Performance Measurement and Analysis of Building Information Modeling (BIM) Applications in the Railway Infrastructure Construction Phase

Abstract

Building information modeling (BIM) is acknowledged for enhancing efficiency and collaboration in the construction industry. However, its application in the construction phase of railway projects faces challenges. This study, utilizing quantitative and qualitative analyses, explores the advantage of BIM consulting services in the railway infrastructure projects. A comparative analysis of similar-scale projects shows that BIM significantly boosts construction efficiency, yielding a 197.6% economic benefit in pilot projects. This study also delves into the BIM application environment in railway construction. Our findings provide valuable insights into BIM’s advantages and challenges, emphasizing the need for further research. The results will contribute to advancing railway infrastructure and promoting BIM’s application, aiding decision makers and practitioners in understanding its potential contributions to a more efficient and sustainable industry.

1. Introduction

1.1. Background

Building information modeling (BIM) is a digital process involving the creation and management of a virtual model throughout the entire lifecycle of a construction or infrastructure project [1]. By sharing the model information, it significantly enhances work efficiency and enables collaborative management [2]. This is evident in stakeholders optimizing designs and construction processes through the visualization and simulation of construction processes, enabling the identification of potential issues [3,4]. Moreover, it facilitates communication and coordination among architects, engineers, contractors, and owners throughout the entire construction project [3]. Despite the proven advantages of BIM applications in various studies, there remain challenges in precisely measuring the details of BIM’s specific application’s environmental and economic benefits during the construction phase [5].

Several countries and organizations worldwide have developed BIM standards and guidelines to overcome challenges and promote BIM usage. For instance, the International Organization for Standardization (ISO) updated the global BIM standards in 2020 [6]. The UK has adopted three different levels of BIM standards [7], while countries like the United States, Finland, Norway, Singapore, and South Korea have issued their national BIM application standards to establish BIM working environments. These guidelines serve as blueprints for BIM implementation, assigning roles and responsibilities to various stakeholders. Despite widespread BIM applications in recent years [8], most of the literature analyzing BIM concentrates on architectural projects, with limited focus on infrastructure construction, building maintenance, and protection. In earlier publications [9], the authors explored the advantages of BIM applications in the design phase of the railway infrastructure, providing examples through quantitative research analyzing cost, work hours, and labor differences during the design phase. Additionally, qualitative research analyzed the primary tasks involved, offering insights into the application of BIM in the design phase of railway infrastructure.

However, due to higher demands on personnel, work hours, and costs during the construction phase when compared to the design phase, whether the use of BIM in the construction phase offers advantages in terms of cost and time savings is a question that this study attempts to address. Thus, to evaluate the performance of BIM applications during the construction phase of railway infrastructure projects. To achieve this, the authors conducted in-depth investigations and interviews, collecting data on the application of BIM during the construction phase from two ongoing railway infrastructure projects and the involved BIM consulting companies. Through data analysis, a quantitative assessment was performed by comparing the cost-effectiveness, work hours, and differences in the number of workers between situations where construction companies independently used BIM and cases where professional BIM consulting services were engaged. A qualitative analysis was conducted on the specific tasks, information data, location information, software used, and other aspects of BIM participation in the work, aiming to identify the specific advantages in terms of economic benefits gained from using BIM during the construction phase of railway infrastructure projects.

1.2. Research Review

To gain a comprehensive understanding of the advantages of BIM applications in railway construction projects, the authors conducted a literature review on the relevant research, with a particular focus on cost-effectiveness and studies involving practical case applications. Within our analysis of the Web of Science database (WoS) of the combination of “building information modeling (BIM)” (title) and “construction industry” (topic), there are 1076 article publications (Dec 29, 2023). The result distribution by country and region show there are 276 papers published in China (25.65%), 158 papers in England (14.68%), and 133 papers in the USA (12.36%); the publication of South Korea has 66 papers which make up 6.13% (Figure 1). We selected and analyzed some of the publications that related to BIM application in railway construction. On the other side, the publications of WoS by research area show that there are 714 (66.357%) papers in the engineering area were published, construction buildings have 393 papers set up by 35.524%, and business economics have 145 papers set up by 13.476% (Figure 2).

