An Overview of Intelligent Transportation Systems in Europe

Abstract

This paper provides a comprehensive review of the development, deployment and challenges of Intelligent Transport Systems (ITSs) in Europe. Driven by the EU Directive 2010/40/EU, the deployment of ITSs has become essential for improving the safety, efficiency and sustainability of transport. The study examines how ITS technologies, such as automation, real-time traffic data analytics and vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communication, have been integrated to improve urban mobility and road safety. In addition, it reviews significant European initiatives and case studies from several cities, which show visible improvements in reducing congestion, reducing CO₂ emissions and increasing the use of public transport. The paper highlights, despite progress, major obstacles to widespread adoption, such as technical interoperability, inadequate regulatory frameworks and insufficient data sharing between stakeholders. These issues prevent ITS applications from scaling up and functioning well in EU Member States. To overcome these problems, the study highlights the need for common standards and cooperation frameworks. The research analyses the laws, technological developments and socio-economic effects of ITSs. By promoting sustainable and inclusive mobility, ITSs can contribute to the European Green Deal and climate goals. Finally, the paper presents ITSs as a revolutionary solution for future European transport systems and offers suggestions to improve their interoperability, data governance and policy support.

1. Introduction

1.1. The Necessity of the Proposed Topic

Intelligent transport has a significant impact on urban and regional mobility, and is a continuously changing area of modern infrastructure. The present study reviews Intelligent Transport Systems (ITSs) in Europe and analyses their progress, challenges and benefits. ITSs are essential for optimizing transport flows, reducing emissions and improving road safety in today’s world, characterized by sustainability objectives and accelerated urbanization. Several studies have examined the development and implementation of Intelligent Transport Systems (ITSs) in Europe, focusing on various aspects such as standardization, technological evolution, policy frameworks and crossnational comparisons.

Festag (2014) provided a comprehensive overview of the standardization process for Cooperative ITSs (C-ITSs), highlighting how a decade of research and development enabled the launch of connected mobility services [1]. The role of European standardization organizations—the European Committee for Standardization (CEN), the European Committee for Electrotechnical Standardization (CENELEC) and the European Telecommunications Standards Institute (ETSI)—in shaping ITS technical and legal frameworks was further emphasized in a historical analysis published by Nowacki (2012) [2]. Duan (2023) compared ITS standardization policies between Europe and the United States, underscoring the effectiveness of Europe’s policy-driven approach [3]. The European Commission’s Directorate-General for Mobility and Transport has also documented the importance of ITSs for job creation and innovation, noting the growing influence of technologies such as AI, 5G and blockchain.

These studies have laid critical groundwork; however, they often focus on isolated topics such as technical standards, historical development or single-country policies. In contrast, the present paper offers an integrated and updated review that examines ITSs in Europe from multiple perspectives—technological, legislative and strategic—while also incorporating case studies and policy implications.

1.2. Contribution to Current Research

Through its holistic approach, the present paper is intended to support both academic research and policymaking for smart and sustainable mobility in Europe. The main objective of this research is to examine how ITSs have changed European transport by providing advanced technological solutions to current mobility challenges. The study examines European legislation, the adoption of ITSs in different Member States and the effects on sustainability, road safety and transport efficiency. This analysis attempts to find the essential elements that contribute to the success of ITSs, as well as the problems that hinder their wider and uniform implementation.

To better picture the connections between different factors and the main topics addressed through the present paper, the figures shown are AI-generated based on the authors’ input in the napkin.ai open access software (Version beta 0.13.2).

The research hypotheses provide a theoretical basis for the study, opening the path to analyze and interpret the research (Figure 1). In this context, it is believed that Intelligent Transportation Systems (ITSs) improve urban mobility by reducing congestion and increasing traffic efficiency.

Furthermore, ITSs are considered essential for improving road safety, as solutions such as vehicle-to-infrastructure (V2I) and vehicle-to-vehicle (V2V) communication have the potential to significantly reduce the number of road traffic crashes. However, the implementation of ITSs faces numerous obstacles, such as technical, legislative and economic ones. These obstacles are mainly caused by the lack of a framework to standardize and interoperate between different technologies. Furthermore, an important element of this research is the relationship between ITSs and the EU’s sustainability objectives, as these systems help to reduce environmental impacts by optimizing routes and encouraging the use of public and alternative transport.

These hypotheses constitute the analytical basis of the study, which was evaluated by examining European legislation, the initiatives implemented for ITSs and their effects on transport and the environment.

1.3. Structure of the Paper

The main issues addressed in this article, which represent the aims of the review, are presented in Figure 2.

