JP7616620B2 - Construction information management system - Google Patents

Description

Article 30, paragraph 2 of the Patent Act applies (1) Published on October 30, 2019: Report on the results of the "i-Construction Systems Science" endowed lecture course (2) Published on November 20, 2019: Website: http://www.i-con.t.u-tokyo.ac.jp/ (3) Published on December 10, 2019: Website: http://www.archifuture-web.jp/magazine/465.html (4) Published on February 17, 2020: Demonstration test of a witness inspection system using blockchain, Ministry of Land, Infrastructure, Transport and Tourism Kanto Regional Development Bureau Kita-Shuto National Highway Office

The present invention relates to a construction information management system .

Conventionally, in construction work, construction work is requested to a corresponding business operator (contractor) according to the construction stage.
That is, construction work is carried out by many businesses that specialize in each type of construction work. For this reason, when a client places an order for construction work with a prime contractor (the highest-level contractor), the prime contractor places orders for each type of construction work in the construction work with lower-level subcontractors, i.e., first-level subcontractors, who then place orders with second-level subcontractors, who then place orders with third-level subcontractors, resulting in a complex, multi-layered contract structure (see Figure 1 below).

In addition, in order for the requesting party who has ordered the work to check the work being performed by the contractor who has undertaken the work, construction status data showing this construction status is acquired at each pre-set, specified construction stage at which the construction status can be confirmed, and is accumulated in a specified storage device.
That is, an inspection of the construction status is carried out, and the contractor leaves historical information such as photographs taken of the construction site being inspected and measurement data as construction status data indicating the construction status for the client (see, for example, Patent Document 1).

JP 2010-101158 A

However, if the construction status data stored in the storage is tampered with, when a problem occurs with the quality of the work, it will be impossible to determine which construction step is the cause, and traceability for managing the quality, finished form, and progress of each construction step, as well as for maintaining the structure after it has been constructed, will be reduced.
Furthermore, the client side inspects the on-site completed form and quality using the construction management information, but if the construction status data is tampered with, the reliability of the inspection results will decrease.
As mentioned above, due to the low traceability of construction status data, many inspections, including on-site inspections, are required during construction to check the completed form and quality of the work, which places a burden on both the contracting party and the recipient party.

The present invention has been made in consideration of the above circumstances, and aims to provide a construction information management system that makes it easy to manage and inspect the quality, finished form, and progress of each construction project in a construction work, and also improves traceability for maintaining and managing structures after construction.

In order to solve the above problems, the construction information management system of the present invention is a construction information management system that manages construction status data indicating the status of construction based on electronic contracts between clients and contractors in each layer of contracting relationship for construction work in a construction project, and is characterized in that it is implemented in a blockchain and has a smart contract that creates the electronic contract in the blockchain, and a data storage application program interface (API) that writes and stores the construction status data indicating the status of the construction in storage in correspondence with a contract ID that identifies the electronic contract, and writes a first hash value of the construction status data in correspondence with the contract ID to the blockchain.

The construction information management system of the present invention further includes an inspection system that corresponds to the inspection rules described in the electronic contract, inspects the construction status data, and writes the data to the blockchain as execution condition data in correspondence with the contract ID.

The construction information management system of the present invention is characterized in that, when the inspection system uses the construction status data to inspect construction, it obtains a second hash value of the construction status data read from the storage, compares the second hash value with the first hash value, and determines whether the construction status data has been tampered with.

The construction information management system of the present invention is characterized in that the smart contract pays the price of the construction according to the construction status data according to the payment rules in the execution conditions of the electronic contract.

The construction information management system of the present invention is characterized in that the smart contract forms a tree structure of contracts indicated by the electronic contracts in the multi-layered contract relationship by associating the contract IDs between the electronic contracts of each layer in the multi-layered contract relationship.

The construction information management method of the present invention is a construction information management method that manages construction status data showing the status of construction based on electronic contracts between clients and contractors in each layer of contracting relationship for construction work in a construction project, and is characterized in that a smart contract is implemented in a blockchain, and includes an electronic contract creation process for creating the electronic contract in the blockchain, and a construction status data writing process in which a data storage application program interface (API) writes and stores the construction status data showing the status of the construction in storage in correspondence with a contract ID that identifies the electronic contract, and writes a first hash value of the construction status data in correspondence with the contract ID to the blockchain.

The program of the present invention is a program that causes a computer to function as a construction information management means that manages construction status data in a construction information management system that uses a blockchain to write hash values of the construction status data stored in storage, based on electronic contracts between clients and contractors in each layer of contracting relationship for construction work, and causes the computer to function as the construction information management means that is implemented in the blockchain, creates the electronic contract in the blockchain, writes the created electronic contract in the blockchain, and manages the construction status data using the hash values.

The present invention provides a construction information management system, construction information management method, and program that improves the traceability of managing the quality, finished form, and progress of each construction step in a construction project, as well as the maintenance and management of structures after construction.

