标题： 影响水平建设项目变更令的因素：单价合同与总价合同的比较分析 显示英文标题

标题： Factors Influencing Change Orders in Horizontal Construction Projects: A Comparative Analysis of Unit Price and Lump Sum Contracts

摘要： 变更订单（COs）在建设项目中是常见现象，导致成本增加和工期延长。设计-投标-建造（DBB）项目受到州交通机构（STAs）的青睐，与其它项目交付方式相比，其变更订单出现频率更高。本研究旨在通过定量分析确定改进领域，以减少DBB项目中的变更订单频率。利用佛罗里达州交通部（FDOT）的历史招标数据，评估五个因素对特定水平施工项目的影响，即合同技术、项目地点、工作类型、项目规模和持续时间。使用离散选择模型评估了两种DBB合同技术，即单价（UP）和总价（LS）。对581个UP项目和189个LS项目的分析表明，在95%的置信水平下，项目规模、持续时间和工作类型对变更订单频率有统计学上的显著影响。离散选择模型在识别适合特定项目的合同类型方面相比STAs传统方法有显著改进。通过评估合同技术而非项目交付方式对水平施工项目的影响，可以提高DBB的使用效果，从而减少STAs的变更订单。 显示英文摘要

摘要： Change orders (COs) are a common occurrence in construction projects, leading to increased costs and extended durations. Design-Bid-Build (DBB) projects, favored by state transportation agencies (STAs), often experience a higher frequency of COs compared to other project delivery methods. This study aims to identify areas of improvement to reduce CO frequency in DBB projects through a quantitative analysis. Historical bidding data from the Florida Department of Transportation (FDOT) was utilized to evaluate five factors, contracting technique, project location, type of work, project size, and duration, on specific horizontal construction projects. Two DBB contracting techniques, Unit Price (UP) and Lump Sum (LS), were evaluated using a discrete choice model. The analysis of 581 UP and 189 LS projects revealed that project size, duration, and type of work had a statistically significant influence on the frequency of change orders at a 95% confidence level. The discrete choice model showed significant improvement in identifying the appropriate contract type for a specific project compared to traditional methods used by STAs. By evaluating the contracting technique instead of project delivery methods for horizontal construction projects, the use of DBB can be enhanced, leading to reduced change orders for STAs.