Tiesinių mišriųjų modelių taikymas kelio dangos savybių pakartotiniuose matavimuose

The data were collected by researchers at the Road Research Institute, in a study investigating the impact of differentfactors on road surface strength. In this statistical analysis, we apply linear mixed models (LMMs) to clustered longitudinal data, inwhich the units of analysis (points in the road) are nested within clusters (sample of four different road segments), and repeatedmeasures of road strength in these different points are collected over time with unequally spaced time intervals. The data arebalanced – each cluster has the same number of units, which are measured at the same number of time points. Because of correlateddata and different clusters in which data could be correlated, linear regression models are not appropriate here, and therefore linearmixed models are applied.Straipsnyje atlikta Vilniaus Gedimino Technikos universiteto Kelių tyrimo institute surinktų duomenų statistinė analizė, siekiant įvertinti įvairių veiksnių įtaką tiriamos kelio dangos laikomajai gebai. Matavimai atlikti keturiuose skirtinguose kelio ruožuose (klasteriuose), kuriuose laikomoji geba matuojama atskiruose dangos taškuose, ir matavimai tuose pačiuose taškuose kartojami skirtingais metais ir jų sezonais – turimi pakartotiniai matavimai, dėl kurių duomenys yra priklausomi. Priklausomumas gali atsirasti ir dėl klasterių, nes dėl tam tikrų, tik konkrečiam klasteriui būdingų savybių, taškai klasteryje gali būti priklausomi. Dėl šių priežasčių šioje statistinėje analizėje vietoje įprastų tiesinės regresijos modelių yra taikomi tiesiniai mišrieji modeliai (angl. Linear mixed model). Pastarieji leidžia įvertinti laikomosios gebos skirtumus ne tik tarp tam tikrų fiksuotų dangos savybių, bet ir atsižvelgti į kiekvieno klasterio ar į tyrimą įtraukto dangos taško klasteryje ypatumus bei pakartotinių matavimų priklausomumą

Evaluation of Asphalt Mix with Dolomite Aggregates for Wearing Layer

AbstractBearing capacity and durability of road pavement structure depends on design solution, transport loads, climate, materials and construction quality. But the main factors are selected materials for road pavement structure and their properties. Typically, there are selected high quality aggregates for asphalt wearing layer of heavy duty pavement. In Lithuania, granite aggregates are often used for asphalt wearing layer, but this magmatic rock is imported from other countries. Dolomite is one of the most available sedimentary rocks in Lithuania and quarries contain hundreds million tons of this material. Either, high quality dolomite is produced applying special extraction technology, and the mechanical properties of this material are similar to granite. The aim of this research is to evaluate high quality dolomite as aggregates for asphalt wearing layer and to design rut resistant asphalt mix with dolomite aggregates. Test results showed good bitumen-aggregate adhesion properties. There were designed asphalt concrete (AC) mixes using granite and high quality dolomite aggregates and stone mastic asphalt (SMA) mixes using high quality dolomite aggregates based on fundamental properties in accordance to standard EN 13108-1 and EN 13108-5. Resistance to permanent deformation of asphalt mixes is achieved by designing coarser gradation mixes with higher content of air voids (3–4%) comparing to traditional asphalt mixes for wearing layer (2–4%). Designed asphalt mixes were tested using empirical and performance based tests, which showed promising results for asphalt mixes with high quality dolomite aggregates

Performance of Soft Asphalt and Double Otta Seal within First Three Years

Gravel roads play an important role in the transport infrastructure. However, their maintenance (especially the control of dustiness using chemical dust suppressants) is expensive. Besides, the condition of gravel roads results in low driving comfort, longer travelling time, faster vehicle amortization, and so forth. Typically, these problems are solved by paving gravel roads with asphalt wearing layer. However, north countries practice had shown pavement structure high susceptibility to frost due to insufficient thickness of frost resistance layer. The construction of thicker frost resistant layer increases road construction cost by 25% and, in most cases, there is no need to increase bearing capacity by increasing total thickness of pavement structure. In 2012 19 gravel roads were constructed using cost effective rehabilitation technologies—soft asphalt and double Otta Seal in Lithuania. This paper focuses on those two technologies’ performance within first three years of constructed roads exploitation. The implemented experimental research consisted of three parts by evaluating constructed roads base layers bearing capacity; pavement roughness; and pavement distresses and defects. As a result, the acceptable performance indicators were determined for both technologies—soft asphalt and double Otta Seal. Also recommendations for construction and exploitation improvement were defined