In these related publications, Sholeh, M. N. et al. proved that BIM applications could reduce 50% of time costs and reduce costs by 52.36% [10]. Azhar, S. et al. revealed the critical importance of accurate cost estimation and quantity surveying for effective budgeting and cost control in achieving cost benefits [11]. BIM application through collision detection allows for the early identification of design errors, ensuring timely issue resolution before construction. Due to technical staff checking for errors in advance, thereby reducing additional construction periods and saving costs in a railway subject. Thus, the integration of BIM into the rail industry is becoming a global trend [12]. Additionally, BIM contributes to construction planning and constructability analysis, enabling efficient project scheduling and construction process planning [13]. With BIM, the on-site validation, guidance, and tracking of construction activities become more straightforward, leading to increased productivity and quality control [14,15]. Shin, M. H. et al. emphasized the cost savings and project outcome improvements that implementing BIM in railway construction projects in the design phase may bring [16]. Moreover, BIM has gained recognition in multiple railway construction projects. For instance, Taiwan High-Speed Rail Corporation, in which BIM technology was used in the construction of the Changhua Station [17] and the Honam High-Speed Railway Lot No. 4-2 in Korea [18] successfully applied BIM in railway infrastructure construction [19].

These referenced studies delve into the application advantages of BIM in project construction, discussing how BIM supports the design, construction, and maintenance of railway construction projects, as well as how it yields economic benefits and cost savings. Integrating BIM into railway projects offers numerous advantages, including collaboration, time savings, cost optimization, conflict prevention in networks, facility management optimization, and enhanced engineering quality [12]. Leveraging BIM in railway construction projects empowers stakeholders to enhance decision-making processes, streamline project delivery, save costs, and enhance the overall efficiency of the industry [20].

2. Materials and Methods

Following is the methodology we used for this study, which is divided into two parts: qualitative research and quantitative research. In recent years, there have been plenty of publications on the effectiveness of BIM applications in the Web of Science, drawing significant attention from researchers. However, by searching WoS with topics “quantitative” and “railway”, there is only one publication result [16] that proved a lack of cost-effective quantitative research on the performance evaluation of BIM application in the field of railway infrastructure construction. Therefore, there is strong research significance in qualitatively and quantitatively studying the performance of BIM application environments [21,22,23]. Unlike previous studies, Ref. [16] which examined applications in the design phase, this study is about the construction phase. On the other hand, considering that railway construction projects typically involve longer durations, broader scopes of work, larger scales, and bureaucratic challenges compared to building projects, enterprises tend to retain traditional working environments. From this perspective, this study seeks to confirm the specific advantages of using BIM professional consulting in the railway construction industry and whether BIM consulting can offer better support for infrastructure construction projects in future BIM applications.

This study conducted a comparative analysis on two railway construction projects of similar scale to explore the advantages of BIM professional consulting services in the performance of the construction phase. However, for information security reasons, the report refers to these projects as “Project 1” and “Project 2”, as they are currently in the implementation phase. Both projects commenced simultaneously in July 2021. Project 1 spans 1.948 km, comprising two tunnels and three bridges, while Project 2 spans 2.810 km, including one tunnel and one overpass bridge.

Due to the extended duration of the construction projects, data collection for this measurement study spanned ten months. Quantitative data were collected by BIM consulting companies and construction enterprises. Separately, the project manager collects data based on the questions in the monthly project plan and quantitative template and provides it to the researcher each month, while qualitative data were obtained through in-depth interviews and surveys conducted by researchers with the construction project manager, BIM consulting company manager, and technical personnel. The researcher conducted in-depth interviews with engineers who were actually involved in the construction of the project according to the questions in the qualitative survey template, which consisted of a total of three interviews that lasted a total of ten months (the first month, the fifth month, and the tenth month). The number of interviews was based on twenty people. To ensure the objectivity of the data, the researchers were conducted anonymously in groups of three to the engineers involved in Project 1 and Project 2, respectively.

