Conference PaperPDF Available

Visualization of blockchain-based smart contracts for delivery, acceptance, and payment process using BIM

Abstract and Figures

Building Information Modeling (BIM) provides an excellent opportunity to digitally document and visually display construction projects' information throughout their whole lifecycle. Another recent technology that is fostering the digital transformation of the construction sector is blockchain-based smart contracts. In combination with BIM models, such smart contracts can be used for the automation of delivery, acceptance, and payment (DAP) processes in the construction industry. The DAP process can be modelled by using smart contracts and securely stored via a blockchain. Since smart contracts are programming codes, for stakeholders it is difficult to understand what is exactly written in the smart contracts. Therefore, it is necessary to visualize the status of the deployed smart contracts and the executed transactions. In this paper, a framework is highlighted to record and visualize the status of the DAP processes by combining BIM with smart contracts using the Business Process Model and Notation (BPMN) to develop a smart contract system. With the help of suitable visualization concepts, the individual transactions of the blockchain can be displayed in a comprehensible way. The feasibility of the framework is presented through an illustrative implementation of the smart contract system. The proposed framework can help project participants better understand the current state of a smart contract.
Content may be subject to copyright.
Visualization of blockchain-based smart contracts for
delivery, acceptance, and payment process using BIM
X Ye1*, N Zeng2 and M König1
1 Chair of Computing in Engineering, Department of Civil and Environmental Engineering,
Ruhr-University Bochum, Germany
2 Department of Construction Management and Real Estate, School of Civil Engineering,
Southeast University, China
*Corresponding author e-mail: xuling.ye@rub.de
Abstract. Building Information Modeling (BIM) provides an excellent opportunity to digitally
document and visually display construction projects’ information throughout their whole
lifecycle. Another recent technology that is fostering the digital transformation of the
construction sector is blockchain-based smart contracts. In combination with BIM models,
such smart contracts can be used for the automation of delivery, acceptance, and payment
(DAP) processes in the construction industry. The DAP process can be modelled by using
smart contracts and securely stored via a blockchain. Since smart contracts are programming
codes, for stakeholders it is difficult to understand what is exactly written in the smart
contracts. Therefore, it is necessary to visualize the status of the deployed smart contracts and
the executed transactions. In this paper, a framework is highlighted to record and visualize the
status of the DAP processes by combining BIM with smart contracts using the Business
Process Model and Notation (BPMN) to develop a smart contract system. With the help of
suitable visualization concepts, the individual transactions of the blockchain can be displayed
in a comprehensible way. The feasibility of the framework is presented through an illustrative
implementation of the smart contract system. The proposed framework can help project
participants better understand the current state of a smart contract.
Keywords: BIM, smart contracts, blockchain, process automation, smart contract visualization
1. Introduction
The visualization of building structures based on Building Information Modeling (BIM) has become
increasingly important in the architecture, engineering, and construction (AEC) industry and is
considered one of the most important areas of information and communication technology (ICT).
Newer visualization paradigms or technologies such as virtual reality (VR), augmented reality (AR)
and mixed reality (MR), or the animation of simulations of construction work are becoming more
common as well [8, 11]. Compared to construction products and processes, the visualization and
automation of business processes in construction projects has not gained enough attention.
The construction delivery, acceptance, and payment (DAP) process plays an important role in the
construction project management, which involves key project stakeholders, e.g., the client, the main
contractor, subcontractors, and related suppliers. The modeled DAP processes can be automated and
made more secure by representing them as smart contracts [4, 12]. However, the visualization of the
underlying process sequence of smart contracts is rarely explored. It leads to a lack of understanding
and control over the automated DAP process, and hence disputes or conflicts may occur. The Business
Process Model and Notation (BPMN) is an established process modelling method for the formal
description and visualization of business processes. It is also widely applied for the modeling of
various processes in the construction industry [1] To enhance the process visualization, BIM can
provide a multi-dimensional built environment, and BPMN can provide specified DAP process
models. The combination of BIM, BPMN, smart contracts and blockchain can thus lead to a better
representation of the DAP process and support project management.
This paper aims to provide an approach for visualizing the real-time DAP process using BIM,
smart contracts and blockchain. For visualization, the BIM model is connected to the smart contracts
based on the blockchain to visualize the individual states of the DAP process for each building
element in real-time. Our approach is presented through a smart contract system design and an
implementation with a real-world example.
