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).

Road guardrails of various types (made of reinforced concrete, cable and metal) are installed on the shoulders and traffic lanes of urban and suburban roads. Metal guardrails, consisting of Σ-shape and double T-shape metal posts and a protective W-shape horizontal beam, are the most popular. The deformation processes of the Σ-shape and double T-shape metal posts of the above-mentioned guardrails are examined. A mathematical model of Σ-shape (or double T-shape) metal post is developed. A metal post of Σ-shape (or double T-shape) is modeled, using one-dimensional firstorder finite elements, and taking into account elastic deformations, as well as the effect of soil on the buried post section of the guardrail. The deflections of Σ-shape and double T-shape metal posts caused by the impact of a motor vehicle moving at varying speed are determined.

The mathematical model of transport and pedestrian traffic restricting gate is designed. One section of the gate restricted the traffic of motor vehicles while the other limited the traffic of pedestrians. The gate was modelled based on the first‐order one‐dimensional finite elements taking into account only the resilience of the gate elements and the impact of soil on the ground‐embedded parts of the gate support and auxiliary posts. The potential deformations of gate elements were determined based on the mathematical model designed. The specific traffic event was investigated using the mathematical model of gate designed – four situations of motor vehicle–gate interaction were simulated and investigated.

Abstract. The paper deals with the interrelation between evaporation losses and automobile petrol quality and presents the results of research on modern petrol. It has been established that evaporation leads to an increase in heavy hydrocarbon concentration in petrol composition adversely affecting its quality and operational properties at the excess of permissible concentration.