This is a diagram of the construction contract relationship showing an example of the contract form for each construction work in the construction project. FIG. 2 is a conceptual diagram for explaining the management of construction information of construction work, inspection of construction information data, and payment of the construction fee corresponding to the inspection in the present invention. 1 is a block diagram showing an example of the configuration of a construction information management system according to an embodiment of the present invention; 1 is a block diagram showing a practical example of a construction information management system according to an embodiment of the present invention;

FIG. 1 is a diagram of a construction contract relationship showing an example of the form of each contract for construction work.
As shown in Fig. 1, in the construction of a construction project, for example, there is a client who orders the construction project, a contractor (prime contractor) who receives an order for the construction project from the client, and a business operator who specializes in each type of construction project that is subcontracted from the contractor. That is, in this embodiment, the client in the construction contract refers to the business operator who orders the construction project. Also, among the clients, a business operator who does not actually carry out the construction work is referred to as the client. The contractor is the business operator who receives an order for the construction project.
In addition, each construction type is further subdivided into several sub-construction types, with first-tier subcontractors being those who are directly requested to carry out construction work by the contractor, and second-tier subcontractors being those who are requested to carry out construction work by the first-tier subcontractors, forming a tree structure that corresponds to the multi-layered contracting relationships of construction work within a building project.

Then, the construction work of the corresponding construction type is contracted out from the client to the prime contractor, from the prime contractor to the first-tier subcontractor, and from the first-tier subcontractor to the second-tier subcontractor, and a contract corresponding to the construction work is issued for each of them.
An inspection of the construction work will be carried out in accordance with this contract, and based on the results of the inspection and the execution conditions described in the contract, the client who placed the order for the construction will pay the contractor who received the order for the construction work.

FIG. 2 is a conceptual diagram for explaining the management of construction information of construction work, inspection of construction information data, and payment of the construction fee corresponding to the inspection in the present invention.
The construction information management system of the present invention uses blockchain technology, which has been widely used in various fields in recent years, to convert contracts for construction work at a construction site into electronic contracts in the form of electronic data, and manages the quality of the construction (e.g., quality relative to control values) and completed form in response to the inspection rules in the execution conditions for the construction work, based on information on which construction work each of the client and customer on the ordering side and the contractor on the receiving (contracting) side is undertaking, and is configured to pay for the construction work according to the amount completed in accordance with the payment rules in the execution conditions.

Each of the client and the customer inputs contract data into a user terminal indicating the contents of the construction contract, including the ordering party (client or customer), the receiving party (contractor), control values for construction inspection, contract amount, and payment execution conditions.
As a result, the user terminal (web browser) requests, via an application that requests the issuance of an electronic contract, a process to write an electronic contract including the ordering party (client or orderer), the contract amount (amount paid in consideration of the construction work), the receiving party (contractor), the control value for the inspection of the construction work, and the execution conditions of payment (execution condition data) to a blockchain smart contract 30 generated by a blockchain node (blockchain node 21 described later).

Then, the smart contract 30 implemented in the blockchain generates an electronic contract on the blockchain based on the data input by the ordering party. By writing the electronic contract corresponding to the construction contract on the blockchain, it is possible to prevent tampering with the electronic contract.
In addition, the design plan/construction management system (construction management system 220 described later) outputs information on the completed form (construction status data) of the construction contracted by the contractor, which is input by the contractor performing the construction (e.g., the contractor), to a data storage (not shown, data storage 50 described later).
The data storage stores information on the completed form (construction status data) for the construction contracted by the contractor, which is supplied from the design plan/construction management system, in its own storage (storage 52 described later), and writes the hash value of this construction status data to the blockchain.

As a result, each piece of actual construction status data indicating the completed state of construction is accumulated in chronological order in the data storage, and each hash value of this construction status data is correspondingly written into the blockchain, thereby preventing tampering with the construction status data in the data storage.
In other words, when the inspection system 60 performs an inspection, it calculates a hash value of the construction status data stored in the data storage and compares it with the hash value recorded on the blockchain to confirm whether the construction status data in the data storage used for the inspection has been tampered with. This ensures the reliability of each piece of construction status data stored in chronological order in the data storage, improves the traceability of the construction status data, and ensures the quality of the results of the inspection performed in response to each construction.

In addition, the inspection system 60 uses techniques such as analytical graphic processing to inspect whether the construction status data is of a quality that corresponds to the control value and to what extent the construction has been completed, and then performs a process of writing the inspection results to the blockchain as execution condition data.
The results of inspection of the construction completion are written to the blockchain as execution condition data, and the smart contract 30 compares the execution condition data with the execution conditions to determine whether or not to pay the consideration, and then processes the payment of the consideration, for example, transferring value as consideration from the wallet address of the ordering party to the wallet address of the receiving party.

The above-mentioned configuration allows for a construction information management system that is inexpensively built using blockchain technology to improve the traceability of construction status data for each construction project, reduce on-site inspections that are a burden on both the ordering and receiving parties by automating inspections, and make it possible to pay for construction work at any time based on execution condition data that shows the results of the inspections.

FIG. 3 is a block diagram showing an example of the configuration of the construction information management system 1 according to an embodiment of the present invention.
In FIG. 3 , the construction information management system 1 includes an application 10, a PtoP network 20, a smart contract 30, a database 40, data storage 50, and an inspection system 60.
In addition, the application 10 is implemented on a Web (World Wide Web) server, and includes, as application software, a front end 11 and an API (Application Programming Interface) 12 for executing a smart contract.
In addition, the PtoP (Peer to Peer) network 20 is equipped with software that generates and manages blockchains, and includes multiple blockchain nodes 21 that are connected by a PtoP network configuration.