2. Literature Review
Product visualization and process visualization are two distinct aspects of construction visualization
[8, 10, 11]. For product visualization, three-dimensional (3D) parametric modeling of building
products has been developed incrementally over four decades [11]. BIM has been widely applied as a
result of this evolutionary process. Construction process visualization is generally divided into two
categories, i.e., activity level visualization and operation level visualization [8, 10]. Graphical 3D
models can serve as an effective communication method at both levels. Further 3D building models
are “animated” by linking them to construction schedules to provide the fourth dimension, so-called
4D BIM [11].
Visualization of construction processes, progress, deviations, etc. by means of 4D BIM is well
researched [3, 19]. Some systems incorporate cost as a “fifth dimension” (5D) of project information
and aim to generate the bill of quantities (BOQ) and manage payments [13]. However, there are no
explicit steps to formalize and track the complete process between the contracting and the payment of
the services in the construction industry. This process involves at least two parties, namely the payer
(the client) and the payee (the contractor), and comprises three main steps - delivery, acceptance, and
payment, therefore referred to as the DAP process. Compared to the construction process (i.e.,
operations), the DAP process is fundamentally different, and the visualization of the DAP process is
rarely explored.
For an efficient construction DAP process management, as-designed information (e.g., the BIM
model), as-built information (e.g., 3D point cloud models) and as-paid information (e.g., transaction
records) are crucial. The interactions and information exchanges between the client and the contractor
are essential for DAP process execution. Therefore, process modeling methods, which consider
information exchange among multiple participants, such as BPMN, are appropriate for DAP process
visualization. Cheng et al. [2] used BPMN to model and visualize the construction supply chain.
Häußler et al. [6] conducted code compliance checking of railway designs by integrating BIM and
BPMN. Linking BPMN process maps of contracting and paying with the BIM model can contribute to
a BIM-enabled payment visualization.
With the development of digital transformation in the construction industry, the adoption of smart
contracts is becoming more frequent. Smart contracts serve as programmable applications to write,
verify and enforce transaction conditions automatically. Smart contract was first proposed by Szabo
and it was defined as “a computerized transaction protocol that executes the terms of a contract” [14].
Later the definition of smart contract was updated as “a set of promises, specified in digital form,
including protocols within which the parties perform on these promises.” [15]. Currently, smart
contracts serve as general-purpose programmable applications on blockchain platforms to write, verify
and enforce transaction conditions. In the construction field, a series of smart contract-enabled
applications were developed for DAP process automation [4, 12]. However, smart contract
visualization is rarely explored, let alone the visualization of the smart contract-enabled DAP process.
Jeong and Ahn [7] designed a framework for creating Ricardian contracts and visualized the mobile
User Interface (UI) and the User Experience (UX) of smart contracts. In their study, the contents of the
existing smart contracts were embedded in the block through byte code and then became a style sheet
document through the binding process or the verification process by the app. It was then automatically
converted to HTML or PDF through templates and data bindings for the visualization of the smart
contract. However, their research did not address the DAP process in construction. How to visualize
smart contracts in the context of construction DAP is an open issue that deserves further investigation.
3. Research Methodology
In this paper, a concept for the visualization of smart contracts with application in the DAP process is
proposed. The methodology is divided into two parts. The first part introduces the overall framework
of visualization of smart contracts for the construction DAP process. The second part clarifies the
execution workflows of the designed smart contract system from loading the BIM model to displaying
the DAP process and the corresponding blockchain transactions.
3.1. Smart contract visualization
The framework for smart contract visualization is shown in Figure 1. Three components are
distinguished, namely BIM data generation (Figure 1a), smart contract generation (Figure 1b), and
smart contract visualization (Figure 1c). This paper focuses on the concept of visualization.
BIM data generation: The BIM model, the corresponding bill of quantities, and related
construction schedule can provide essential information for a construction section or project. These
three files are used to create a billing plan that links construction work items to scheduled completion
dates, quantities, and payment information. All work that can be billed together at one time forms a
billing unit (BU) in the billing plan. All information respectively files for a contract will be provided
as an information container for the linked document delivery (ICDD) and are the basis for the
visualization of the smart contract. The generation of the billing plan and the ICDD has been done by
developing a billing model setup tool, which is explained in previous work [18].
