Detection model for unbalanced bidding in railway construction projects: Considering the risk of quantity variation

The application of a unit-price contract is nascent in railway construction projects in China. The investment risks for owners arising from unbalanced bidding in unit-price contracts should be given significant attention. Many models have been developed to help contractors place unbalanced bids, making the work of detecting unbalanced bidding even more difficult, especially the quantity error exploitation type of unbalanced bidding. Most detection models fail to consider the risks of quantity variation, a frequent occurrence in railway construction projects. Accordingly, this study developed a model for detecting unbalanced bidding based on an unascertained measurement theory and a analytic hierarchy process-fuzzy comprehensive evaluation method. The proposed model considers the risks in quantity variations. A hierarchical structure model was established to calculate the risks in quantity variations from different line items. A case study was presented to demonstrate the use of the proposed models for identifying and detecting quantity error exploitation unbalanced bids in railway construction projects. The model proposes a method for detecting the quantity error exploitation type of unbalanced bidding in railway construction projects, and can effectively improve accuracy without requiring a large amount of data from previous projects.