## 2 Methodology
It begins with an analysis of various aspects of nD models, from creating structural components tailored to the project's specific levels of detail (LOD) to enhancing both accuracy and visualization ca  
Figure 1: Process of building the search query for identifying studies related to CIM implementation for transportation infrastructure. pabilities. Advanced visualization and constructability analyses are further explored using comparative analysis. Additionally, the operation and maintenance phase were divided into two separate research topics: _GeoBIM_ and _Asset Management_. This division was strategically employed to enhance the granularity of the analysis, facilitating a more detailed exploration of the technical challenges and advancements in the later stages of the infrastructure lifecycle. The _GeoBIM_ topic focuses on the advancement and challenges related to development of model-based workflow, while the _Asset Management_ topic investigates the practical challenges associated with information-management systems, emphasizing the integration of data and preservation of collected information across infrastructure lifecycle. This approach ensures a comprehensive evaluation across all critical phases, promoting a thorough understanding of CIM's application and its developmental trajectory in civil infrastructure. This thematic classification facilitated a detailed gap analysis and discussion, aiming to illuminate areas needing further investigation and to propose new directions for future research within the field. This structured approach ensures a comprehensive and organized review, promoting a clear understanding of the current landscape and research trajectories in CIM implementation. The five research topics with the abbreviations shown in parentheses are listed as follows:  
1. Application of advanced surveying methods to produce digital geospatial data (_Advanced Surveying_);
2. Geospatial analysis tools for project planning (_Geospatial Analysis_);
3. Multidimensional virtual design models (_nD Modeling_);
4. Integrated Geospatial and Building Information Modeling (_GeoBIM_);
5. Transportation infrastructure maintenance and rehabilitation planning (_Asset Management_). Figure 2: A flowchart representation of the review methodology. The proposed thematic research topics serve as the basis of this state-of-the-art review. The organization of this review paper is such that in the following sections of this paper, detailed discussions and research gap analyses is provided for each of these research topics with recommendations, as well as suggestions for future research. The cumulative number of CIM publications, as shown in Figure 3a, from 2015 to 2023 show a significant increase. Figure 3b reveals that publications related to \"_Asset Management_\", \"_GeoBIM_\", and \"_nD Modeling_\" constitute a combined 74 percent of the total collected CIM publications, indicating a noticeable trend within the industry towards adopting geo-enabled, model-based asset-management systems. This paradigm shift could be interpreted as the industry's willingness to move toward using a geo-enabled model-based asset-management system that facilitates the seamless integration of stored data across the complete lifecycle of transportation infrastructure. The increasing trend in the occurrence of CIM-related keywords within publications of recent years reflects the significance of applying modern tools and technologies throughout the lifecycle of transportation infrastructures. Based on the findings of this review study, detailed discussions on each of the five research topics identified in the literature review are now provided in the following sections of the paper. Table 1 represents a summary of the classification approach in the literature review in reference to the defined research topics.