problem on the roads of Lithuania and many other countries. To reduce and control the speed of vehicles, engineering measures are installed on the roads of Lithuania and other countries – intelligent instantaneous and average speed enforcement systems, as well as many other engineering and structural speed reduction measures. The article presents good practices in the use of average speed enforcement systems, assessment of their effect on road safety. The article analyses the assessment results of the effect of the average speed enforcement systems installed on 25 sections of roads in Lithuania that have been operating for four years. Calculations of the effect factor of the installed average speed enforcement systems on road safety were performed using the before-and-after (B&A) method with a comparison group. Studies on the effect of application of speed control systems provide conditions for evaluating road safety, i.e., changes in road accidents linked to the effectiveness of implemented measures. The conclusions of the conducted study presented the calculations of the efficiency coefficients of the average speed enforcement systems on Lithuanian main and national roads. The analysis of the results of the conducted study allows stating that the installed average speed enforcement systems on 25 sections of Lithuanian roads increase overall road safety by 47%, reduce the number of collisions with animals by 80%, and the number of collisions with vehicles by 35%, as well as the number of other road accidents by 56%.

Properly designed and maintained asphalt pavements operate for ten to twenty-five years and have to be rehabilitated after that period. Cold in-place recycling has priority over all other rehabilitation methods since it is done without preheating and transportation of reclaimed asphalt pavement. Multiple researches on the performance of cold recycled mixtures have been done; however, it is unclear how the entire pavement structure (cold recycled asphalt pavement overlaid with asphalt mixture) performs depending on binding agents. The main objective of this research was to evaluate the performance of cold in-place recycled asphalt pavements considering binding agents (foamed bitumen in combination with cement or only cement) and figure out which binder leads to the best pavement performance. Three road sections rehabilitated in 2000, 2003, and 2005 were analysed. The performance of the entire pavement structure was evaluated in terms of the International Roughness Index, rut depth, and pavement surface distress in 2013 and 2017.

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

Average speed enforcement systems have been used on the roads of foreign countries for many years already, and give a positive effect on reducing accident number. The article presents good practices in the use of average speed enforcement systems in various countries and their impact on improving traffic safety. The article analyses the experience of system installation on the roads of Lithuania and the first results. The article also proposes methodologies for the selection of road sections to be enforced, the equipment used, and distribution of road sections in the road network of Lithuania. A detail analysis is given of the effect of average speed enforcement systems after their installation in three different periods on 25 road sections. The analysed data is differentiated between main and national roads. Conclusions and recommendations are given at the end of the paper for a future development of average speed enforcement systems.

However, for several decades, Europe has been witnessing demographic ageing. As a result of these changes, a more significant number of elderly road users will be involved in future traffic, and therefore safe mobility management of the older will become an increasingly important issue. Various physical, sensory, and cognitive constraints affecting elderly road users lead to a rise in the likelihood of an accident, which, due to the increased physical vulnerability, cause more serious consequences of road accidents. The findings reported by the authors of an in-depth analysis of accidents for four years have demonstrated that the risk of road fatalities for elderly road users is by one fifth more significant than the average of all age groups, and the pedestrian plays the most critical role in road traffic. To adequately compensate for the observed age-related physiological changes, the authors discuss actions and road safety measures to ensure appropriate conditions for older pedestrians on the streets.

Mechanical properties and slab dimensions of concrete are the major parameters based on which the performance of concrete pavement structures is predicted. Precast concrete pavement, as one of the most common modular pavement type, is the advanced next-generation technology characterised as high quality, durable, quickly built and easily maintained. The service conditions of precast concrete pavement (traffic loading and environmental effects) are similar to the conventional cast-in-place jointed plain concrete pavement. Thus, the precast concrete pavement structural design is similar to that of jointed plain concrete pavement. There are several concepts for the design of concrete pavement structure. However, they are based on different distress evaluation and critical stresses estimation methods assuming the slab dimensions that for jointed plain concrete pavement are within the wide joint spacing range from 3.5−6.0 m. The objective of this paper is to analytically evaluate the effect of concrete mixture mechanical properties on the thickness and dimensions of precast concrete pavement slab. Also, define the minimal thickness of precast concrete slab dependent on slab dimensions and concrete mixture mechanical properties elastic modulus and tensile splitting strength. The analysis is based on bearing capacity, performance and fatigue boundary conditions as reported by semi-probabilistic pavement design method Richtlinien für die rechnerische Dimensionierung von Betondecken im Oberbau von Verkehrsflächen RDO Beton 09. Considering that, concrete mixture has significant effects on pavement performance; the composition of concrete was also discussed in this paper. The optimal slab dimensions, concrete layer thickness, and base layer type is suggested in this paper. The outcomes of this analysis apply to the production of precast concrete pavement slabs.