Measurement Template

In order to showcase the comprehensiveness of the research project, the researchers designed a survey template addressing both qualitative and quantitative analysis questions. The measurement template was crafted to cover aspects such as BIM deliverables, project duration, quality assessment, labor costs, BIM human capital, BIM investment factors, etc. Through in-depth interviews and discussions with BIM consulting companies and construction enterprise managers, the measurement template was refined and finalized. Quantitative measurement questions were categorized into 7 groups, comprising 16 aspects and a total of 21 questions. Qualitative measurement questions were organized into 4 groups, covering 8 aspects and a total of 15 questions. These questions cover personal information of the respondents, their BIM experience, salary levels, work-related details, and other relevant aspects (

Table 1. Measurement survey template.

Quantitative Measurement
Categories		Area of Questions	Code
	4D Simulation of Construction Information 1	Cost of Building Collaborative Environment	a
		Cost of Initial Clash Checks 3	b
		Cost of Shop Drawing Information Work	c
		Cost of Coordinating and Resolving Other Issues	d
	5D Simulation of Cost Estimation 2	Labor Costs	e
	BIM Coordination in Construction Projects	Costs of Resolving Clashes and Preventing Delays	f
		Rework Costs Incurred due to Design Changes and Errors	g
		Risks Costs Arising from Design Errors	h
		Costs of Rebuilding after Rework	i
		Costs of Preventive Measures for Rework	j
	Organizational Human Resources	Costs of BIM-Related Support Department Involvement	k
	BIM Investment Costs	Software and Hardware Procurement	l
		Software and Hardware Upgrades and Maintenance	m
	Creating BIM Models from 2D Drawings	Costs of Quantity and Drawing Preparation	n
		Operational Costs in Case of Data Loss	o
	BIM Training	Employee Skill Development and BIM Training	p
Qualitative Measurement
Categories		Area of Questions
BIM Implementation Overview		4D Simulation for Construction Sequencing History of Construction Projects with BIM Implementation Support for BIM Implementation
Team and Personnel		Team Members’ Experience Team Composition and Role Allocation
Financial Aspects		Investment for BIM Implementation
Impact Assessment		Benefits of BIM Adoption Effects of BIM Application

¹ The 4D BIM is the process of using 3D models combined with time and schedule-related information such as programs, site surveys, and logistics models to create a virtual construction sequence. ² The 5D BIM dimension integrates the information further with cost data by bringing detailed cost information into the project. These cost data may include schedules, prices, and quantities. ³ Clash issues refer to spatial collisions and conflicts occurring between structural components and various specialty equipment pipelines during the construction process.

and

Table 2. Measurement survey questions.

Quantitative Element Survey Questions
Categories	Questions
4D Simulation of Construction Information	How many people are involved, and what are the costs for establishing a collaborative working environment?
	What are the costs associated with clash detection during the 3D model construction process?
	How much time and cost are involved in meetings for adjustments in case of changes or additional issues?
	What are the costs for adding information and editing work for Shop Drawings?
5D Simulation of Cost Estimation	What are the costs associated with the extraction and modification of quantity information for each component based on the Level of Development (LOD) of the 3D model?
BIM Coordination in Construction Projects	What is the cost of resolving clashes and preventing air delays on the construction site?
	In the construction process, what are the costs associated with design changes and errors that result in rework?
	How much do delays in time and costs occur due to the resolution of design errors?
	What are the costs associated with demolition and additional work due to on-site construction issues?
	Evaluation of BIM contribution for each Request for Information (RFI) using the Likert scale: -Can be confirmed without BIM application -Can be confirmed without BIM application but -meaningful -Average -Difficult to confirm without BIM application -Difficult to confirm without BIM application and results in rework
	What is the cost of original construction for each RFI?
	For BIM operation, what is the labor cost for personnel deployed by the construction company for BIM management?
Organizational Human Resources	How many personnel are in the BIM department?
	What is the ratio of BIM department personnel to the total number of personnel?
	How does the labor cost in the BIM department compare to other departments?
BIM Investment Costs	What is the unavoidable initial investment cost in the early stages of BIM implementation?
	What are the maintenance costs for BIM software and hardware?
Creating BIM Models from 2D Drawings	What is the cost associated with the Level of Development (LOD) of drawings for each trade?
	How much does it cost to quantify from the BIM model?
	What is the manpower and time investment for rework due to common format conversion for data sharing?
BIM Training	If separate BIM personnel training is conducted, what is the training frequency and cost?
Qualitative Element Survey Questions
Area of Questions	Questions
4D Simulation for Construction Sequencing	How do you primarily use BIM in your work?
	How is data classified when requesting BIM information?
	What is the purpose when requesting BIM information?
	How is the requested BIM information data utilized?
	What types of information are utilized in responding to BIM RFI data?
	In what form is the information utilized in responding to BIM RFI data?
History of Construction Projects with BIM Implementation	How many BIM technicians were involved in previous projects that utilized BIM?
Team Members’ Experience	What is the rank and salary of BIM technicians in your company?
Team Composition and Role Allocation	How is the role distribution and ratio of team members in your team?
Support for BIM Implementation	What support measures exist at the government level to enhance the use of BIM?
	What support measures exist at the company level to enhance the use of BIM?
	Does your company have plans for workshops or support to enhance understanding and expertise in BIM?
Investment for BIM Implementation	What software do you use when employing BIM?
Benefits of BIM Adoption	Are there advantages obtained by using BIM compared to the methods employed before BIM implementation?
Effects of BIM Application	Are there areas of improvement identified by applying BIM during the construction phase compared to not using BIM?