Smart contract generation: Appropriate generation concepts have been developed for generating
the processing logic of a smart contract. Initially, clients and contractors design the smart contract
Figure 1. The framework of a) BIM data generation (left-upper), b) smart contract generation
(left-bottom), and c) smart contract visualization (right)and c) smart contract visualization
(right)
logic using BPMN. The behavior of each activity in BPMN is defined as “Action” in the smart
contract generation procedure. Each BPMN activity should declare only one “Action”. There are
different types of actions, e.g. "view", "modify" and "pay". With the help of "view", it is possible to
indicate that a BPMN activity only displays certain information, such as the start date of the event.
The "pay" type is used to trigger an automated payment action with a specified payment amount from
one user address to another user address. The smart contract logic based on BPMN can be
automatically translated into a smart contract via a smart contract generator [17]. The generated smart
contracts are written in high-level programming languages, such as Solidity from Ethereum. In
conclusion, the smart contract generation procedure provides the smart contract logic file in BPMN
format as an input of the smart contract system as well as the generated smart contracts for later
execution and visualization.
Smart contract visualization: The ICDD extracted files (i.e., the BIM model and the billing plan)
are used to provide the geometry, quantities, and payment information of the smart contract system.
The smart contract logic (BPMN) and the generated smart contracts are for establishing and
visualizing DAP processes. Each generated smart contract is compiled into bytecode and an
Application Binary Interface (ABI). A bytecode of a smart contract is a long string that only contains
numbers and letters in a specific order. The bytecode will be deployed in the blockchain so that the
blockchain can execute the smart contract code. An ABI of a smart contract is an interface represented
in JavaScript Object Notation (JSON) format that enables the interaction between the smart contract
system and the smart contracts deployed in the blockchain network. The ABI is deployed in the smart
contract system to show the callable functions of the deployed smart contracts and connects the smart
contract system with the blockchain network. The interaction (i.e. messaging and signing) between the
blockchain network and the smart contract system is realized with the help of the bytecode and the
ABI. The configuration files (i.e. the payment configuration and the progress entries) are essential
information for the implementation of the DAP processes. A common data environment (CDE) is used
as off-chain storage, namely a database outside of the blockchain. The ICDD, configuration files, the
smart contract logic (BPMN) file, and the smart contracts will be stored in this CDE and their
corresponding hash values will be stored in the blockchain.
In the smart contract system, the BIM model and the billing plan are linked together based on the
GUIDs of the BIM elements stored in both files to provide the building geometry, quantities, and
payment information at the same time. Each BU of the billing plan could have a DAP process that is
different from other BUs’ based on the actual situation of the construction project. By connecting each
BU with its specified DAP process, real-time DAP process information of each building element could
be displayed. Each activity of the DAP process diagram is a DAP process status, and the procedure
from one activity to another activity is defined as a DAP process status change. Each DAP process is
deployed as smart contract codes in the blockchain and its BPMN diagram is linked with the ABI to
provide the real-time DAP process status stored in the blockchain. Each status change of a DAP
process will generate a blockchain transaction and these blockchain transactions will be displayed in
the smart contract system. The design of the smart contract system for smart contract visualization will
be further explained in the following section.
3.2. Smart contract system execution workflow
To design a smart contract system for visualization, the functions of this system should be clarified.
The user-system interactions and operations of the smart contract system are shown in Figure 2, which
display the fundamental logic of the smart contract system. This logic can be divided into user
operations (Figure 2a) and system operations (Figure 2b), where the system operates according to the
user operations. This execution workflow aims to provide the main logic of the system execution and
the interaction logic of the four main components (i.e., the BIM model, the billing plan, the DAP
processes, and the blockchain transactions) of the smart contract system.
When the user selects one or multiple BUs, the linked BIM elements will be highlighted. Similarly,
when the user selects one or multiple BIM elements, all the linked BUs will also be highlighted. For
these selected BUs, a suitable DAP process can be assigned by the user based on the project need.
