RESEARCH, ANALYSIS AND EVALUATION OF ROUNDABOUTS CONSTRUCTED IN LITHUANIA

It was in the year 2001 when Lithuania first started constructing roundabouts on the rural roads of national significance with the heavyweight transit traffic and creating conditions for sustainably safe traffic. A data of statistical analysis shows that Lithuania aims at designing and constructing small roundabouts where the diameter of central island in most cases is higher than the average diameter of 25 m. Design and construction of roundabouts on Lithuanian roads often face the problem of territories. For this reason, the inner and outer radii as well as the entry and exit radii of roundabouts are minimum and do not meet the current requirements. Having studied, analyzed and assessed detail designs of roundabouts it could be stated that the structural defects could be caused not only by the deficiencies of some design standards or recommendations but also by the inaccurate use of current standards what results in taking improper design solutions and technological violations during construction of roundabouts and author and technical supervision create favourable conditions for the initiation of defects.