Note: The two project sites will be surveyed using the same set of questions.

).

According to the quantitative measurement template, the authors devised formulas for quantitative measurements during the construction phase, as illustrated in

Table 3. Quantitative measurement calculation formulae.

Area of Questions	Calculation Formula	Code
Cost of Building Collaborative Environment	Average Labor Cost per Rank × Number of Workers × Working days + Other Expenses 1	a
Cost of Initial Clash Checks		b
Cost of Shop Drawing Information Work		c
Cost of Coordinating and Resolving Other Issues		d
Labor Costs		e
Costs of Resolving Clashes and Preventing Delays		f
Rework Costs Incurred due to Design Changes and Errors		g
Risks Costs Arising from Design Errors		h
Costs of Rebuilding after Rework	Average labor cost per rank × Number of workers × Working days + Material cost + Other expenses	i
Costs of Preventive Measures for Rework	Average labor cost per rank × Number of workers × Working days + Other expenses + Service fee	j
Costs of BIM-Related Support Department Involvement	Average labor cost per BIM department × Total number of employees	k
Software and Hardware Procurement	BIM software acquisition cost + BIM hardware acquisition cost	l
Software and Hardware Upgrades and Maintenance	BIM software maintenance cost + BIM hardware maintenance cost	m
Costs of Quantity and Drawing Preparation	Average labor cost per rank × Number of workers × Working days + Other expenses	n
Operational Costs in Case of Data Loss		o
Employee Skill Development and BIM Training	Training cost × Number of training sessions	p

¹ Other expenses: According to the state regulations should be paid in the project construction investment and included in the cost. Such as management fees, subsidies, transport costs, taxes, etc.

. Data for this section will be recorded by the construction unit and professional BIM consulting companies during the construction process. Considering the unique nature of construction phase projects and assuming other costs, such as materials and equipment, remain constant, the most influential factors on costs are delays in project duration and labor costs. Therefore, cost calculations primarily involve three fundamental values: (a) base costs; (b) labor costs based on different skill levels; and (c) working days. It is worth noting that some factors among these, irrespective of BIM participation, have a minimal impact on performance calculation results. Examples include rework and rebuilding costs, rework prevention costs, BIM training, BIM support, and BIM investment.

3. Analysis and Results

3.1. Quantitative Analysis

3.1.1. Comparative Analysis of Investment Cost

Although questions involving 16 areas were designed for quantitative research when the researchers developed the quantitative research template. However, in analyzing the results, it was found that there were some data virtually unchanged with or without the involvement of a professional BIM consultancy (e.g., code a–d), or had very little impact (e.g., code k–p). In addition, because railway engineering construction is a large and complex project, this process involves a very complicated amount of work; in order to simplify the calculation, we assume that all other conditions are fixed situation, selected the three aspects of the greatest impact on the project investment to measure the comparison (e–g).

