Dopravní stavby - Fakulta stavební - Vysoké učení technické v Brně

12th International Scientific Conference, April 20-22, 2009 Brno, Czech Republic 61In the second phase the individual criteria of the first degree were divided into more details andevaluated by significance or weight within the context of a given standpoint. The resulting divisionincluding the final evaluation of criteria significance on a second degree level of evaluation isshown in Table 2.Results evaluationThe resulting evaluation of the tested variant possibilities brought the following results. As themost suitable solution, from the viewpoint of benefits and risks of crash barriers at motorwayconstructions, is the variant using steel crash barriers. The second and the third order places in atight sequence were the variants using cable technologies and concrete crash barriers.From the result it is obvious that on the basis of an average evaluation in first order there wasplaced the variant non barriers, but for understandable reasons the spread of the total evaluation isvery (unacceptably) high (e.g. zero costs, but also zero absorption of impact power) and thereforethe use of a zero variant in a total evaluation of utility lapses to the last order place which does notguarantee requirements for the fulfilment of given aims. With other variant solutions there were notbrought about fundamental shifts, there was only increased the distance of the evaluation of steelcrash barriers from the following two possibilities.Tab. 3 Statistical evaluation of individual variantsVariantEvaluation Risk Developmentaverage value x spread σ 2 coefficient of skewness γ 1cable 6,030 2,402 -0,106steel 6,845 1,799 -0,501concrete 6,050 2,468 -0,040non barriers 6,902 5,590 -0,732Tab. 4 Resulting evaluation of individual variantsVariant Total profit (U) Order place in evaluationcable 5,101 2steel 6,276 1concrete 5,075 3non barriers 4,886 4Total benefit for a variant was calculated according to the relation:2U = x − σ 0.4 + y 0.3)( 1 )(1U is a total benefit, x is an average value, σ 2 is a spread and γ 1 is a coefficient of skewness.The negative skewness of the evaluation indicates, that the majority of evaluations for allvariants, was better than their average value. In the case of the evaluation of concrete crash barriersthe coefficient of skewness approaches zero and attests to the symmetrical evaluation of thisvariant.The resulting evaluation does not state an absolute result, but states the present situation, whichcan be further developed. Technical solutions (individual types of crash barriers) can be found inany further improved development simply on the basis of the gained evaluations. The authors of theresearch study consider the gained evaluations as the greatest added value to the stating of prioritiesin the order of technical variants.In the next elaboration it could be possible to investigate the critical amount of necessary effortfor removing narrow profiles in such a way as is shown in the evaluation.