The objectives of this study are as follows:

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To examine the historical evolution of Intelligent Transport Systems (ITSs) and assess the impact of Directive 2010/40/EU on the European legislative framework, with a focus on how regulations and policies have supported ITS implementation;

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To identify the essential components of ITSs and analyze their role in optimizing transport, particularly technologies such as automation, artificial intelligence (AI) and vehicle-to-infrastructure (V2I) communications;

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To analyze the main European initiatives that support ITS development and evaluate their influence on road safety, urban mobility and environmental sustainability;

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To investigate the obstacles and challenges in ITS implementation, including technical, legislative and economic issues, based on relevant case studies that highlight successful practices and lessons learned;

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To explore future trends and development plans for ITSs in Europe, and to propose recommendations for improving the efficiency and interoperability of systems to support digitalization and sustainability goals.

A qualitative document analysis was employed to identify and synthesize relevant regulations, strategies and academic sources related to Intelligent Transportation Systems (ITSs) in Europe. Key legal documents—such as EU directives, communications and funding frameworks—were retrieved primarily from EUR-Lex and official European Commission repositories. The relevant scientific literature was selected through searches in Scopus, Google Scholar and Web of Science, using keywords such as “Intelligent Transport Systems”, “ITS regulation Europe”, “C-ITS”, “V2X policy” and “sustainable mobility EU”.

The selection criteria focused on sources published between 2010 and 2024, prioritizing materials that addressed regulatory developments, cross-border implementation challenges and real-world ITS applications in EU Member States. Documents and articles were included if they provided substantial insights into governance, technological architecture, interoperability or deployment outcomes.

The proposed structured approach ensures that the findings reflect both the legislative evolution and the practical integration of ITSs across diverse European contexts.

This study provides additional value due to its in-depth and comprehensive analysis of the evolution, impacts and challenges of ITSs in Europe. It represents an integrated perspective on how technological developments, legislative frameworks and sustainability objectives interact with each other, with strategic implications for public policies and the future development of intelligent mobility. The study therefore offers useful information for researchers, transport authorities, policymakers and industry to help create a more efficient and sustainable transport environment.

2. A Brief History of ITSs in Europe

In recent decades, there has been a significant increase in the use of ITSs due to the high demand to improve the safety, efficiency and sustainability of transport in Europe. These systems use modern communication and information technologies to improve traffic management, reduce environmental impacts and increase road safety [4]. The adoption of Directive 2010/40/EU marked an important step in the formalization of ITSs in the EU. It established a framework for the coordinated deployment of ITS applications in all Member States. The aim of this Directive was to help ITS technologies work together across Europe [5].

ITS technology has changed the way transport in Europe has evolved, as shown in Figure 3. This highlights the importance of Cooperative Intelligent Transport Systems (C-ITSs), autonomous vehicles and the Internet of Things (IoT) in increasing operational efficiency, safety and traffic flow.

C-ITSs enhance traffic flow, reduce congestion and increase road safety by facilitating V2I and V2V communication. The dynamic management of transportation networks and sharing of real-time traffic data are possible due to this connectivity [6].

Autonomous vehicles operate without human intervention using sophisticated sensors, machine learning algorithms and artificial intelligence. By optimizing traffic flows, reducing crashes and facilitating access for people who cannot drive, these types of vehicles have the potential to change the way transportation is carried out [7].

Thanks to technologies embedded in the Internet of Things, data can be collected and analyzed from various sources, such as mobile devices, infrastructure and vehicles. This data-driven approach facilitates real-time decision-making, such as optimizing transportation operations and the predictive maintenance of infrastructure [8].

ITSs were initially developed to address road traffic congestion and rising emissions in Europe. Research initiatives and pilot projects investigated the integration of transport systems with information and communication technology (ICT) in the 1990s. These efforts laid the foundation for the development of dynamic traffic management systems as well as real-time data-driven decision-making systems [9].

Directive 2010/40/EU marked an important step in the regulation of ITSs in Europe. It highlighted the importance of collaboration between Member States, industry stakeholders and public authorities to ensure that ITS applications are implemented in a coherent and coordinated manner. Road safety, congestion reduction and reductions in pollutant emissions were the main priorities of the Directive [10]. The Directive initiated a series of programs to encourage the deployment of ITSs in European regions. For example, the Euralille 3000 project used ITSs in urban areas to enhance traffic monitoring and public transport organization, and to improve the quality of life in the city [11].

In addition, the European Union has prioritized vehicle-to-infrastructure communication technologies, which facilitate seamless interaction between vehicles and road traffic management systems. This advance in real-time data transfer has improved road safety and traffic flow management [12].

Consequently, a number of studies have examined in detail the development and strategic application of ITSs in Europe.

For example, Festag [1] examines the development of V2V and V2I communication standards. He shows how a decade of research and development, as well as pilot projects, paved the way for cooperative ITSs. This led to the finalization of C-ITS standards by 2014 and enabled the launch of connected mobility services in that year.

Furthermore, Nowacki [2] provides a historical overview of ITS in Europe, from the first research in telematics to the principles of modern ITS. He highlights the role of the European standardization organizations (CEN, CENELEC and ETSI) in creating a solid technical and legal framework for ITS applications in different transport domains.