The smart contract 30 is software (program code) placed on the blockchain, and generates an electronic contract in each block of the blockchain and pays the price for construction corresponding to the execution conditions with a predetermined value (e.g., virtual currency). The external payment system 210 performs payment processing of the price for construction between the client, the orderer, and the contractor with a predetermined currency corresponding to the value value supplied to the smart contract 30 from the blockchain node 21.
The database 40 is a storage unit in which the history of processing for the blockchain, such as metadata of construction status data, is written, and is a schemaless NoSQL (non-relational) database designed specifically for a specific data model.

The data storage 50 is a database that accumulates actual data of the construction status data, and includes a data storage API 51 and a storage 52 .
The data storage API 51 performs processes such as accessing the storage 52 from an external device (for example, the construction management system 220 described later), creating metadata for the construction status data, writing the created metadata to the database 40, creating a hash value for the construction status data (hash value H1 described later), and writing the created hash value to the blockchain.
The storage 52 is a storage unit in which data is accumulated in a predetermined table format, and actual construction status data supplied from an external device is written and stored by the data storage API 51 .

The inspection system 60 includes a quality and finished form confirmation program 61 and a result viewing viewer 62. Each of the quality and finished form confirmation program 61 and the result viewing viewer 62 is, for example, application software implemented on a Web server.
The quality and completed form confirmation program 61 performs an inspection to compare the data of the inspection items listed in the execution conditions in the construction status data stored in the storage 52 with the control values, and writes the inspection results as execution condition data into the blockchain via the blockchain node 21.
The result viewing viewer 62 is a viewer used to view execution condition data, which is the inspection result, actual measured values of the measured finished shape of the construction target (an example of construction status data), images of a three-dimensional shape model corresponding to the design data of the construction target, and the like.

Below, using Figure 3, an example of the operation of the construction information management system, including the generation process of an electronic contract, management of construction status data, inspection based on the construction status data, and payment of fees based on the execution condition data of the inspection results, will be explained using earthworks in a construction project as an example.
<Process #0: Implementing a smart contract on the blockchain>
Step S0: The smart contract 30 generates an electronic contract on the blockchain and serves as application software for paying for construction work in accordance with execution condition data including the inspection results of the construction status data. The program code is implemented (placed) on the blockchain as a software agent by the blockchain node 21.

<Process #1: Generation of site ID by orderer (user 501)>
Step S1_1: The client inputs the value (e.g., an amount in virtual currency) of the payment to be made to the prime contractor (main contractor) who is the recipient of the order for the construction work (civil work) on the display screen of the user terminal (implemented with a web browser) displayed by the front end 11.

Step S1_2: The front end 11 outputs the value of the entered construction fee to the smart contract execution API 12 (request).

Step S1_3: When the amount of compensation is supplied, the smart contract execution API 12 outputs the amount of compensation supplied to the blockchain (BLC) smart contract (BLC request).

Step S1_4: The smart contract 30 generates a creator address (e.g., the wallet address of the client) of the payment source (client) of the amount of the consideration, a site address (e.g., the wallet address of the client) of the payment destination (contractor, e.g., prime contractor) of the amount of the consideration, and a site ID (identifier). This site ID is identification information that identifies the entire civil engineering work to be ordered from the contractor (prime contractor).
Then, the smart contract 30 outputs the generated creator address, site address and site ID to the application 10 (BLC response).

The wallet addresses are set for each business operator with numbers that do not interfere with each other, and indicate the address of the payee for the work in the construction. Since the wallet addresses are unique numbers for each business operator and do not interfere with each other, they are used to identify each business operator who has contracted for construction.

Step S1_5: The smart contract execution API 12 outputs the creator address, site address, and site ID provided from the blockchain smart contract to the front end 11 (response).

Step S1_6: The front end 11 displays the input creator address, site address, and site ID on the display screen of the user terminal via a web browser and notifies user #1 (the orderer).

<Process #2: Creating a contract from the purchaser to the recipient>
In the following description, for example, the orderer is the prime contractor and the recipient is the first-tier subcontractor.
Step S2_1: The orderer inputs the contract ID (ID#1111), the site address of the orderer (i.e., the contractor who is the orderer of the construction work), the amount of the consideration to be paid to the first subcontractor, the construction type of the construction work to be ordered, the data items (construction information management items) to be inspected in the construction status data, and the execution conditions of the payment of the consideration from the display screen for creating a contract on the user terminal displayed by the front end 11. The contract ID is identification information for identifying the electronic contract generated by the smart contract 30.

Here, the execution conditions include the due date for paying the consideration for the construction work, the management values for the construction information management items that determine whether or not the consideration should be paid, and the like.
For example, in the case of construction involving compaction in earthwork construction, the control value is the number of times the roller is compacted, determined in advance through experiments using similar soil.

Step S2_2: The front end 11 outputs (requests) the contract ID (ID#1111), the site address, the amount of the consideration to be paid, the type of construction, the construction information management items, and the execution conditions to the smart contract execution API 12.

Step S2_3: When the smart contract execution API 12 is supplied with the data of the contract ID (ID#1111), site address, amount of payment, construction type, construction information management items, and execution conditions, it outputs the input contract ID (ID#1111), site address, amount of payment, construction type, construction information management items, and execution conditions to the smart contract 30 in the blockchain (BLC request).

