Abstract. Statistical data on traffi c accidents in 2008 inLithuania is presented. Referring to statistical data, 'grounding on an obstacle' makes one-tenth of all registered traffi c accidents -9.4% (an obstacle may be a road guardrail, a lamp post, a tree, a bar, a gate, etc.). Road guardrails of various types are installed on the shoulders and dividing strips of urban and suburban roads. Th ey are as follows: reinforced concrete guardrails, cable guardrails and metal guardrails. Metal guardrails, consisting of Σ-shape metal posts and a protective W-shape horizontal beam, are most popular. Th e authors of the present paper examine the deformation processes of the elements of the above mentioned guardrail. A mathematical model of metal road guardrail was developed. Metal road guardrail was modelled using onedimensional fi rst-order fi nite elements, taking into account only elastic deformations, as well as the eff ect of soil on the buried post section of the guardrail. Based on the developed mathematical model of metal road guardrail, the defl ections of its elements caused by the impact of a vehicle moving at varying speed were determined. Th e obtained values of defl ections of guardrail elements (a protective W-shape horizontal beam and a Σ-shape post) presented in paper do not exceed the admissible values (of beam defl ections).

Abstract.A mathematical model of optimization problems in designing automobiles is suggested and requirements raised are defined taking into account the main technical and economic characteristics of the automobile. The optimality criterion of the integral parts of the automobile is presented. The system approach to the theory of parametric optimization based on generalized models is used and the algorithm for solving the considered problem is offered.

The main methods of frozen soil loosening are considered from the perspective of their effectiveness in transport‐related construction, and a new type of equipment is offered for earth‐moving in winter conditions.

The paper considers the general problems of optimization of parameters of a vehicle at the design stage. The approaches to the solution of the task are set out. The questions of a choice of the objective function and the system of limitations are in focus, as the problem of optimization makes sense, if there are several possible variants of its solution.Reference to this paper should be made as follows: Dyakov, I. 2013. The problems of optimal design in the automotive industry, Transport 28(3): 290Á294. http://dx.

The experiment was performed on 2 samples of the pig's cervical spine. 12 transpedicular screws were implanted using navigation templates. The safety and accuracy of installation of screws were evaluated by analyzing the results of computed tomography. 12 screws had a level of implantation safety of 0 degree – the screw was completely inside the bone structures of the vertebra. The accuracy of the implanted screws was evaluated by determining the degree of deviation of the obtained screw trajectory from the planned one. The resulting accuracy of the installed screws is 91 % and corresponds to class 1. At standard deviation, there were no significant differences in the axial and sagittal angles between the planned installation and the actual trajectory of the screw for the subaxial cervical spine on the left and right. There were no significant differences in the standard deviation in the axial projection at the points of entry and intended exit of the screw. Statistical analysis did not reveal significant differences between planned and actual results (P > 0.05).