Due to the increased traffic flow, more and more roadwork zones are formed in highways. Accidents are a significant problem in all European countries in roadwork zones while noncompliance with speed limits is one of the major safety concerns. Therefore roadwork zones are critical places from the point of traffic safety view where the possibility to get into an accident is increased. Roadwork zones introduce deviations from regular travel situations, and appropriate speed is needed to assure that the driver navigates safely through the roadwork zone. This research focuses on speed measurement in road work zones and attempts to evaluate the effectiveness of safety measures on speed limit compliance.

As the railway lifespan is the main criterion for selection of the aggregate for ballast and for planning the maintenance of the railroad, it is important to define the relationship between the particle load resistant characteristics and a lifetime of ballast in structure. Assessment of the quality of the ballast aggregate particles under dynamic and static loading reflect both, the toughness and hardness, and these are identified with the Los Angeles Abrasion and Micro-Deval Abrasion values. The model formerly developed by Canadian Pacific Railroads was adapted to predict possible loads expressed in cumulated tonnes. Different ballast aggregate mixtures were tested in the laboratory including dolomite and granite. Calculated potential gross tonnage (expressed in Million Gross Tonnes) of the railway per lifetime for each different aggregate type presented. The outcome of this research is established classification system of railway ballast aggregate and defined Los Angeles Abrasion and Micro-Deval Abrasion values of aggregate dependently on required lifetime.

Even though every layer of pavement structure is important and affects pavement performance, the asphalt layers visco-elasticity plays significant role. Bitumen properties, as well as asphalt mixture properties, vary depending on temperature and loading conditions. These variations influence entire pavement bearing capacity and has to be evaluated in pavement design. The main challenge is material behaviour description through simple models to incorporate them to pavement design. Generally, pavements are designed using Multilayer Elastic Theory assuming that all materials are elastic, isotropic, and homogenous. This paper presents analysis of two pavement structures response calculated according to three pavement design approaches. The dynamic modulus and phase angle of asphalt mixtures was estimated using Hirsch model after binder complex shear modulus tests. The visco-elastic behaviour was described with rheological Huet-Sayegh model and pavement responses estimation was done using MnLayer and ViscoRoute2 software. The analysis reviled static and dynamic load influence on pavement structure based on elastic and visco-elastic properties of asphalt layers. This allowed optimisation of layer thicknesses and determination of more cost beneficial pavement structure with appropriate performance.

Road transport is by far the most convenient way of transportation these days, offering the highest mobility and flexibility. While road transport is gaining popularity, the increased amount of traffic requires proper improvements and maintenance of the road network. The increasing usage of roads requires highest levels of maintenance of the road network. To ensure that, new methods with the ability of rapid, non-destructive monitoring and testing of the construction properties are on demand. Review and analysis of flexible road pavement testing means and methods are presented in this paper to introduce the problem and current technology. Complexity of these methods is pointed out. New approach to pavement testing using vibro-excitation and logarithmic decrement analysis of extinguishing free oscillations is proposed and its advantages are shown with application possibilities in a new advanced non-destructive pavement structure research device.

This summary of the author’s PhD thesis defended on 20 December 2012 at the Vilnius Gediminas Technical University. The thesis is written in Lithuanian and is available from the author upon request. Chapter 1 describes the analysis of road infrastructure safety management procedures and their implementation. Chapter 2 gives the overview of accident prediction models and the principles of their development. Chapter 3 presents the designed accident prediction algorithm for the roads of national significance of Lithuania, the developed mathematical accident prediction models for homogenous groups of roads and junctions, the implemented network safety ranking and the determined road sections with a potentially high accident concentration. Chapter 4 describes the testing and analysis of software intended for the implementation of accident prediction algorithm.