Use of local aggregates in high modulus asphalt concrete layers

Povećanje intenziteta prometa uvjetuje izradu dugotrajnih kolničkih konstrukcija s vijekom trajanja od 20 do 40 godina. Sredstva koja su sada dostupna za održavanje i rekonstrukciju nisu dostatna za sprečavanje pojave kolotraga na postojećim cestama i ulicama s asfaltnom kolničkom konstrukcijom. Zbog tih se faktora istražuju novi materijali, mješavine i metode za izradu asfaltnih mješavina. Jedno od mogućih rješenja je i primjena asfaltbetona visokih modula. U radu su prikazana laboratorijska ispitivanja asfaltbetona visokih modula pri čemu su korištene razne vrste bitumenskih veziva i mineralnih agregata.High value of traffic flow influenced the need to build long lasting pavement structures with design life of more than 20–40 years. Current budget for maintenance and reconstruction is not sufficient for preventing the rutting on the existing asphalt pavement roads and streets. These factors lead to search for new materials, mixtures, and methods for preparation of asphalt mixes. The high modulus asphalt concrete is regarded as one of possible solutions. The laboratory study of the high modulus asphalt concrete with different types of bitumen binder and mineral aggregates is presented in the paper

Investigation into traffic flows on high intensity streets of Vilnius city

The measurements and analysis of traffic intensity were performed in the capital city – Vilnius, the largest urban area in Lithuania. Vilnius is a centre of business, industry and tourism, and therefore traffic intensity remains the highest in this part of the country. The intensity of vehicle traffic is not only generally calculated but also simultaneously classified which means is divided predefining vehicles into beforehand established categories. Data on traffic flows are used in a road maintenance program for calculating and assessing air pollution, ensuring traffic safety, regulating traffic flows etc. The article presents the methods for measuring traffic intensity which are and were used for calculating traffic intensity not only in the streets of Vilnius but also across Lithuania. Data on vehicle intensity and classification are collected either using technologies (loop and tube detectors, counters and video detectors) or expressing them visually. The article presents the dynamics of changes in the traffic volume on the roads of Lithuania for the period 2000–2009. Also, this article examines traffic intensity of all transport means, including trucks in the permanent traffic volume measuring stations that were installed near the roads in Vilnius zone (data on traffic for the period 2005–2009) and the streets of Vilnius city (data on traffic for the period 2007–2009). Data on traffic intensity were obtained by the Road Research Laboratory of the Road Department of Vilnius Gediminas Technical University in cooperation with the State Enterprise Transport and Road Research Institute (TRRI). First published online: 10 Feb 201

Traffic Calming Measures: An Evaluation of the Effect on Driving Speed

Road accidents are one of the leading causes of death in the world, particularly among young people. Excessive speed is one of the main risk factors in road traffic safety, increasing accident probability and affecting accident severity. Experimental research of the traffic calming measures allocation effect on the driving speed is presented in this paper. The research has been carried out on two aspects. The first one with respect to the mean speed and the second one regarding instantaneous speed. However, the paper is not only restricted by the above research. Standardized survey interview and questioning, a survey of public opinion, was carried out to find out the road users’ opinions about the need for traffic calming measures and speed control measures. Finally, the authors presented their insights and recommendations for the installation of speed humps and gateways and their optimum spacing.</p