Step S2_4: As a result, the smart contract 30 generates the site address of the contractor (first-level subcontractor) and generates an electronic contract that corresponds to the contract ID (ID#1111) and includes the site address of the orderer, the site address of the contractor, the amount of the payment, the type of construction, construction information management items, and execution conditions.
Then, the smart contract 30 outputs the contract ID (ID #1111), the site address of the orderer, the site address of the contractor, the amount of the payment, the type of construction, the construction information management items, and the execution conditions to the application 10 (BLC response).

Step S2_5: The smart contract execution API 12 outputs the contract ID (ID#1111) supplied from the blockchain smart contract 30, the orderer's site address, the contractor's site address, the amount of the payment, the type of construction, the construction information management items, and the execution conditions to the front end 11 (response).

Step S2_6: The front end 11 outputs the contract ID (ID#1111), the site address of the customer, the site address of the contractor, the amount of the payment, the type of construction, the construction information management items, and the execution conditions to the display screen, and notifies the customer (prime contractor).
In addition, an electronic contract (contract ID is ID#1110) for the construction contract is generated from the client to the prime contractor, who is the recipient of the order, and from the client to the first-tier subcontractor, who is the recipient of the order.

<Process #3: Linking of electronic contract by the contractor>
The following describes the association of electronic contracts for construction work between the prime contractor, who is the orderer, and the first-tier subcontractor, who is the recipient of the order.
Step S3_1: The contractor (first-level subcontractor, user #1) inputs the contract ID (ID #1110) and the related contract ID (ID #1111) into the contract association field on the display screen for contract association on the user terminal (displayed by the implemented web browser).

Step S3_2: The front end 11 outputs (requests) the data of the contract ID (ID#1110) and the contract ID (ID#1111) entered in the contract association field to the smart contract execution API 12.

Step S3_3: When the smart contract execution API 12 is supplied with the data of the contract ID (ID#1110) and the contract ID (ID#1111), it outputs the data of the supplied contract ID (ID#1110), the contract ID (ID#1111), and the address of the issuer of the contract ID (ID#1111) (i.e., the creator address of the prime contractor who is the orderer) to the smart contract 30 in the blockchain (BLC request).

Step S3_4: When the smart contract 30 is supplied with the data of the contract ID (ID#1110) and the contract ID (ID#1111), it outputs the supplied contract ID (ID#1110), the contract ID (ID#1111), the address of the issuer of the contract ID (ID#1111) (i.e., the creator address of the prime contractor who is the orderer), and the address to which the contract ID (ID#1111) is issued (i.e., the creator address of the primary subcontractor who is the orderer) to the application 10 (BLC response).

Step S3_5: The smart contract execution API 12 outputs the contract ID (ID#1110) and the contract ID (ID#1111) supplied from the blockchain smart contract 30, and the address to which the site ID was issued, to the front end 11 (response).

Step S3_6: The front end 11 outputs the data of the contract ID (ID#1110) and the contract ID (ID#1111) to the display screen of the user terminal of the orderer corresponding to the address of the issuer of the contract ID (ID#1110), and notifies user #1 (the prime contractor who is the orderer) to approve the association of the electronic contract for the contract ID (ID#1110) with the electronic contract for the contract ID (ID#1111) (i.e., approval of the construction order to the prime contractor's first-tier subcontractor).

<Process #4: Approval of the contract by the purchaser>
Step S4_1: The orderer (user #1, the prime contractor) checks the contract ID (ID #1110) and the contract ID (ID #1111) related to this contract ID (ID #1110) on the display screen of the web browser on the user terminal, and inputs data indicating approval (approval data) in the approval column of the electronic contract on the display screen.

Step S4_2: The front end 11 outputs (requests) the approval data for the electronic contracts for the contract ID (ID#1110) and the contract ID (ID#1111) entered in the approval association field of the electronic contract to the smart contract execution API 12.

Step S4_3: When approval data for the association of the electronic contracts of the contract ID (ID#1110) and the contract ID (ID#1111) is provided, the smart contract execution API 12 outputs the approval data for the association of the electronic contracts of the contract ID (ID#1110) and the contract ID (ID#1111) to the smart contract 30 in the blockchain (BLC request).

Step S4_4: As a result, when approval data for associating the electronic contracts of contract ID (ID#1110) and contract ID (ID#1111) is provided, the smart contract validates the electronic contract of contract ID (ID#1111) and outputs confirmation data to application 10 indicating that the electronic contracts of contract ID (ID#1110) and contract ID (ID#1111) have been associated (BLC response).

Step S4_5: The smart contract execution API 12 outputs confirmation data relating to the electronic contracts associated with the contract ID (ID#1110) and the contract ID (ID#1111) to the front end 11 (response).

Step S4_6: The front end 11 outputs confirmation data indicating that the electronic contracts of the contract ID (ID#1110) and the contract ID (ID#1111) have been associated to the display screen of the web browser of the user terminal of the user #1 (orderer), and notifies the user #1 (orderer) that the electronic contracts of the contract ID (ID#1110) and the contract ID (ID#1111) have been associated.

By the above-mentioned processes #2, #3, and #4, the electronic contract (ID#1111) between the prime contractor (orderer) and the first-tier subcontractor (received contractor) is associated with the electronic contract (ID#1110) between the purchaser (orderer) and the prime contractor (received contractor) by the smart contract 30 implemented in the blockchain, and the contract ID (ID#1110) is linked (associated) with the contract ID (ID#1111) as shown in the tree structure of the electronic contract in Figure 1.