After the assignment, the system will activate the corresponding smart contract codes and record the
connection of the selected BUs and the DAP process in the blockchain. This record will be stored as a
blockchain transaction and displayed in the smart contract system. The DAP process of each BU can
be changed based on the actual construction progress. When the DAP process of some BUs has been
changed on the construction site, the stakeholder can select these BUs in the system and modify their
current DAP process status. In this way, the system will modify the status via the deployed smart
contracts. If successful, the new DAP process status will be highlighted in the BPMN diagram of the
system. Meanwhile, these status changes will be stored in the blockchain and displayed as blockchain
transactions in the smart contract system.
4. Illustrative implementation
4.1. Implementation workflow
A workflow for implementing the smart contract system is shown in Figure 3, which provides an
implementation solution for illustrating a construction DAP process example based on the proposed
smart contract system. The illustrative implementation steps are realized based on Hardhat, React,
xBIM, BPMN.io, and Etherscan, which can be grouped into four steps, namely system creation, front-
end realization, back-end realization, and smart contract deployment.
In the system creation step, a Hardhat project is first created to use the Ethereum network, where
Hardhat is a development environment to compile, test, and debug Ethereum software [5]. A React
front-end is then created within the Hardhat project to form a smart contract system, where React is a
JavaScript library for building user interfaces [9]. After the system creation step, the functions in the
React front-end can be realized. In this front-end realization step, a BIM viewer, a billing plan table, a
BPMN viewer, and the linking rule between the BIM model and the billing plan are implemented. The
BIM viewer is implemented via xBIM, where the xBIM provides an open-source software
development tool that allows users to read, create and view BIM in the Industry Foundation Classes
(IFC) format. The BPMN viewer is implemented via BPMN.io, where BPMN.io provides a web-based
BPMN viewer and editor to read and display BPMN 2.0 diagrams.
Figure 2. The execution workflow of the smart contract system explained via
user-system interactions and operations with a) user operations (upper) and b)
system operations (bottom)
The whole smart contract system can then be further realized by coding the functions connecting
the front-end to the blockchain as a back-end realization step. In this step, the linking rule between the
smart contract ABI file and the loaded BPMN is first coded. The user interaction with the highlighted
BIM element function as introduced in Section 3.2 is then realized to modify the DAP process real-
time status data stored in the blockchain for each billing unit of the billing plan. The corresponding
blockchain transactions can be displayed in the front-end by connecting with Etherscan, where
Etherscan is a block explorer of the Ethereum blockchain providing equitable access to blockchain
data.
After implementing all the functions for the system, the final step is to deploy the smart contracts.
In this step, the generated smart contracts from a corresponding BPMN file via the smart contract
generator are put into the “contracts” folder of the smart contract system. By executing this smart
contract system, the corresponding ABI file of the generated smart contracts will be created. If the
system is successfully executed, the implementation workflow is finished. This smart contract
deployment step is further explained in the following section.
4.2. Smart contract deployment
The DAP process of a billing unit (BU) is used to introduce the illustrative implementation, where a
BU stores the quantities and payment information for a group of construction works. This process was
defined in the previous work [16] and shown in Figure 4.
In this example, two roles (that of contractor and client) and eight tasks of the DAP process are
defined. The contractor first indicates the start of a specific BU. After finishing, (s)he indicates the
completion of this BU. The completion message will be sent to the client, who can then inspect the BU
for defects at the construction site. If no defect is detected, the BU can be automatically paid and the
entire BU process ends. If there are some defects, the BU will be divided into a completed-without-
defect part (BU.C) and a defective part (BU.D), of which the BU.C part is automatically paid and the
BU.D part is requested to be repaired. After the BU.D is repaired by the contractor, the client needs to
check the repaired BU.D and determine if the part is still defective. If so, the BU.D will be requested
again for repairs. Otherwise, the BU.D part will be paid automatically, and the entire DAP process for
that BU will end.
Figure 3. An implementation logic workflow for the smart contract system
The BPMN file within the process explained above (Figure 4) is loaded into a smart contract
generator for generating the corresponding smart contracts. As explained in the previous section, these
generated smart contracts are put into the “contracts” folder of the smart contract system. After
executing this smart contract system, the executed project is shown in Figure 5, where its folder
structure is displayed on the left, and some parts of a generated smart contract (i.e., SCExample.sol)
are presented on the right. For further details of the generated smart contracts, refer to Ye and König
2021b.