The cost-effectiveness of BIM in the construction phase primarily manifests in labor costs and construction duration. With the intervention of BIM information, it becomes possible to proactively prevent common occurrences in the construction process, such as clashes, design inconsistencies, or other issues leading to design changes. This proactive approach helps reduce construction duration and lower costs. However, it is crucial to note that rework caused by issues like substandard construction quality is something BIM cannot entirely prevent. To conduct a comprehensive cross-sectional analysis of the impact on cost-effectiveness between the involvement of professional BIM consulting services and the use of BIM by construction companies themselves, the quantitative survey focuses on factors that significantly affect economic benefits under professional BIM consulting involvement. Factors with relatively minor impacts, such as BIM training costs and BIM investment costs, are excluded from the analysis. For clarity in the following discussion, “BIM” will represent the scenario where professional consulting services are involved, while “Non-BIM” will represent situations where construction companies use BIM on their own. During data collection, professional BIM consulting companies and construction companies selected similar-scale work content from Project 1 and Project 2 for measurement.

On the other hand, some literature indicates that BIM technology has not been widely disseminated and applied in the South Korean construction industry, particularly in construction projects [24]. On-site construction management personnel still exhibit hesitation toward adopting BIM technology [25]. This observation was confirmed through in-depth interviews with BIM consulting companies and management personnel from construction companies. Presently, the practical application of BIM in South Korean construction projects is primarily limited to the design phase. Due to technological imperfections and a lack of experience, a significant gap exists in the actual application of BIM for most construction companies. Therefore, the focus of this quantitative analysis is primarily on (e) labor costs; (f) costs of resolving clashes and preventing delay; and (g) rework costs incurred due to design changes and errors. These aspects are considered critical areas that require special attention in the application of BIM during the construction phase.

In the case of rework resulting from design changes and errors, it involves modifying existing models and adding detailed models. Labor costs are composed of the quantity of labor and the corresponding work details on the construction site, reviewed by on-site construction management. Regarding the costs associated with resolving clashes and preventing construction delays, this includes measures such as proactively addressing clash issues and preventing delays in the construction schedule. These measures involve creating and simulating safety-integrated models, updating data, and similar actions.

According to

Table 4. Comparative measurement cost between participation in BIM consultancy and non-BIM participation.

BIM Task Categories	Code	Descriptions	Non-BIM (Unit: USD)		BIM (Unit: USD)
			Project 1	Project 2	Project 1	Project 2
5D Simulation of Cost Estimation	e	Labor Costs	61,976	51,646	12,395	17,600
BIM Coordination in Construction Projects	f	Costs of Resolving Clashes and Preventing Delays	45,965	24,445	30,643	15,838
	g	Rework Costs Incurred due to Design Changes and Errors	37,185	66,623	24,790	44,415
Total			145,126	142,714	67,828	77,853
Average total cost			143,920		72,840

Note: The measured amount, converted to US dollars based on real-time exchange rates, may incur discrepancies.

, in the investigation of labor costs, it was found that, with the participation of professional BIM consulting, the labor costs in Project 1 were USD 12,395, and in Project 2, they were USD 17,600. Without BIM consulting, the labor costs were USD 61,976 and USD 51,646, respectively. Regarding the cost of resolving collision issues and preventing delays, during the BIM consulting period, the construction cost for Project 1 was USD 30,643, and for Project 2, it was USD 15,838. The costs without BIM consulting were USD 45,965 and USD 24,445, respectively, which was significantly higher than the working environment with the participation of professional BIM consulting.

In terms of rework when design changes and errors occur, the rework costs for projects 1 and 2 with BIM consulting were USD 24,790 and USD 44,415, respectively. The costs without BIM consulting were USD 37,185 and USD 66,623, significantly higher than the construction costs for contractors using BIM. For performance measurement analysis, in “Cost Measurement with BIM Consulting,” each cost is defined as an investment cost in the construction phase. In “Cost Measurement by Contractors,” each cost is defined as a basic cost in the construction phase. The percentage increase in costs can be calculated by dividing basic costs by investment costs.

As shown in

Table 5. Comparative analysis of investment cost percentage.

Title	Division	Cost	Percentage (%)
Project 1	Basic Cost	145,126	214.0
	Investment Cost	67,828
Project 2	Basic Cost	142,714	183.3
	Investment Cost	77,853
Average total cost	Basic Cost	143,920	197.6
	Investment Cost	72,840

, the investment percentage for Project 1 is 214.0%, resulting in a cost efficiency improvement of 114.0%. For Project 2, the percentage is 183.3%, leading to an 83.3% improvement in cost efficiency. In terms of the average total costs, with the participation of a BIM consulting company, the calculated average investment cost in the construction phase is approximately USD 72,840, including labor costs, costs of resolving collision issues and preventing delays, and rework costs when design changes and errors occur. On average, if constructed solely by contractors, the average basic cost in the construction phase is approximately USD 143,920. When a professional BIM consulting company is involved, the average total investment cost percentage is 197.6%, resulting in a cost efficiency improvement of about 97.6%.

