Ontology for Querying Heterogeneous Data Sources in Freight Transportation

Abstract

Navigating through multiple heterogeneous freight data sources to find the ones that are relevant to answering a question can be a challenging task when performed manually. It is highly dependent on the individual’s knowledge of all available data sources and the information contained in each one. Multiple factors contribute to freight data heterogeneity, including differences in data element definitions, level of disaggregation, and classification systems. This paper proposes a standardized knowledge representation of freight data sources using an ontology that both computer systems and domain experts can understand. The ontology is developed from a formal representation of data elements found to exist in freight data sources. The paper also presents a querying algorithm for searching through the ontology and determining relevant freight data sources that can be used for answering user queries. The proposed ontology and querying algorithm facilitate the querying and identification of relevant freight data sources without the need for an extensive knowledge of the contents and organization of each data source. Issues relating to semantic heterogeneity inherent in freight data elements and gaps in existing freight data sources are also identified through the use of the ontology and querying algorithm.