Abstract: Emergency ability evaluation has a problem with the result conflict among the different evaluation methods, that is to say, the evaluation result of group decision depends on the evaluation method adopted. Emergency ability evaluation of accident occurred on expressway is studied in this paper. There have some problems that deserve some special consideration. Because the emergency rescue time gets tight, and road needs to be cleared as soon as possible, the index system of emergency ability evaluation in accident occurred on expressway should consider those factors. The evaluation method should deal with the linguistic information of expert evaluation. Furthermore, considering result differences among various evaluation methods, there has an optimization problem among various evaluation methods. A combination weight model of emergency ability evaluation is built, which is constituted of the linear combination of series of evaluation methods including 2-tuple linguistic AHP, G1 subjective weighting method, and 2-tuple linguistic entropy evaluation method, according to the minimum deviation principle. Along with the research idea of "the index system of emergency ability evaluation-various evaluation methods and corresponding combination weight model-case analysis", the paper mainly contains the following three parts. Firstly, the emergency ability in accident occurred on expressway is systematically analyzed and the index system of emergency ability evaluation in accident occurred on expressway is built based the idea of process management, Which includes the criterion layer with four first-level indexes and the index layer with 22 second-level indexes. Secondly, based on the linguistic assessment indexes, 2-tuple linguistic AHP, G1 subjective weighting method, and 2-tuple linguistic entropy evaluation method are used to compute the index weights, and then the linear programming model of combination weights with minimum deviation is built, which integrates above evaluating methods, to compute the optimal composite weight of the criterion layer. So the emergency ability evaluation value is obtained in accident occurred on expressway. Shanghai expressway emergency ability of "9·14" major road traffic accident is evaluated by the above model, and the different results derived from four evaluation methods are compared. In addition, the sensitivity analysis of evaluation indexes is discussed. Results show that the combination weight model with the minimum deviation principle achieves the maximum degree of consistency among different evaluation methods, and reduces "the polarization effect" of various evaluation methods in group decision, which can be applied into the field of emergency ability evaluation. The combination weight model with the minimum deviation principle can be not only applied to optimization problem among other various evaluation methods, but also other types of multiple attribute group decision making problems.

Key words: emergency ability evaluation, accident, minimum deviation, composite weight, multiple attribute group decision making problem, polarization effect