# Urban Expressway Renewal Strategy Based on Knowledge Graphs
## 3 Materials and Methods  
In this paper, we designed reasoning rules based on road maintenance-related standards, combine cosine similarity, and use a knowledge graph as a carrier to precisely match reasonable renewal solutions for expressways through knowledge reasoning and case similarity to provide a strategic reference for urban infrastructure renewal. According to the description of knowledge graphs from the perspective of a directed graph by scholars [12; 13], the knowledge graph of urban road renewal in this paper can be defined as \(G=<E\), \(R\), \(P\), \(U>\), where \(E\) stands for entity set such as city, urban expressway, and pavement energy condition; \(R\) stands for the set of relationships among entities; \(P\) is the entity property value in the form of numerical value, string, etc. ; and \(U\) stands for the reasoning rule set. In knowledge graph \(G\), facts in triplet form are formed by (\(E\), \(R\)) and (\(E\), \(P\)), and finally form the rich knowledge network in the knowledge graph. We constructed the knowledge graph of urban road renewal first, and the specific implementation process is shown in Figure 1. To model urban road renewal based on multi-source data, this paper adopts ontology as the data model, builds a conceptual model of urban road renewal based on the existing ontology knowledge base, and refers to the standards and guidelines related to urban road renewal. Then, focusing on urban expressway renewal, we populated the collected expressway related data and stored the graph data with the help of the neo4j graph database to realize visualization. On this basis, SWRL (Semantic Web Rule Language) reasoning rules for expressway renewal decisions were designed to realize the intelligent decision of expressway renewal by the combination of logical rule reasoning and case similarity. In Figure 1, to enhance the interoperability of the knowledge graph of urban road renewal and realize the integration and sharing of knowledge, this paper used the existing ontology knowledge base as one of the bases of the conceptual model, and extracted reusable concepts and relations from the existing ontology to enrich the conceptual model of urban road renewal. In the construction and implementation of the knowledge graph, ontology was used as the realization method to build the road renewal ontology knowledge base through the ontology automation strategy. The knowledge base integrated the concepts and knowledge into the existing ontology, and provided the conceptual framework and basic terminology knowledge for the urban road updating knowledge graph. Figure 1: Implementation of knowledge graph for urban road renewal. To provide a basic conceptual framework for the construction of the knowledge graph, this paper used the urban renewal guidelines and industry standards as references. Specifically, the standards of 'Technical specifications for maintenance of highway asphalt pavement' (JTG 5142\(-\)2019) and 'Technical specifications for preventive maintenance of highway asphalt pavement' (JTG/T 5142\(-\)01\(-\)2021) provide a large amount of road maintenance-related knowledge, especially the content related to road diseases and corresponding disease treatment measures, which provides rich knowledge material for this research on expressway renewal. These two standards specify the main types of road maintenance, such as preventive maintenance, repair maintenance, and emergency maintenance, as well as road diseases such as crack type, deformation type, and surface damage type. Based on these entity types, the conceptual model of expressway renewal is studied in this paper. The main concepts and properties extracted from the two standards are shown in Figure 2.  
Based on Figure 2, this paper further abstracted the road maintenance-related concepts and describes them with various categories and road properties to lay the foundation  
Figure 2: Road-related concepts and indexes extracted from the standards. for establishing a knowledge system oriented to expressway renewal.