As shown in the folder structure, this smart contract system is named “Hardhat_React_DApp”
(Figure 5a), which contains a “contracts” folder (Figure 5b) and a “frontend” folder (Figure 5c). The
Figure 4. A BPMN example for a BU's DAP process
Figure 5. The folder structure (left) and a part of the generated smart
contract (right, SCExample.sol) of the smart contract system after smart
contract deployment
generated smart contracts (i.e., SCExample.sol and SCProcessFlow.sol files) were put into the
“contracts” folder (Figure 5b), and its corresponding ABI (i.e. SCExample.json file) was generated in
the “contracts” (Figure 5e) of the “frontend” folder after executing the smart contract system. The
“app” folder (Figure 5d) contains the functions explained in the “Front-end realization” and “Back-end
realization” steps of the previous section.
4.3. The user interface of the smart contract system
After implementation, the resulting User Interface (UI) of the designed smart contract system is shown
in Figure 6. This UI can be divided into four frames: a) BIM model, b) Billing plan, c) DAP process
(BPMN), and d) Blockchain transactions. The BIM model (Figure 6a) is used to provide GUIDs and
the 3D visualization of the construction project. The billing plan (Figure 6b) is used to provide
corresponding quantities and payment information based on this BIM model. After loading the BIM
model in the IFC format and the corresponding billing plan in the XML format, their linkage will be
automatically checked in the system. If the checking succeeds, the linkage between the BIM model
and the billing plan will be established. In this way, a billing unit will be highlighted when its
corresponding BIM element is selected, and vice versa.
The DAP process shown as a BPMN diagram (Figure 6c) is used to display the real-time status of
the DAP process for each BIM element. The real-time status and its historical status changes are
stored in the blockchain using the GUID and the used DAP process identifier of the BIM element as
the key. By selecting either a BIM element (highlighted in yellow of Figure 6a) or a billing unit item
(highlighted in gray of Figure 6b), its corresponding DAP process will be displayed and its current
status will be highlighted in green (see Figure 6c). By interacting with a highlighted billing unit, the
corresponding menu item will be displayed and its current DAP process status can be changed. The
change has to follow the process flow of the DAP. For example, after a BU is started, the BU could
only be set as completed by the contractor. Each modification of the DAP process status generates a
blockchain transaction, which is displayed in Figure 6d.
Figure 6. The user interface of the illustrative implementation of smart contract system
5. Conclusions and further research
The interactions and information exchange between project participants are essential for DAP process
execution, and they can be arranged in smart contracts. Although smart contracts can improve the
automation of business processes in construction projects, the actual execution is not visible for the
construction participants. To better understand and monitor the process status and support interactions,
visualization of smart contracts is essential. This paper proposes a framework consisting of BIM data
generation, smart contract generation, and smart contract visualization. The main focus of this paper is
the smart contract visualization realized through the smart contract system design. The execution
workflows of the smart contract system are introduced by explaining the logic of user-system
interactions and system operations. An illustrative implementation is provided for the designed smart
contract as a possible solution for the proposed framework, in which the implementation workflow
and the user interface are described in detail.
This research aims to provide an implementation solution of combining BIM with smart contracts
for visualizing the real-time DAP process. Further implementation of the smart contract system should
still proceed. For example, the connection between the smart contract system with a CDE has not yet
been considered in the paper. In the future, a real use case will be applied to verify the designed smart
contracts. User feedback should be collected for feasibility and further improvement of the smart
contract system. In addition to the DAP processes, the visualization and automation of other
construction management processes such as supply chain process can be considered in the future.
Acknowledgment
The study was conducted as part of the BIMcontracts research project funded by the German Federal
Ministry for Economic Affairs and Energy (BMWi) within the "Smart Data Economy" technology
program (project number: 01MD19006B).
References
[1] Borrmann, A., König, M., Koch, C., and Beetz, J. 2018. Building information modeling.
Technology foundations and industry practice. Springer, Cham, Switzerland.
[2] Cheng, J. C., Law, K. H., Bjornsson, H., Jones, A., and Sriram, R. D. 2010. Modeling and
monitoring of construction supply chains. Advanced Engineering Informatics 24, 4, 435
455.
