Open data is generally defined as data that is publicly accessible and free to use. According to The Open Definition [1], to be truly open, data must be published under an open license that allows anyone to access, use, modify, and share it for any purpose. In addition, the data should be structured in a machine-readable and open format so that it has no restrictions and can be fully processed with a free software tool.

The open data market is constantly growing and various studies show that its value is rising steeply — not only in Europe, but all over the world [2,3]. In the European context, the availability of open data is strongly encouraged and there are regulations and directives in place to ensure the highest possible quality of data. Most European countries, as well as some major European cities, have their own national portals where they publish data from their public services (examples [4,5,6,7,8]). The official portal for European data [9] collects information from national portals and conducts research and comparative analysis. The value of the open data market in Europe was estimated at 184 billion euros in 2020 and is expected to reach between 199 and 334 billion euros by 2025 [2]. Open data includes not only open government data, but also open data from the private sector, and has even greater potential when combined with shared or personal data. It is worth noting that the value of data is not in the data itself, but in the value of the products, services, and content that open data enhances or enables. This reuse of data is encouraged not only in public services but also in private companies.

A study by Huyer and van Knippenberg suggested that the value of open data can be understood by examining the economic impact of its reuse. They propose a methodological approach to macro- and microeconomic estimates, with macroeconomic estimates involving quantitative analysis based on gross domestic product (GDP) estimates and microeconomic estimates providing quantitative analysis based on company- or individual-level data. The authors have adapted and applied the methodology to different areas — market size, job market, sectors, efficiency, costs saved, and organisations. Analysing available data and incorporating the results into services and products based on or enriched by open data can lead to indirect economic benefits, i.e. efficiency gains. The latter often also reflect societal benefits, for example when it comes to saving time on various tasks such as commuting via public transport or in traffic, saving lives, or helping the environment.

Open data on routes, departure times, delays and other relevant information can help to optimize public transport. By providing accurate and reliable real-time information through apps on personal devices, people can anticipate potential delays, adjust their route choices and optimize their travel time. For example, being informed of a delay before departure can reduce the actual waiting time for each train delay by an average of 2 minutes per person [2]. If all passengers in Europe used such apps, the researchers estimate that 27 million hours could be saved annually. This not only saves time, but also increases passenger satisfaction with public transport. Greater satisfaction can potentially increase people’s willingness to choose public transport over private transport and thus promote a more environmentally friendly alternative. Real-time information reduces both actual and perceived waiting times, which has a significant impact on overall satisfaction with public transport services [10].

The methodology of [2] was a basis for the study of the economic-social impact of open data in Slovenia by Likar and Štrukelj. The study revealed an estimated potential of 93 million euros for the size of the Slovenian open data market by 2025. In terms of efficiency in public transportation, it was estimated that providing real-time information about public transportation with open data-based apps can help save 97 thousand hours annually for all Slovenian train travelers. Based on the average labor costs per hour, open data can potentially save 1.85 million euros through time savings in public transport in Slovenia.

Slovenia has been actively working with open data since 2015 and, according to the Open Data Maturity (ODM) assessment in the context of the EU27, market maturity is continuously rated as above average. In addition to the quality of metadata, the ODM assessment also evaluates the level of national policies promoting open data, the features of national data portals, and initiatives to monitor the reuse and impact of open data [12].

Although some data are narrowly domain-specific, a significant part of open data has wide applicability in everyday life. However, the current form in which data is published often poses challenges for non-professional individuals. It may require prior computer knowledge for processing the data and may not be suitable for opening in freely available tools (e.g. due to the size of the CSV files). To address these challenges, efforts to improve the accessibility and usability of open data have led to the development of various applications that source data from open data portals and present it to users in a more user-friendly form.

In developing models for public transport and mobility services data in Slovenia, the focus was on the following important steps:

The pipeline for Avtolog.si was comparatively less complex as it relied on a single data source, so there was no need for format unification. All available vehicle data based on vehicle identification numbers (VINs) is collected by the Slovenian Open Data Portal [22]. When designing the application to present this data in a visually appealing and user-friendly format, the information that is most relevant to potential users (car owners and buyers) was selected, namely mileage and age of the owner, which are highlighted in the application, while the others are divided into four categories – vehicle information, technical inspections, information about the owner, and history. The frontend of the application was developed with React, which provides a dynamic and responsive user interface. The backend is powered by Django, a sophisticated Python-based web framework. For data storage and analysis, Avtolog uses Elasticsearch, a RESTful search and analytics engine, coupled with Kibana for data visualization.