3.1.2. Comparative Analysis of Working Days and Worker Numbers

To further understand the impact of BIM applications on labor quantity and construction time,

Table 6. Difference in worker numbers and working days between using BIM and non-BIM.

Code	Non-BIM				BIM
	Project 1		Project 2		Project 1		Project 2
	Worker Numbers	Working Days	Worker Numbers	Working Days	Worker Numbers	Working Days	Worker Numbers	Working Days
e	2	120	2	100	3	24	5	18
f	17	48	9	46	—	—	—	—
g	12	29	14	61	—	—	—	—
Total	31	197	25	207	32	101	28	125
Average of total workers	28 people				30 people
Average of working days	202 days				113 days

Note: Worker numbers are calculated per working day.

compares the changes in the number of workers and working days between scenarios with and without the participation of professional BIM consulting. These data are collected from measurements conducted separately by the construction units and BIM consulting units of the two projects. For readability, unchanged data are represented by “—”.

The results indicate that, in terms of the number of workers, the scenarios of addressing collision issues, preventing delays, and rework costs due to design changes and errors did not result in changes, regardless of the participation of professional BIM consulting companies. However, with the involvement of BIM consulting, the number of workers increased by one person and three persons at the two construction sites (from two to three persons and from two to five persons, respectively). Although the number of construction personnel increased when compared to self-construction by the construction units, the total working days at the two sites reduced from 120 days to 24 days and from 100 days to 18 days, respectively.

Comparing the data from the two construction sites, the total number of workers slightly increased when BIM consulting was involved, from 31 to 32 persons for Project 1, and from 25 to 28 persons for Project 2. The average total number of workers also slightly increased from 28 to 30 persons. However, the total working days at the construction site of Project 1 rapidly decreased by 96 days, from 197 days to 101 days, and the construction site of Project 2 also reduced by 82 days, from 207 days to 125 days. The average total days decreased significantly from 202 days to 113 days, a reduction of 89 days. This indicates that the involvement of BIM consulting companies, while increasing the average number of workers, effectively shortens the working time, thereby reducing the overall investment cost of construction projects.

3.2. Qualitative Analysis

Based on the qualitative survey questions, we have organized our survey results into the following areas.

3.2.1. The Content of Work and Time Spent on BIM Usage

To understand the content of using BIM, the researchers collected information on the tasks involved in the construction phase BIM participation and the time spent on BIM. These tasks were detailed into additional detailed modeling, constructability review, process management, construction cost management, and site management. A total of 379 work items were collected from Project 1, and 410 work items were collected from Project 2 (

Table 7. The content of work and time spent on BIM usage.

Project	Work Item	Count	Percentage (%)	Time	Percentage (%)
Project 1	Additional Detailed Modeling	173	45.65	675.5	46.30
	Constructability Review	50	13.19	173.5	11.89
	Process Management	41	10.82	127.5	8.74
	Construction Costs Management	67	17.68	365.5	25.05
	On-Site Management	48	12.66	117	8.02
	Total	379	100.00	1459.00	100.00
Project 2	Additional Detailed Modeling	205	50.00	860.2	52.35
	Constructability Review	19	4.63	56.0	3.41
	Process Management	83	20.24	353.4	21.51
	Construction Costs Management	55	13.41	243.0	14.79
	On-Site Management	48	11.71	130.5	7.94
	Total	410	100.00	1643.10	100.00

).

The results show that, in terms of the content of BIM work, Project 1 had a higher number of additional detailed modeling tasks (173 items), accounting for 45.65% of all work, followed by construction cost management (67 items), and the least was process management (41 items). Similarly, in Project 2, the highest number of tasks was related to additional detailed modeling (205 items), accounting for 52.35%, followed by process management (83 items), and the least was constructability review (19 items). In terms of time spent, Project 1 invested the most time in additional detailed modeling (675.5 h), accounting for 46.30% of all work. Process management and site management took the least time, constituting only about 8% of the total work time. Similarly, Project 2 spent the most time on additional detailed modeling (860.2 h), accounting for 52.35% of all work. The least time was spent on constructability review (56 h), representing only 3.41% of the total work time.

