Abstract: In order to optimize the selection of bridge design scheme, an optimization model of bridge design scheme based on AHP-TOPSIS was established. The Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) was introduced into the model to optimize the selection of the bridge design scheme. Ten evaluation indicators were selected and the weights of the indicators were determined using Analytical Hierarchy Process (AHP) method to avoid shortcoming that the indicator weights were influenced by the subjectivity of the decision maker. The method improved the scientificalness and objectivity of indicator weights. This model was applied to evaluate four schemes of crossing bridge design. The comprehensive superiorities of the four schemes were calculated as: 62.5%, 74.6%, 18.1% and 64.6%. So the schemes were ranked as Y₂>Y₄>Y₁>Y₃, and scheme Y₂ was the optimal one. Scheme Y₂ was applied to bridge construction and good results were achieved.

Key words: road engineering, bridge design, optimization decision model, technique for order preference by similarity to an ideal solution (TOPSIS), analytic hierarchy process (AHP)