The applications have overcome various challenges in combining different formats of multiple data collections and helped to close the gap in the reuse of mobility and transportation data in Slovenia. Their primary advantage is that they are free to use and some even offer APIs that support developers in creating new solutions. The multimodal transportation applications offer several advantages that improve the user experience and promote sustainable urban mobility. Features such as customizable filters ensure a personalized and efficient experience. Real-time public transport tracking provides live updates on bus locations and timetables, allowing passengers to plan their journeys accurately and avoid unnecessary waiting times. Future developments could include the integration of comprehensive route planning features, allowing users to plan journeys using all or selected modes of transport. The Breazavta app is already in beta testing for this feature. In addition, there are plans to introduce a sustainability calculator that will calculate the carbon footprint saved by choosing sustainable transportation options. This feature could encourage users to make more environmentally conscious decisions by visualizing their positive impact on the environment.

The Avtolog application increases transparency in the used vehicle market by linking national vehicle registration data with technical inspection data, thus increasing safety, also at European level. The application supports informed decision-making when buying a pre-owned vehicle by providing detailed information on the safety and technical condition of vehicles. By allowing users to search for information on individual vehicles, it helps them to become better informed and reduce the risk of fraud. When transferring ownership of a used car, the condition of the vehicle is crucial to the current price and future investment. The depreciation of a vehicle is mostly based on the kilometers driven, and the average mileage varies greatly depending on the form of ownership, location and intended use (leasing or ownership, Slovenia or abroad, private or business use). Therefore, the number of kilometers driven is an important factor that future owners consider when purchasing a vehicle. The most common cases of fraud include manipulated odometers, the installation of non-homologated parts, and deception regarding use and ownership. In addition, the app highlights environmental and safety aspects, such as the number of vehicles with different drive types and the EURO standards of petrol and diesel engines. By providing comprehensive data on pollutant emissions and EURO standards, the app raises users’ awareness of environmental impacts. Possible future enhancements to Avtolog include the systematic addition of new sources to the database in order to obtain additional vehicle information. For example, a connection could be established with the database of stolen vehicles and information on the payment of road tax could be included. Cooperation with neighboring countries would also enable a comprehensive check of the history of imported vehicles and address the common problem of odometer tampering. A notable limitation to data collection is the current legislation, which does not require the first mandatory technical inspection until four years after the vehicle is first registered. As current legislation does not regulate the inspection or recording of the condition of newer vehicles, this should also be taken into account. Systematically recording the mileage at each vehicle service and reducing the time interval for reporting the data from one year to one month could provide users with more accurate and up-to-date data. The application could also be enhanced by including other existing information, such as reasons for technical inspection failures, which could improve the accuracy and scope of the application.

Overall, future work on such applications should also focus on calculating their socio-economic impact. By collecting and analyzing real-world usage data, information on delays, trends in vehicle history and other relevant statistics, researchers can go beyond speculative estimates and make more accurate and realistic assessments. For example, time savings from the introduction of real-time public transportation apps can be more accurately estimated by examining data on current delays and user behavior. Other benefits could also be identified, such as less traffic congestion, lower emissions, and better air quality through the optimized use of public transport or bike sharing services. In addition, by analyzing trends in vehicle data, we can examine potential impacts on the used car market. If vehicle data is made openly available in a user-friendly format, this could lead to less odometer tampering. If trends in newer entries show less tampering, this suggests that open data can improve market transparency. This approach not only helps to demonstrate the immediate benefits, but also supports long-term planning and policy making to maximize both economic and social benefits.

We have presented applications that exemplify best practices in the use of open data for mobility and transportation in Slovenia. While public and multimodal transport services are developed and widely used in other European cities, the Slovenian public transport network was not significantly considered before the development of these applications. In addition, integration with commercial services such as car sharing makes sustainable transportation options even more accessible to users. A notable example of the use of open data is also a free service for vehicle history report, all based on vehicle identification number. This application is a valuable tool for all drivers, especially those considering purchasing a used car. The paper also discusses strategies for dealing with the challenges associated with large and diverse datasets and provides useful advice for developers facing similar problems. Such projects demonstrate the successful application of big data collections to simplify and enhance people’s lives. They show the potential for future projects in other countries to use open data for the benefit of the general public.