Definition of concrete and composite precast concrete pavements texture

In the context of increasing traffic demands and emerging mobility trends road infrastructure has to shift towards the fifth generation of roads, which according to Forever Open Road (FOR) vision are envisioned as adaptable to traffic volumes, resilient to changing weather conditions, quickly built, effectively maintained, suitable for retrofitting, self-monitoring, self-repairing and recyclable. Concrete modular pavements can be defined as an example of such type of road infrastructure. Functional needs are mainly associated with implementation area/location, traffic and mobility demands, environmental constraints and etc. This also has a significant impact on the selection of Precast Concrete Pavements (PCP) texture formation method and materials. Concrete pavement surface texture affects both safety and tyre/road noise characteristics. Exposed Aggregate Concrete (EAC) and porous concrete are the most suitable noise reducing solutions for highways and streets wearing layer even in severe traffic and climate conditions. According to the literature analysis, the algorithm of highways and streets low noise concrete design was created. It is recommended to use the highest quality aggregates with maximum size up to 8 mm, gap-graded gradation, higher amount of cement and lower water/cement ratio. The most important characteristics of EAC are Mean Profile Depth (MPD), Mean Texture Depth (MTD) and profile count, while the most important characteristics of porous concrete are compressive strength, outflow and air void content

Laboratory study on the influence of casting on properties of ultra-high performance fibre reinforced concrete (UHPFRC) specimens

This paper presents a study on the effects of casting procedure and resulting fibre orientation on the properties of Ultra-High Performance Fibre Reinforced Concrete (UHPFRC). To investigate the impact of fibre orientation in the UHPFRC specimens, three approaches were employed. First, densities were measured from the top, middle and bottom zones of the cylinders to observe physical changes as the function of cylinder height. Secondly, two engineering fracture tests were performed in both compression and tension, and a comparison of fracture energies was conducted between different cylinder zones. While previous studies have explored the influence of steel fibres on the UHPFRC performance, the Semi-Circular Bending (SCB) and Disc Compact Tension (DCT) experimental setups have not yet been used in the UHPFRC fracture testing. Lastly, samples from different zones were scanned using X-ray computer tomography (X-ray CT). Both visual and digital image analysis of the X-ray scans were conducted in order to observe fibre orientation pattern changes within different zones. Although density calculations showed insignificant differences between different zones, fracture testing exhibited significant differences through the testing process as well as through fracture energy computations. Furthermore, X-ray CT demonstrated considerable differences in spatial fibre orientation with respect to two uniquely defined angles

Research of snow melting materials performance efficiency for road winter maintenance

In 2012, the Lithuanian Road Administration initiated a three-year research project ‘The study of effective winter road maintenance of national significance roads in Lithuania’. The main purpose of this research was to optimize road maintenance in winter and to determine the most effective means of combating slippery conditions. The research project was carried out by two institutions: the Road Research Institute of the Faculty of Environmental Engineering of Vilnius Gediminas Technical University and JSC ‘Problematika’. JSC ‘Problematika’ conducted exploratory experiments, which were divided into two phases. In the first phase of the experiment, five different snow melting materials (Slipperiness Reducing Materials – SRMs) were investigated in the laboratory. Different test methods were used in this investigation. In the second phase of the experiment, three SRMs with different properties were selected, and experimental road sections were set up to determine the road slipperiness and the change in coating layer thickness over time concerning different environmental conditions, as well as different snow and ice layer thicknesses. An optical remote sensor of Road Condition Monitor (RCM 411) was used for friction measurements on the roads. This report covers the laboratory test results of five different SRMs, road slipperiness measurement results using three selected SRMs and their analysis, comparison of the performance efficiency of the most widely used SRMs in Lithuania and the tested SRMs under different environmental conditions

Geotextile Selection Methods for the Lithuanian Road and Street Structures

This summary of the author’s PhD thesis supervised by Prof Dr Alfredas Laurinavičius and defended on 7 December 2007 at the Vilnius Gediminas Technical University. The thesis is written in Lithuanian and is available from the author upon request. In chapter 1 describes the existing problem, the need for the use of geotextiles for the separation of road and street structures. Also, the relevance of the research, the scientific novelty and originality of the dissertation, its aim and practical importance. Chapter 2 presents analysis of the geotextile selection methods for the separation of structural layers. In chapter 3 presented experimental research of the use of geotextiles for the separation of roads and streets pavement structure layers. Finally in chapter 4 the geotextile selection method for the use in the Lithuanian roads and streets pavement structures is presented. Developed geotextile selection method reflects the need for the use of geotextile, takes into consideration the factors having the impact on the occurrence of geotextile damages during pavement installation and in the course of road operation