The demand for the Dongfeng Highway connecting Dongshi and Fengyuan, Taiwan, originates from a 7.3 ML earthquake disaster affecting residents' medical treatment and material transportation. The Dongfeng Highway route selection was identified as the socioscientific issues (SSI) and the Decision Factors Table and SageModeler (two representational modelling tools) were used to design a teaching module with two Generation-Evaluation-Modification modelling cycles. This study aims to explore the impacts of the Modelling-based SSI (M-SSI) teaching module on 23 preservice teachers' (PSTs) plans, factor dimensions, and quality of decision making. The results indicated that the PSTs focused on the original purpose of constructing the Dongfeng Highway; therefore, the Fengshi plan, which has advantages in safety, economy, and ecology, was chosen by most participants. Initially, PSTs focused only on 'relevance to the topic' factor and few relationships among other factors. However, they improved their decision quality by focusing on 'comparability and measurement' and 'sufficient evidence or justification' factors and more vertical relationships among factors after completing the module. Although the PSTs' horizontal relationships among factors still need to be strengthened, they demonstrated significant increases in factor, relationship, and overall scores with large effect sizes, indicating that the M-SSI teaching module can improve decision quality.