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Recent Submissions

Now showing 1 - 5 of 15
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    Comparison of Unbound Granular Materials’ Resilient Moduli Determined by Cyclic Triaxial Test and Innovative FWD Device
    (MDPI, 2022-06-02) Stehlík, Dušan; Hýzl, Petr; Dašek, Ondřej; Mališ, Luděk; Kaděrka, Robert; Komenda, Radek; Sachr, Jiří; Veselý, Petr; Spies, Karel; Varaus, Michal
    Our study summarizes findings from a long-term monitoring of pavement on selected road sections with lower traffic intensity. The research involved the comparison of resilient moduli as a design parameter of unbound pavement base layers’ unbound granular materials (UGMs), determined in a laboratory by a test device for a cyclical triaxial test and in situ by impact load test using a falling weight deflectometer (FWD). In particular, the resilient moduli determined in the laboratory by a cyclic triaxial test (Mr,CTT) were compared with the real values of resilient moduli measured by FWD (Mr,FWD). A new, unique, and innovative FWD device was used to determine the Mr,FWD of the UGMs. The innovation lay in the dual-axis deflection measurement—measurement performed not just in the axis parallel to the road, but also in the axis in the transversal direction.
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    The Effect of Compaction Degree and Binder Content on Performance Properties of Asphalt Mixtures
    (Vilnius Gediminas Technical University, 2016-09-16) Hýzl, Petr; Dašek, Ondřej; Varaus, Michal; Stehlík, Dušan; Coufalík, Pavel; Dašková, Jaroslava; Coufalíková, Iva; Nekulová, Pavla
    The effect of compaction degree and binder content on performance properties of asphalt mixtures of an asphalt concrete type for wearing and binder courses are described in the paper. Measurements of stiffness modulus by two-point bending test on trapezoidal shaped specimens, fatigue characteristics, and resistance against frost cracking by thermal stress restrained specimen test have been performed on selected asphalt mixtures. The main aim of the experimental part was to determine to what extent the performance properties of the individual mixtures will be affected when decreasing the compaction degree by 3% in comparison to the optimal design, i.e. from 100% to 97% degree of compaction.
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    Verification and validation of a numerical model of fire and smoke development in a railway tunnel
    (Czech Technical University, 2016-01-01) Cábová, Kamila; Apeltauer, Jiří; Wald, František
    The paper describes the verification and validation of a numerical model of the development of fire and smoke in a railway tunnel carried out in the Fire Dynamic Simulator numerical code. To evaluate the correctness of a numerical solution of the model with respect to the mathematical model, the results are compared with a solution executed in the SmartFire numerical code. The influence of mesh size on the gas temperature results in the vicinity of the fire source is studied. The level of agreement between the numerical model and a physical model is validated by comparing the calculated data with data measured during a fire test in the Valik road tunnel in the Czech Republic.
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    Performance Characteristics of the Open-Graded Asphalt Concrete Filled with a Special Cement Grout
    (Vilnius Gediminas Technical University, 2015-12-14) Čiháčková, Pavlína; Hýzl, Petr; Stehlík, Dušan; Dašek, Ondřej; Šernas, Ovidijus; Vaitkus, Audrius
    This paper presents a performance of the open-graded asphalt concrete filled with a special cement grout in the road structures, introduces practical examples of the usage of this technology and defines the main properties. In addition, laboratory design of asphalt mixtures filled with special grout is researched. Finally, the results obtained from various laboratory tests are evaluated. The paper contains the open-graded asphalt concrete filled with a special cement grout mix design procedure and results of stiffness measurement, low temperature properties, permanent deformation and skid resistance. Open-graded asphalt concrete filled with a special cement grout mixture is compared to the commonly used asphalt mixes. The open-graded asphalt concrete filled with a special cement grout showed better results than the commonly used asphalt mixes by the stiffness and resistance to the permanent deformation characteristics but behavior at the low temperatures is slightly problematic.
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    Modernisation of Regional Roads Evaluated Using Ex-Post CBA
    (MDPI, 2021-02-08) Halámek, Petr; Matuszková, Radka; Radimský, Michal
    The aim of this evaluation is to verify the telling value of the Cost and Benefits Analysis (CBA) of regional roads modernisation based on an ex-post evaluation of the investments and their impacts on the incidence of traffic accidents. A set of 144 projects were the subject of evaluation. The analysis of the actual investment costs confirmed the assumption that the majority of projects were planned with a sufficient provision. When compared with the costs foreseen for the entire set of projects, the total reduction of actual costs spent was over 11%. The investigation of project impacts on traffic accidents was based on an analysis done prior to and after construction by using the Czech Police database. The measurement results show only minimum changes in the incidence of traffic accidents in the scenario prior to and after project completion. This however strongly contradicts the project goals declared, because the projects were anticipating almost zero accidents with a fatality and a 50% reduction of accidents with health consequences. However, a slight increase in road fatalities and in light and serious injuries was measured. These facts have a significant impact on the Net Present Value (NPV) and the weighted profitability index for the entire set of projects dropped from 16.7% to 2.8%. The key recommendation is to eliminate the impact on traffic accidents in the case of project evaluations processed ex-ante for projects focused only on a reconstruction or modernisation of existing roads.