In addition, when the first subcontractor becomes the orderer and the second subcontractor becomes the recipient, the second subcontractor performs the above process #2 and creates an electronic contract with a contract ID of, for example, ID #1112, using the smart contract 30.
Then, in process #3, the secondary subcontractor requests the primary subcontractor, who is the orderer in the electronic contract for the contract ID (ID#1111), to associate the contract ID (ID#1111) with the contract ID (ID#1112).

As a result, the primary subcontractor performs process #3 and processes approval (approval by smart contract 30) of the association between contract ID (ID #1111) and contract ID (ID #1112).
This allows the prime contractor to associate the contract ID (ID#1111) with the contract ID (ID#1112).
Then, by carrying out the above-mentioned process between the orderer and the contractor, a tree structure is generated, as shown in FIG. 2, indicating the contract relationship for the construction work indicated by the site ID (the corresponding relationship between the orderer and the contractor in each of the electronic contracts), with the contract ID (ID#1110)-contract ID (ID#1111)-contract ID (ID#1112).

<Process #5: Writing construction status data to database>
Step S5_1: The construction status data of the construction in each electronic contract is input from the construction management system 220 to the data storage 50 by the business operator of the orderer or the contractor (the contractor actually performing the construction).
Here, for example, if the type of construction is earthwork construction, the contractor (business operator) will perform the compaction of the embankment at the site as part of the construction work described in the electronic contract.
At the actual construction site, the contractor uses a bulldozer to spread the soil transported by a dump truck to create an embankment, and then compacts (rolls) the embankment with a roller.

The builder then obtains information on the material of the embankment, information for determining the number of times the roller is compacted, and measurement data indicating the finished shape of the embankment constructed by the measuring device.
That is, the construction status data includes, for example, time series data of position coordinates from the Global Navigation Satellite System (GNSS) that shows the movement path of heavy machinery such as rollers, material information of the soil used as the construction fill, three-dimensional point clouds showing the finished shape, and electronic data such as captured images of the construction target and construction drawings of the construction target.

Step S5_2: In the data storage 50, the data saving API 51 creates a hash value H1 of the construction status data supplied by the construction management system 220 by the construction operator using a predetermined hash function.
Then, the data storage API 51 transmits the hash value H1 of the created construction status data and the contract ID corresponding to the construction to the blockchain node 21.
The blockchain node 21 writes the hash value H1 supplied from the data storage API 51 into a specific block in association with the contract ID, and transmits this block ID to the data storage 50.

Step S5_3: The data storage API 51 writes and stores the construction status data (actual data) input from the construction management system 220 in the storage 52, corresponding to the contract ID and each of the block IDs from the blockchain node 21.
As a result, the hash value H1 of the construction status data stored in storage 52 is written to a block of the blockchain, and by comparing this hash value H1 with the hash value H2 of the construction status data, which is the actual data stored in the storage when an inspection is performed, it is possible to determine whether or not the data has been tampered with, thereby improving the reliability of the construction status data used in the inspection and enabling traceability of the quality of construction for each electronic contract using the contract ID.

In addition, by writing and storing the actual construction status data in the data storage 50 and writing a hash value of the construction status data to the blockchain, large amounts of construction status data are not accumulated in each block of the blockchain, and the amount of data in the blockchain can be reduced.
Therefore, according to this embodiment, the blockchain prevents tampering with the above-mentioned construction status data and reduces the amount of data, thereby improving quality traceability.

<Process #6: Inspection of construction information management items in construction status data>
Step S6_1: User #2 (e.g., the client), who is an inspector inspecting the construction status, inputs the contract ID of the electronic contract corresponding to the construction to be inspected to the inspection system 60 via a web browser on the user terminal.

Step S6_2: In the inspection system 60, the quality and finished form confirmation program 61 requests the data storage 50 to search for construction status data corresponding to the input contract ID.

Step S6_3: When a search request for construction status data is supplied from the user terminal, the data storage API 51 searches the storage 52 for construction status data corresponding to the contract ID.
Then, the data storage API 51 reads the searched construction status data from the storage 52 and outputs the read construction status data to the inspection system 60 .

Step S6_4: The quality and finished form confirmation program 61 uses the same hash function as the hash function used by the data storage API 51 to obtain a hash value H2 of the construction status data supplied from the data storage 50.

Step S6_5: The quality and completed form confirmation program 61 reads the hash value H1 corresponding to the contract ID of the electronic contract for the construction to be inspected from the latest block of the blockchain.
Then, the quality and completed form confirmation program 61 compares the read hash value H1 with the hash value H2 that it created, and determines whether they are the same (match). If the hash value H1 and the hash value H2 are the same, the quality and completed form confirmation program 61 determines that the construction status data in the data storage 50 has not been tampered with.
On the other hand, if the hash value H1 and the hash value H2 are not identical, the quality and finished form confirmation program 61 determines that the construction status data in the data storage 50 has been tampered with.

Step S6_6: The quality and finished form confirmation program 61 reads the construction information management items described in the electronic contract for the construction to be inspected and the management values for evaluating the inspection target data of the construction information management items in the construction status data.
Then, the quality and finished product confirmation program 61 evaluates whether the inspection target data in the construction status data meets the control values (quality, standards, etc.), and outputs a quality flag indicating whether it is satisfied (OK (quality is met)/NG (quality is not met)) to the blockchain node 21, corresponding it to the contract ID of the block.