Therefore, it can be observed that in the specific tasks of BIM applications in the construction phase of railway projects, the main focus is on additional detailed modeling, which nearly constitutes half of all BIM work and is also the most time-consuming part of the work.

3.2.2. Categories by Location Information

During the measurement phase of the pilot project, researchers investigated the location information and work proportions of the issues handled by BIM (Figure 3). Apart from uncategorized information, the issues in Project 1 were, in order, tunnel (21.90%), construction road (5.01%), and existing structure (2.64%). In Project 2, the issues were, in order, tunnel (58.05%), underground passage (6.83%), and existing structure (6.10%). Therefore, it can be observed that in the construction phase of railway projects applying BIM, the most commonly addressed issues are related to tunnels.

3.2.3. Detail Information of BIM

Based on the historical data of on-site BIM-related work, detailed information was classified, and its weight throughout the entire process was examined. In Project 1, the main issues addressed by BIM were modeling (33.25%), followed by quantity verification (17.68%) and modeling materials (10.29%) (Figure 4). Similarly, in Project 2, the primary issues were modeling (35.61%), followed by quantity verification (13.41%) and process schedules (9.76%). Therefore, in both construction projects, tasks related to modeling constitute the largest proportion of BIM-related work.

3.2.4. Usage of BIM Software

Researchers categorized the software used in experimental on-site work and examined its proportion throughout the entire process. The top three applications used in Project 1 were Revit (45.12%), Navisworks (26.76%), and Excel (12.30%) (Figure 5). These applications were utilized for additional detailed modeling, construction feasibility reviews, process management, cost management, and on-site management tasks.

In Project 2, the predominant BIM software was Revit, accounting for 53.45%, followed by Navisworks (13.78%) and AutoCAD (13.59%). Overall, Revit emerged as the most commonly used BIM application in construction projects, likely due to its primary association with modeling tasks in the field of architectural engineering.

3.2.5. Effects of BIM Application

Researchers conducted in-depth interviews to investigate the effectiveness of BIM applications in solving problems based on work content categories during the pilot work at the construction site. For further detailed modeling, precise quantities could be calculated, and model quality could be improved through thorough inspections of individual objects, enabling comprehensive material management. In the process of construction feasibility reviews, errors could be identified to enhance the accuracy of information, and stability reviews could identify the risk areas, leading to design changes as required by the data. During process management, issues could be easily seen by others due to information sharing, promoting interdisciplinary communication. Task history records facilitated monthly manpower checks (M/M). When calculating quantity data, comparing and reviewing construction cost management tasks allowed for sharing the work status with the headquarters, enabling on-site managers to inspect monthly work progress and visually confirm the 4D construction status of each process (

Table 8. Effects of working on pilot site application BIM.

Item	Effect
Additional Detailed Modeling	Accurate quantities when reviewing quantities. Through object separation, each object can be checked in detail. Improve quality with detailed revisions and reviews, including interference and dimensions between each structure. Consolidate materials that were previously in different files.
Constructability Review	Improve information accuracy by finding and correcting errors. Verify processes through simulation. View details of work. Identify risk zones in design stability reviews. request design changes based on data.
Process Management	The construction process can be checked in 4D. Check M/M by task history. Easier to see issues and communicate with each other. Aggregate files and simulate processes with Navisworks. Simulation work is smooth by entering the code in the same way as the process and CSV.
Construction Costs Management	Verification is possible when calculating quantity data. It is possible to compare and review design quantity and BIM quantity.
On-Site Management	Share headquarters work status. Visual confirmation is possible through 4D construction for each process. Smooth confirmation of monthly work performance Increase the accuracy and granularity of BIM, making it more usable and efficient.

).