[3] Deng, Y., Gan, V. J. L., Das, M., Cheng, J. C. P., and Anumba, C. 2019. Integrating 4D BIM
and GIS for Construction Supply Chain Management. J. Constr. Eng. Manage. 145, 4,
4019016.
[4] Hamledari, H. and Fischer, M. 2021. Construction payment automation using blockchain-
enabled smart contracts and robotic reality capture technologies. Automation in Construction
132, 103926.
[5] Hardhat. 2022. Ethereum development environment for professionals by Nomic Labs.
https://hardhat.org/. Accessed 9 January 2022.
[6] ußler, M., Esser, S., and Borrmann, A. 2021. Code compliance checking of railway designs
by integrating BIM, BPMN and DMN. Automation in Construction 121, 103427.
[7] Jeong, S. and Ahn, B. 2021. A study of application platform for smart contract visualization
based blockchain. J Supercomput, 118.
[8] Kamat, V. R., Martinez, J. C., Fischer, M., Golparvar-Fard, M., Peña-Mora, F., and Savarese, S.
2011. Research in Visualization Techniques for Field Construction. J. Constr. Eng. Manage.
137, 10, 853862.
[9] React. 2022. React - A JavaScript library for building user interfaces. https://reactjs.org/.
Accessed 9 January 2022.
[10] Rohani, M., Fan, M., and Yu, C. 2014. Advanced visualization and simulation techniques for
modern construction management. Indoor and Built Environment 23, 5, 665674.
[11] Sacks, R., Treckmann, M., and Rozenfeld, O. 2009. Visualization of Work Flow to Support
Lean Construction. J. Constr. Eng. Manage. 135, 12, 13071315.
[12] Sigalov, K., Ye, X., König, M., Hagedorn, P., Blum, F., Severin, B., Hettmer, M., Hückinghaus,
P., Wölkerling, J., and Groß, D. 2021. Automated Payment and Contract Management in the
Construction Industry by Integrating Building Information Modeling and Blockchain-Based
Smart Contracts. Applied Sciences 11, 16, 7653.
[13] Smith, P. 2016. Project Cost Management with 5D BIM. Procedia - Social and Behavioral
Sciences 226, 193200.
[14] Szabo, N. 1994. Smart contracts. Virtual School, 26.
[15] Szabo, N. 1996. Smart contracts: building blocks for digital markets. EXTROPY: The Journal
of Transhumanist Thought,(16) 18, 2.
[16] Ye, X. and König, M. 2021. Framework for Automated Billing in the Construction Industry
Using BIM and Smart Contracts. In Proceedings of the 18th International Conference on
Computing in Civil and Building Engineering, 824838.
[17] Ye, X. and König, M. 2021. From the graphical representation to the smart contract language: a
use case in the construction industry. In Proceedings of the 38th International Symposium on
Automation and Robotics in Construction (ISARC), 272279.
[18] Ye, X., Sigalov, K., and König, M. 2020. Integrating BIM- and Cost-included Information
Container with Blockchain for Construction Automated Payment using Billing Model and
Smart Contracts. In Proceedings of the 37th International Symposium on Automation and
Robotics in Construction (ISARC), 13881395.
[19] Zeng, N., Ye, X., Peng, X., and König, M. 2019. Applying Kanban System in Construction
Logistics for Real-time Material Demand Report and Pulled Replenishment. In Proceedings
of the 36th International Symposium on Automation and Robotics in Construction (ISARC),
10181025.
ResearchGate has not been able to resolve any citations for this publication.
Conference Paper
Full-text available
With the growing popularity of blockchain technology in the construction industry, smart contracts are becoming increasingly common. A smart contract is a self-executing contract, which contains if-then rules that automatically execute certain processes when certain conditions are met. Such smart contracts serve as programmable blockchain applications. Using blockchain-enabled smart contracts, many processes like construction contracting and payments can be automated. Since research on blockchain-enabled smart contracts in the construction industry is still theoretical, researchers usually assume that users (e.g. clients, contractors) can directly program the conditions in a smart contract. However, it is difficult for stakeholders to program smart contracts themselves due to a lack of knowledge. The smart contracts developed by programmers might not fully represent stakeholders' ideas. Therefore, this paper proposes an approach that illustrates how graphical workflow notations (e.g. BPMN, YAWL) can be translated into smart contract programming languages (e.g. Solidity, Vyper). In this way, non-programmers can also design and generate their own smart contracts. To test the feasibility of this approach, an illustrative example is presented for generating smart contracts displaying automated the reporting, checking and payment process of construction works. In particular, the smart contracts in this example are translated from YAWL graphical representations into Solidity smart contract languages. Finally, improvements and further developments of the approach are discussed in several aspects.