For example, the quality and finished form confirmation program 61 compares the construction status data with the control value, and calculates the construction error corresponding to the control value from the finished form of the construction.
For example, when the construction is earthwork in a construction project, the quality of the construction is judged by whether or not the error calculated between the actual measurement value obtained from the 3D point cloud of the completed form acquired by inspection of the construction target and the 3D shape model obtained from the design falls within the error range of the control value.
The quality and finished form confirmation program 61 sets the quality flag to OK when the calculated error is within the error range of the control value. On the other hand, the quality and finished form confirmation program 61 sets the quality flag to NG when the calculated error is outside the error range of the control value.

In addition, when the construction is earthwork in construction work, the quality and completed form confirmation program 61 calculates the completed form as a percentage indicating what percentage of the area of the completed form is relative to the requested area, or as a percentage indicating what percentage of the number of times the rollers are compacted relative to the requested number of times.
Then, the quality and completed form confirmation program 61 transmits the quality flag and completed volume to the blockchain node 21 as execution condition data.
When the blockchain node 21 receives a contract ID and execution condition data from the inspection system 60, it writes the execution condition data to a block of the blockchain in correspondence with the contract ID.

Step S6_7: In order to check the completed form of the construction requested from the contractor, for example, the inspector outputs the contract ID of the electronic contract for this construction to the inspection system 60 from the user terminal via a Web browser.
The quality and finished product confirmation program 61 outputs the quality flag and finished product amount corresponding to the contract ID entered by the inspector to the result viewing viewer 62 .

Step S6_8: The result viewing viewer 62 reads out image data of the captured image (image captured by an imaging device or the like) of the completed form of the construction target in correspondence with the contract ID.
The result viewing viewer 62 then displays the quality flag and execution condition data of the completed work volume, as well as a captured image of the completed form of the construction target, on the display screen of the user terminal via a Web browser.
Here, for example, when the construction is land development work, as described above, the result viewing viewer 62 superimposes in a virtual space the three-dimensional shape of the actual measured surface based on the three-dimensional point cloud of the finished form and a three-dimensional model of the finished form generated from the design data, and displays an image of the superimposed three-dimensional shape observed from any angle on the display screen, allowing the inspector to view the shape of the finished form relative to the shape in the design.

As described above, the client writes the execution condition data to the blockchain by comparing the measurement data corresponding to the construction information management items in the construction status data entered by the contractor, who is the builder, with the management values listed in the execution conditions. This improves traceability in managing the quality, finished form, and progress of each construction project, and enables inspection via the network, reducing the number of on-site inspections conducted by both the client and the contractor in the construction project in response to the construction status, and enabling inspection of the finished form and quality of the construction in real time.

<Process #7: Payment processing for construction work using smart contract>
The smart contract 30 determines whether the execution condition data satisfies the execution conditions in the electronic contract for each contract ID in the block of the blockchain.
Then, if the execution condition data satisfies the execution conditions in the electronic contract, the smart contract 30 transfers the value of the payment from the site address of the orderer listed in the electronic contract corresponding to the contract ID to the site address of the contractor (i.e., pays the payment for the construction work).
In addition, the smart contract 30 generates a transaction corresponding to the contract ID each time a payment is made for construction work.

As described above, the smart contract 30 compares the execution condition data requested by the inspection system 60 with the execution conditions in the electronic contract, and transfers the value as the consideration stated in the electronic contract from the site address of the orderer to the site address of the contractor, for example, as payment for the amount of work completed or for a preset payment date. Therefore, depending on the inspection results of the construction status at any stage (or timing), it becomes possible to pay the amount of work completed at a specified construction status.

Traditionally, the contractor received payment for the construction work only if the client's inspection determined that the completed form and quality of the work conformed to the execution conditions set out in the contract.
However, the client does not inspect the construction status at all times. In most cases, the payment for the construction is made upon completion of the inspection, or based on the results of inspections conducted at long intervals.
Large-scale construction companies are able to receive the funds necessary for construction work from banks and other sources, and are therefore able to carry out construction work in a format in which they receive payment at each designated construction stage.

On the other hand, among subcontractors such as first-tier, second-tier, and third-tier subcontractors, small businesses that specialize in specific tasks may be unable to prepare the funds for the work they have contracted out depending on the scale of the work if the payment cycle for construction work is long, and may be unable to participate in the construction work.
However, according to this embodiment, since payment can be made according to the construction status at any stage of the construction, even subcontractors such as second-tier and third-tier subcontractors who have a small business scale, lack financial resources, or have difficulty raising funds can undertake construction work.

<Process #8: Writing process of construction process history to database 40>
Metadata of the construction status data or log data in the creation of an electronic contract is written in the database 40 in correspondence with the contract ID and the block ID.
In other words, the smart contract execution API 12 writes and stores the request data in the request from the front end 11 and the response data supplied from the blockchain smart contract 30 in the database 40, corresponding to the block ID of the block in which the created electronic contract was created and the contract ID of this electronic contract.

In addition, when the data storage API 51 writes a hash value into a block of the blockchain, it writes and stores in the database 40 metadata that is specified in advance in the construction status data, in association with the block ID supplied from the blockchain node 21 at this time and the contract ID of the construction status data from which the hash value was created.