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

The Directive 2008/96/EC of the European Parliament and of the Council of 19 November 2008 on Road Infrastructure Safety Management requires that the Member States shall establish and implement the network safety ranking. Safety performance of existing roads should be increased by targeting investments to the highest accident concentration sections and (or) to the road sections or crossings with the highest accident reduction potential. Road network safety management is applied within the road network in operation covering the selection of traffic safety improvement measures in optimal locations, evaluation of the safety effects and implementing the measures. The article describes the method for selecting and prioritising road sections which have higher than the average accident saving potential in each road category. When selecting road sections for treatment, a potential reduction of accident costs shall be taken into consideration. Road sections in each category are studied and classified by the factors related to road safety, such as the number of accidents, traffic flow and road characteristics. The article describes how the procedure of the road network safety ranking and the ranking of high accident concentration sections is implemented in Lithuania and propose further steps.

Due to destructive factors (traffic loads, climatic and weather conditions, improper exploitation materials), bitumen properties irreversibly change in unservicable 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.

Analysis of the literature has shown that two main factors, which should be taking into consideration in designing of continuous bridges, are the influence of cracking on serviceability of the structures and inelastic behaviour of structural elements. Crack control is often the governing design criterion for the choice of the amount of longitudinal pre-stressing of reinforced concrete bridges as well as for the construction sequence of composite bridges. Present paper investigates cracking behaviour of reinforced concrete decks of continuous bridges over intermediate supports. It should be noted that this section behaves almost as pure tension ties. The paper presents results of complex investigation which has included experimental and numerical analyses of deformations and cracking resistance of reinforced concrete tensile members and a deck slab. Different techniques on crack controlling were analysed. Analysis was showed that the techniques worth predicting deformational behaviour of reinforced concrete members as well as assuring the cracking control in the bridge deck.

The falling weight deflectometer (FWD) is the device most commonly used for the measurement of strength of road pavement structure. Using this device the impact of the wheel of heavy vehicle to the pavement is imitated for the assessment of pavement strength. The stiffness of asphalt pavement layers, as well as E0 modulus values, measured using the FWD, strongly depend on the pavement temperature. When we use deflectometer for measuring asphalt pavement strength at different environmental conditions and in different season the values of E0 modulus should be reduced to the assumed standard temperature. During this research at the experimental asphalt pavement structure the temperature correction factor was revised. The use of this factor enables to reduce the values of the stiffness of asphalt pavement layers measured by the falling weight deflectometer to the standard temperature of +20 °C. In this way the influence of the temperature of asphalt pavement layers upon asphalt stiffness and E0 modulus could be evaluated.

Production of hot mix asphalt (HMA) requires a lot of consumption of energy, exhaustion of CO2 and other environment unfriendly materials. The fumes of HMA are injurious for roadmen and asphalt plant workers. The use of warm mix asphalt (WMA) allows reducing the HMA production temperatures at which the material is mixed and laid on the road. WMA helps to reduce the working temperature of asphalt up to 30 °C. This article presents the overview of different technologies of WMA production, advantages and disadvantages of these technologies. The laboratory research includes research of physical and mechanical properties of WMA produced with different technologies and different amount of additives for temperature lowering. Two different kinds of asphalt where tested in the laboratory. The chemical additives and chemical and natural zeolite were used for WMA production in the laboratory.

The rapid growth of heavy traffic, the increase in the standard axle load make scientists to look forward for new durable road constructing materials and their mixes. The continuously increasing need for strengthening the road pavement structures induces to use new road reconstruction technologies, to search for new methods in constructing pavement structural layers and investigate pavement structures under real conditions. The article presents construction of experimental pavement structures for the first time in the road history of Lithuania. The article also describes the installation process of stress and strain transducers in different layers of experimental pavement structures and initial results of stress and strain measurements. These measurements will be carried out each time after passed 20 000 ESAL’s calculated to 100 kN.