Article
Full-text available
Construction projects usually involve signing various contracts with specific billing procedures. In practice, dealing with complex contract structures causes significant problems, especially with regard to timely payment and guaranteed cash flow. Furthermore, a lack of transparency leads to a loss of trust. As a result, late or non-payment is a common problem in the construction industry. This paper presents the concept of implementing smart contracts for automated, transparent, and traceable payment processing for construction projects. Automated billing is achieved by combining Building Information Modeling (BIM) approaches with blockchain-based smart contracts. Thereby, parts of traditional construction contracts are transferred to a smart contract. The smart contract is set up using digital BIM-based tender documents and contains all of the relevant data for financial transactions. Once the contracted construction work has been accepted by the client, payments can be made automatically via authorized financial institutions. This paper describes the framework, referred to as BIMcontracts, the container-based data exchange, and the digital contract management workflow. It discusses the industry-specific requirements for blockchain and data storage and explains which technical and software architectural decisions were made. A case study is used to demonstrate the current implementation of the concept.
Article
Full-text available
In recent years, blockchain, which is the base technology of the 4th industrial revolution, is rapidly emerging as an alternative to the centralized data management method. An application platform for providing blockchain networks and services to both the general public and the underprivileged (elderly people, farmers, people with disabilities) is essential. In particular, the socially vulnerable (defective families, grandparents, children, multicultural families, settlers, individuals living in basic conditions) need clear guidelines for complex and high-level contracts. Therefore, in this study, we designed a smart contract visualization application platform to improve user convenience. This system provides an easy-to-use interface for the socially vulnerable and underprivileged and presented guidelines for signing complex and high-level contracts. In addition, we designed a mobile UI/UX for smart contracts and enabled the automatic creation of Ricardian contracts.
Conference Paper
Full-text available
Payment issues are necessary in the construction industry, often manifested by high levels of arrears and long-term payment delays. An automated payment could be a solution to speed-up the payment process after successful completions. In this paper, a framework is proposed for the automated payment via Building Information Modeling (BIM), Linked Data, Smart Contract and Blockchain technologies. Geometrical and payment-related data are stored as BIM-based linked data. Linked Data technology connects a BIM model with its related Bill of Quantities (BoQ) and Quantity Take-Off (QTO). Based on the transparency, traceability and collaboration of the Blockchain technology, an automated payment can be secured. To integrate such an information container with Blockchain for the automated payment, an additional information model called Billing Model (BM) is proposed. Thereby, each Billing Unit (BU) stores one or more construction work tasks with a related payment and a related due date. Together with the corresponding Smart Contract rules, the BM can automate payment via a Blockchain. Several aspects of improvement and further development are discussed in the end.
Article
Full-text available
Construction supply chain management (CSCM) requires the tracking of material logistics and construction activities, an integrated platform, and certain coordination mechanisms among CSCM participants. Researchers have suggested the use of building information modeling (BIM) technology to monitor construction activities and manage construction supply chains. However, because material warehousing and deliveries are mostly performed outside construction project sites, project information from a single BIM model is insufficient in meeting the needs of construction supply chain management. In this research, an integrated framework was developed based on four-dimensional (4D) BIM and a geographical information system (GIS) for coordination of construction supply chains between the construction project sites and other project related locations, such as supplier sites and material consolidation centers. The proposed integration was used to solve three common tasks in CSCM, namely (1) supplier selection, (2) determination of number of material deliveries, and (3) allocation of consolidation centers, using information from 4D BIM and GIS. The proposed 4D BIM-GIS framework was demonstrated via case studies. The results of the case studies indicated that determinations of supplier and number of deliveries need to take into account both the transportation distance and material unit price. Mathematical solutions were also generated to support decision making for the allocation of consolidation centers in congested regions with long transportation distances. The outcomes of this paper serve as a decision support base for a more efficient CSCM in the future.