4. Discussion

This analysis of investment costs in this study primarily focused on labor costs and rework costs, overlooking other critical aspects within the comprehensive and intricate processes of the construction phase. The intricacies of the construction phase encompass various factors, including material costs, construction machinery and equipment costs, construction network scheduling, process management, construction quality management, safety management, and operation and maintenance. These factors play a pivotal role throughout the construction process, significantly influencing the cost-effectiveness of the project.

Material costs represent a significant component of the construction phase, directly impacting the economic and sustainable aspects of the project. The application of BIM can optimize material selection and management, enhance material utilization, and reduce waste, ultimately leading to a reduction in material costs [26]. Additionally, the simulation and optimization of construction machinery and equipment through BIM technology can effectively lower equipment costs and improve construction efficiency [27].

Construction network scheduling plays a crucial role in project success, and the utilization of BIM in this aspect is expected to enhance the visualization and planning capabilities of the construction process. This improvement makes tasks clearer and more controllable, thereby reducing delays and improving schedule efficiency. Process management, construction quality management, and safety management are equally vital aspects of the construction phase that cannot be overlooked [28]. The application of BIM, through real-time monitoring and simulation, has the potential to elevate management levels, mitigate potential risks, and ensure the quality and safety of the project. This area provides a compelling avenue for future research into the application of BIM in the construction phase.

Furthermore, exploring the application of BIM in operation and maintenance during the construction phase is a noteworthy direction. By establishing a comprehensive information model during the construction phase, post-project delivery can be more effectively managed for operation and maintenance, achieving full lifecycle management [29]. This approach can lead to a reduction in operating costs and an extension of the facility’s lifespan.

However, in the current research, these factors have not been adequately addressed, potentially oversimplifying the application of BIM in the construction phase. Therefore, to enhance the level of BIM implementation in the construction phase in South Korea, there is a need to bolster training and technical support to improve the BIM skills of industry professionals. Only by augmenting the practical application capabilities of BIM on construction sites can the full potential advantages of BIM throughout the entire lifecycle of construction projects be comprehensively realized, resulting in more significant economic benefits. This also underscores the necessity for a more in-depth and comprehensive exploration of the promotion and practical application of BIM in the construction phase within the South Korean construction industry in the future. In addition, the construction projects involved in BIM will generate a large amount of data due to a large number of model modifications, and how to efficiently process the data, share the data, and store the data is also a great challenge in the practical application of BIM.

In summary, although this study has addressed the aspect of investment costs, the complexity of the construction phase presents broader and deeper challenges to the application of BIM. Future research should adopt a more comprehensive approach, taking into account various factors, to explore the full potential advantages of BIM in the construction phase and propose corresponding solutions. This effort aims to facilitate a more comprehensive and in-depth application of BIM in the construction industry in South Korea and globally. Long-term attention and thorough research in this field will contribute to continually refining the application of BIM technology in the construction phase, providing more reliable support for the sustainable development of the construction industry.

5. Conclusions

This study, building upon previous research on performance measurement methods for BIM projects both domestically and internationally, developed a performance measurement survey template for the construction phase of railway construction projects based on quantifiable performance measurement factors (BIM deliverables, duration, quality assessment, labor costs, BIM human capital, and BIM investment factors). The quantitative measurement involved twenty-one questions categorized into seven groups with sixteen aspects, while the qualitative measurement comprised fifteen questions across four groups with eight aspects. By comparing and analyzing the construction input costs, labor costs, and duration with or without the participation of professional BIM consulting companies, this study determined the final economic benefits.

The findings indicated that, during the construction phase of railway projects, construction companies experienced a cost benefit of 197.6% when engaging professional BIM consulting services. However, the extent of the ultimate cost benefit hinged on various factors, including project complexity, workload, construction review, and the expertise of BIM technical personnel. Furthermore, the involvement of BIM consulting firms resulted in a reduction in work time, leading to time savings. Analysis of on-site inspection reports revealed that BIM work primarily focused on additional detailed modeling, consuming nearly half of the total work time. Other prominent aspects included construction cost management, process management, and further detailed modeling. In terms of BIM software usage, Revit emerged as the predominant application on both construction sites, likely attributed to its significant role in additional detailed modeling. The precision in quantity calculation and intricate modeling facilitated by BIM contributed to enhanced work efficiency. Moreover, this study identified tunnels as the primary location where BIM effectively addressed issues, possibly due to the intricate nature of tunnel construction.