The paper deals with the performance of geotextiles separation function in road pavement structure and geotextile damage from transport loads. The experimental research consists of installation of two different types geotextiles on the bottom of the sub-base (gravel-granite mix, granite and dolomite) of road pavement structure with and without asphalt pavement. Throughout research evaluation of geotextiles damage and separation function performance depends on impact of different amount of vehicle loads has to be done. On stage I performance of separation function and geotextiles damage evaluated after 34 000 equivalent single axle loads (ESALs).

Practically all the road-related questions are solved with the consideration of climatic factors. Besides, the meteorological characteristics of the region, where the road objects are located, are taken into account, as well as their calculated values. This paper describes a methodology for determining these values. The examples are given on how to calculate the main meteorological characteristics of the percentage of integral probability, which are used in designing, constructing and maintaining roads.

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

The Lithuanian climatic conditions set high requirements for road and street maintenance in winter. In our country, the air temperature is below zero for 3–4 months per year. The longest period of this temperature is in eastern Lithuania, and the shortest period is in the coastal area. On average, the first snow cover forms from the middle of November and remains until the middle of March. Moreover, in winter thaws are frequent in Lithuania and the temperature fluctuates around zero. There is also high probability of glazed frost, freezing rain and fog. In most European countries road weather information systems have been established. The aim of these systems is to reduce the road maintenance costs in winter, to ensure good traffic safety, to inform drivers about poor traffic conditions. The following main components make up the integrated road weather information system: a) spatial analysis of the road microclimate to produce temperature graphs; b) road pavement and atmospheric characteristics’ sensors providing information on the actual weather conditions on the roads; c) computer and information network. The road engineer receives all information in a form which enables to use it quickly and take necessary actions. It also enables to collect external data on the weather conditions, which, upon its statistical analysis, can be used for road design, construction, repair and maintenance.

The article studies the problems of making the design solutions in the projects of gravel road reconstruction due to the taking of land for the right-of-way. The research was carried out during which the volume of taking the land due to the correction of the road plan and the costs of special planning related to taking land were forecasted for the gravel road sections under the supervision of the SE Telsil! regiono keliai. The article gives reccomendations on the necessity to correct the road plan and on the reduction of the related costs.

Road traffic safety has become a priority field in the integration process of the state road network into the European road network. Due to the Lithuanian integration into the economy of Western Europe, the state transport system has been rapidly changing. Road traffic safety has become one of the major factors describing the present transport system and its positive and negative changes. The article presents the road safety problems in Lithuania and gives an analysis of road accidents according to the data of the Traffic Police as well as their types and main causes. The analysis of the most important measures for improving traffic safety is presented. The second task is focused on the analysis of the methodology for calculating losses of accidents.

For the implementation of the Gravel Roads Paving Programme on the Lithuanian roads the reconstruction projects of the existing gravel roads are being prepared. This article studies the problems caused by taking the design solutions and correcting a longitudinal road profile of the objects included in the Gravel Roads Paving Programme. It also gives the results of investigating a longitudinal profile of gravel roads under the supervision of the State Enterprise Telsiai Regional Roads Administration. Based on investigation results, the design radii of vertical curves are suggested and recommended to use in projects for paving gravel roads.

Since 2000 the Equivalent Axle Loads on the main Lithuanian roads have increased twice. Deflections in asphalt concrete pavement, caused by the axle loads of the moving vehicles, is one of the essential causes of pavement degradation. Pavement deflections are widely measured by the Falling Weight Deflectometer (FWD), since, based on the measured deflection data, it is possible to calculate the deformation modulus of the whole pavement structure as well as separate structural layers. When designing pavement strengthening, values of the pavement deformation moduli are required, describing the weakest pavement condition. Today it is an urgent task to determine the effect of Lithuanian seasonal factors to the FWD-measured deflections in order to estimate the critical deformation modulus of the road pavement. According to the FWD-measured pavement deflections on the experimental road sections at a different time of the year the effect of seasonal factors was determined for the indices of structural strength of asphalt concrete pavements. Using the relationships of the effect of Lithuanian seasonal factors, determined by FWD measurements, it is possible to calculate the minimum indices of pavement structural strength.