<Process #9: Information Acquisition Process from Data Storage 50 During Maintenance>
Step S9_1: The maintenance manager (user #3), for example, inputs a contract ID into a web browser on the user terminal, and performs processing to refer to the history in the database 40 corresponding to this contract ID.

Step S9_2: The maintenance manager extracts from the history corresponding to the contract ID in the database 40 the block ID of the block in which processing was performed that contains construction status data for the construction of the electronic contract corresponding to this contract ID.

Step S9_3: The maintenance manager transmits a search request for searching for construction status data corresponding to the contract ID and block ID to the storage 52 via the web browser of the user terminal.
In the data storage 50, the data storage API 51 searches the storage 52 for construction status data corresponding to the contract ID and block ID supplied from the user terminal.

Step S9_4: The data storage API 51 transmits the construction status data retrieved from the storage 52 using the contract ID and the block ID to the user terminal.
The maintenance manager views the construction status data corresponding to the contract ID and block ID supplied from the data storage 50 on the display screen of the user terminal.

As described above, the maintenance manager can extract the block ID of the construction status data to be searched for in the data storage 50 using the metadata corresponding to the contract ID in the database 40, making it easy to search for the construction status data in the data storage 50.
In addition, with the above-mentioned configuration, it is possible to detect whether or not the construction status data in the data storage 50 has been tampered with by the hash value of the construction status data in the blockchain, which not only manages the progress of construction work, but also improves traceability in maintaining and managing structures according to the quality and finished form of the construction after construction.

<Process #10_1: Process of writing design data to data storage 50 by client>
Step S10: User #1 (client) inputs design drawings of the construction site to be inspected, three-dimensional CAD (computer aided design) data, and the like, into a web browser on the user terminal.
As a result, design drawings of the construction site to be used for inspection, three-dimensional CAD data, and the like are input to the data storage 50 via the web browser.

Step S10_2: In the data storage 50, the data storage API 51 creates a hash value H1 of design drawings and 3D CAD data of the construction site to be used for inspection, which are supplied from the web browser of the client's user terminal, using a predetermined hash function.
Then, the data storage API 51 transmits to the blockchain node 21 the hash value H1 of the design drawings and 3D CAD data of the construction site to be used for the inspection, and the contract ID corresponding to the construction.
The blockchain node 21 writes the hash value H1 supplied from the data storage API 51 into a specific block in association with the contract ID, and transmits this block ID to the data storage 50.

Step S10_3: The data storage API 51 writes and stores actual data, such as design drawings and 3D CAD data of the construction site to be used for inspection, input from the web browser on the client's user terminal, in the storage 52 in association with the contract ID and each of the block IDs from the blockchain node 21.

In addition, with the above-mentioned configuration, it is possible to detect whether or not actual data such as blueprints and 3D CAD data of the construction site used for inspection in data storage 50 has been tampered with by the hash value of the actual data such as blueprints and 3D CAD data of the construction site used for the inspection in the blockchain, thereby improving the reliability of the inspection results using blueprints and 3D CAD data of the construction site used for inspection.

In the present embodiment described above, the smart contract 30 pays the consideration by transferring value (virtual currency) from the orderer's wallet to the contractor's wallet in accordance with the execution condition data based on the inspection results written in the blockchain.
However, when the smart contract 30 records the inspection results of the construction status on the blockchain, the smart contract 30 may be configured to send information about the inspection results to the user terminals of the client and contractor in the construction contract relationship corresponding to the contract ID.

In this case, the customer checks the construction inspection results in the corresponding blockchain from a user terminal and prompts the construction contractor to issue a construction invoice corresponding to the amount in the electronic contract for the corresponding contract ID.
Then, in response to the invoice issued by the contractor, the client pays for the construction work in the amount stated in the contract (the value to be paid is made by bank transfer or bill settlement using legal tender, for example Bank of Japan notes (yen)).

The orderer performs a process of writing the amount paid by the customer from the user terminal and the contract ID for this construction in the data storage 50.
As a result, the data storage API 51 writes the hash value of the payment to the blockchain as a transaction via the blockchain node 21, and writes the actual data related to the payment to the storage 52 for storage.

In addition, when the results of the inspection of the construction status are recorded in the blockchain, the smart contract 30 may be configured to send a confirmation request to the user terminal of the orderer as to whether or not it is acceptable to pay the price for the construction corresponding to the contract ID since the results of the inspection have been recorded.
In this case, the confirmation request screen has a button to allow payment, and the construction inspection results are checked in the corresponding blockchain. If it is acceptable to make payment, the allow button is clicked.
Then, when a button permitting payment of the consideration for the construction is clicked, the smart contract 30 makes payment by transferring value (virtual currency) from the customer's wallet to the contractor's wallet.

FIG. 4 is a block diagram showing a practical example of a construction information management system according to an embodiment of the present invention.
In FIG. 4, an orderer user terminal personal computer 101_1 corresponds to the user terminal used by user #1, the orderer, in FIG. 3, and has a Web browser application software installed therein.
The orderer user terminal personal computer 102_2 is a computer on which the orderer, user #2 in FIG. 3, checks the inspection and finished form based on the construction status data, and has a web browser application software installed therein.