Article
Full-text available
This paper explores the practical issues and constraints faced by project cost management professionals in the implementation and effective utilization of the various software, technologies and tools that are now available in the rapidly developing Building Information Modeling (BIM) sphere. BIM and its allied digital technologies and tools provide enormous opportunities for project cost management professionals to dramatically improve the quality, speed, accuracy, value and sophistication of their cost management services and therein ensure their future as key players in the BIM world. However, the profession has generally been slow to embrace and evolve with the full potential that these technologies can provide. There is now considerable momentum building as firms realize they have to embrace these technologies and see competitors seizing market advantage through developing expertise in the field. The purpose of this paper is to explore the issues faced by firms and to identify successful practices, procedures and strategies that firms are implementing. The research methodology for the paper is based on detailed interviews with Quantity Surveying firms in Australia. The results show that the interviewed firms are spending a lot of time and effort in developing their expertise and that there was a consistent pattern in relation to the main issues and problems and what was needed to be successful. The greatest issues related to the quality/comprehensiveness of the BIM models, difficulties with designers not providing full access to the models and software/standards compatibility issues. Successful strategies were clearly based on strong commitment and leadership from company directors and positive approaches to dealing with the issues and challenges faced. The paper concludes with a range of recommendations and strategies to help address these issues.
Article
This paper introduces an autonomous payment administration solution, integrating blockchain-enabled smart contracts and robotic reality capture technologies. The construction progress is captured, analyzed, and documented respectively using sensing, machine intelligence, and as-built building information models (BIM). The progress data is stored in a distributed manner using content addressable file sharing; it is then broadcasted to a smart contract which administers payments and transfers lien rights respectively using crypto currencies/tokens and non-fungible tokens (NFT). The method was successfully implemented for payments to 7 subcontractors in two real-world commercial construction projects in Canada and United States where progress was captured using a camera-equipped unmanned aerial vehicle (UAV) and an unmanned ground vehicle (UGV) equipped with a laser scanner. The method eliminates reliance on today's heavily intermediated payment applications and showed promise for achieving accurate, efficient, and timely payment administration. Future work should further explore the connections between off-and on-chain realities.
Article
Code compliance checking has been the subject of scientific research for more than four decades and has been put into practice in numerous projects. To date, however, no universally valid, sustainable approach to the rule-based compliance checking of models has been established. Visual programming languages are easier to understand and thus more transparent than textual formats. The study presented here analyzes the requirements specified in the guidelines of the Deutsche Bahn AG regarding the technical design of structures in railway construction and examines the feasibility of implementing these rules using BPMN and DMN. The rules analyzed are categorized into 12 different classes. Depending on the guideline subset, the BPMN/DMN approach was found to be useable in 37%-75% of the 943 rules examined. Considering only those rules that are relevant for the digital railway model, 68% of the rules can be represented and automated using BPMN and DMN.
Book
Building Information Modeling (BIM) refers to the consistent and continuous use of digital information throughout the entire lifecycle of a built facility, including its design, construction and operation. In order to exploit BIM methods to their full potential, a fundamental grasp of their key principles and applications is essential. Accordingly, this book combines discussions of theoretical foundations with reports from the industry on currently applied best practices. The book’s content is divided into six parts: Part I discusses the technological basics of BIM and addresses computational methods for the geometric and semantic modeling of buildings, as well as methods for process modeling. Next, Part II covers the important aspect of the interoperability of BIM software products and describes in detail the standardized data format Industry Foundation Classes. It presents the different classification systems, discusses the data format CityGML for describing 3D city models and COBie for handing over data to clients, and also provides an overview of BIM programming tools and interfaces. Part III is dedicated to the philosophy, organization and technical implementation of BIM-based collaboration, and discusses the impact on legal issues including construction contracts. In turn, Part IV covers a wide range of BIM use cases in the different lifecycle phases of a built facility, including the use of BIM for design coordination, structural analysis, energy analysis, code compliance checking, quantity take-off, prefabrication, progress monitoring and operation. In Part V, a number of design and construction companies report on the current state of BIM adoption in connection with actual BIM projects, and discuss the approach pursued for the shift toward BIM, including the hurdles taken. Lastly, Part VI summarizes the book’s content and provides an outlook on future developments. The book was written both for professionals using or programming such tools, and for students in Architecture and Construction Engineering programs.