The prime contractor user terminal personal computer 102 corresponds to the user terminal used by User #1 (prime contractor) who is the orderer and the recipient in FIG. 3, and has a Web browser application software installed.
The X-tier subcontractor user terminal computer 103 corresponds to a user terminal used by user #1 (an X-tier subcontractor including a first-tier subcontractor who undertakes construction work after the prime contractor) who is the orderer and contractor in FIG. 3, and has a web browser application software installed.

The maintenance manager user terminal PC 104 is a computer that allows user #3, the contractor who actually performed the construction work, to access the memory database 501 and writes construction status data showing the status of the construction work to the memory (for construction data) storage 502 via the construction management system 220, and has a web browser application software installed.

Each of the blockchain nodes 201 is a computer (including a personal computer (so-called PC)) or a server, and each is connected in a PtoP form to form a PtoP network 200. This PtoP network 200 corresponds to the PtoP network 20 in FIG. 3.
The smart contract execution application server 301 corresponds to the functions of the application 10 in Figure 3, and application software having the functions of the front end 11 and the smart contract execution API 12 is installed.

The smart contract program terminal computer 302 generates the application software program for the smart contract 30 shown in FIG. 3 and transmits it to the blockchain node 201 of the PtoP network 200. As a result, the blockchain node 201 loads the smart contract 30 into the blockchain it generates.

The database and data storage access server 303 is a server that accesses the storage 52 and the database 40 in FIG. 3, and has application software for the data storage API 51 and application software for accessing the database 40 installed therein.
3. Moreover, the storage unit database 501 corresponds to the database 40 in FIG.
The storage unit (for construction data) 502 corresponds to the storage 52 in FIG. 3, and is a storage unit in which the construction status data in the storage 52 is written.
Similarly, a storage unit (for design data) 503 corresponds to the storage 52 in FIG. 3, and is a storage unit in which design drawings of the construction site used for inspection in the storage 52, three-dimensional CAD data, and the like are written.

The application server 304 for executing graphic and numerical processing is a server in which the quality and finished form confirmation program 61 (application software) in Figure 3 is installed, and when this application software is started, the operation of the finished form confirmation program 61 in Figure 3 is executed.
In the viewer server 305, application software of the result viewing viewer 62 in FIG. 3 is installed, and the operation of the result viewing viewer 62 in FIG. 3 is executed by starting this application software.

In addition, a program for implementing the functions of the application 10, smart contract 30, and data storage 50 in FIG. 3 in the present invention may be recorded on a computer-readable recording medium, and the program recorded on the recording medium may be read into a computer system and executed to perform processing for managing construction work information using blockchain. Note that the term "computer system" here includes hardware such as an OS (Operating System) and peripheral devices. The term "computer system" also includes a WWW (World Wide Web) system equipped with a homepage providing environment (or display environment). The term "computer-readable recording medium" refers to portable media such as flexible disks, optical magnetic disks, ROMs (Read Only Memory), and CD-ROMs (Compact Disc - Read Only Memory), and storage devices such as hard disks built into computer systems. The term "computer-readable recording medium" also includes those that hold a program for a certain period of time, such as volatile memory (RAM (Random Access Memory)) inside a computer system that becomes a server or client when a program is transmitted via a network such as the Internet or a communication line such as a telephone line.

The above program may also be transmitted from a computer system in which the program is stored in a storage device or the like to another computer system via a transmission medium, or by transmission waves in the transmission medium. Here, the "transmission medium" that transmits the program refers to a medium that has the function of transmitting information, such as a network (communication network) such as the Internet or a communication line (communication line) such as a telephone line. The above program may also be one that realizes part of the above-mentioned functions. Furthermore, it may be a so-called difference file (difference program) that can realize the above-mentioned functions in combination with a program already recorded in the computer system.

10...Application 11...Front-end 12...API for smart contract execution 20...PtoP network 21...Blockchain node 30...Smart contract 40...Database 50...Data storage 51...API for data storage 52...Storage 60...Inspection system 61...Program for quality and completed form confirmation 62...Viewer for viewing results 101_1...Purchaser user terminal computer 101_2...Orderer user terminal computer 102...Primary contractor user terminal computer 103...Xth subcontractor user terminal computer 104...Maintenance manager user terminal computer 302...Terminal computer for smart contract program 301...Application server for smart contract execution 304...Application server for graphic and numerical processing execution 305...Viewer server

Claims (3)

A construction information management system that manages construction status data showing the status of construction work based on electronic contracts between clients and contractors of each layer of contract relationship in construction work,
a smart contract implemented on a blockchain and creating the electronic contract on the blockchain;
and a data storage application program interface (API) that writes and stores construction status data indicating the status of the construction in a storage in correspondence with a contract ID that identifies the electronic contract , and writes a first hash value of the construction status data in correspondence with the contract ID to the blockchain;
Further comprising an inspection system that corresponds to an inspection rule described in the electronic contract, inspects the construction status data, and writes the data to the blockchain as execution condition data in correspondence with the contract ID;
A construction information management system characterized by evaluating whether the inspection target data in the construction status data meets a control value, corresponding a quality flag indicating whether the quality is met to the contract ID, and outputting the quality flag to a blockchain node . The construction information management system according to claim 1 , wherein the construction volume is output to the blockchain node together with the quality flag as the execution condition data. A construction information management system as described in claim 1 or claim 2, wherein when the inspection system performs an inspection of construction using the construction status data, it calculates a second hash value of the construction status data read from the storage, compares the second hash value with the first hash value, and determines whether the construction status data has been tampered with.

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