Going on, Mitsakis et al. present the strategic vision of ITSs for safe, efficient and sustainable transport in Europe [13]. They examined how legislation such as Directive 2010/40/EU and the 2008 ITS Action Plans influenced national implementation, promoting interoperable and seamless services between Member States and improving the efficiency of international transport [14].

The study by Duan [3] examines ITS standardization in Europe and the United States between 1991 and 2012. Ultimately, Europe’s government-led and policy-based strategy has encouraged strong top-down cooperation and faster standardization among stakeholders. Europe’s proactive policies and cooperative frameworks have enabled the rapid integration of ITS. These frameworks underscore the importance of deliberate policy support in the growth of these technologies.

The European Commission’s Directorate-General for Mobility and Transport has highlighted the strategic importance of ITSs for creating new services and jobs in the transport sector by 2030. The report highlighted the importance of data sharing and digital technologies in improving the safety and efficiency of travel in Europe, which benefits all stakeholders, including governments, private companies and consumers [15]. As ITSs continue to evolve, the integration of emerging technologies such as 5G connectivity, artificial intelligence and the blockchain will further transform the transport landscape in Europe, making it more adaptable, safe and sustainable [16].

3. Key Components of Intelligent Transportation Systems

Intelligent Transport Systems comprise strategies and technologies designed to increase the sustainability, safety and efficiency of transport networks. To improve the user experience and optimize traffic management, these systems integrate both software and hardware modules [7].

ITS components are divided into hardware and software, as shown in Figure 4. Short-range IoT devices and wireless communications, as well as long-range infrastructure sensors that can be connected to smartphones, are part of the hardware. The platform includes data analysis platforms and traffic management applications. Through this integration, ITSs can improve mobility in cities.

A variety of devices designed to collect, process and transmit transport-relevant data are part of the hardware components of ITSs. These include a wide range of technologies, such as sensors, cameras, traffic signals, IoT-based transportation devices and vehicle detection systems, all of which are essential for the efficient operation of modern ITSs [8,12,17]:

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Sensors, cameras and traffic signals: Due to road conditions, vehicle movement and traffic flows, cameras and sensors collect data in real time. Smart traffic signals with GPS technology reduce congestion and manage dynamic traffic.

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IoT transportation devices: Road units, sensors, detection cameras and traffic light control devices are just a few of the IoT technologies that are widely used in ITSs. These devices are vital for traffic control systems and route optimization, as they collect real-time data on weather conditions and road traffic flow.

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Vehicle detection systems are aimed at tracking vehicles in critical areas using technologies such as electronic beacons, automatic license plate recognition and magnetic signature detection. Automatic incident detection and the monitoring of traffic flows at intersections and checkpoints require these software components of ITSs.

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ITS software processes and analyses data collected by hardware components, enabling real-time decision-making and the efficient management of road traffic. Road traffic management software enables the control of vehicle flows, optimization of routes and reductions in environmental impacts. They help with vehicle-to-everything (v2x) communication and adaptive traffic light control, respectively [6].

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Platforms that enable data analysis: By processing and interpreting data collected from traffic, data analysis platforms improve vehicle flows, increase safety and reduce environmental impact. These platforms help transport management to optimize road infrastructure [15].

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High-definition (HD) maps, which provide accurate and up-to-date geospatial data, are another vital part of ITSs. They are essential for autonomous driving, traffic control and vehicle-to-vehicle (V2X) communication. Currently, in Europe, a number of applications, including HERE HD Live Map and TomTom’s HD Map platform, are used to facilitate the localization and decision-making processes for autonomous vehicles. Compared to traditional maps, HD maps provide centimeter-level accuracy in identifying road geometry, traffic signs, lane markings and static objects [18]. In order to support level 4–5 autonomous systems and complex traffic management approaches, the integration of HD maps into ITS infrastructures is becoming increasingly important.

ITSs require the integration of mobility solutions and interoperability between different technologies. This is essential to facilitating a continuous flow of information between different means of transport. According to European Directive 2010/40/EU, interoperable systems that enable smooth communication between vehicles, infrastructure and other modes of transport are essential [5].

Figure 5 presents the main components of ITSs, as well as their roles in the process of collecting, transmitting and analyzing data to optimize urban mobility.

Public transport operators in local communities play a key role in organizing these systems. Users can access multiple modes of transport in a single application with Mobility as a Service (MaaS) platforms [16].

Moreover, ITSs offer a range of safety features to protect road users and optimize response in emergency situations. eCall is an automated system that, when a collision is detected, transmits information about a crash, including the location and identification of the vehicle, to the emergency services. This technology can save lives and significantly improve response times in road crashes [11]. In addition to eCall, ITSs also integrate other safety technologies. These include early warning systems and the prioritization of emergency vehicles at traffic lights. These technologies make transportation safer by reducing the number of crashes and their consequences [12].

Intelligent Transport System components play a critical role in transforming global transport infrastructure. The seamless integration of ITS hardware and software, along with their interoperability and advanced safety functionalities, contributes to creating a safer, more efficient and more sustainable transport environment.

4. Use of ITSs in Europe

4.1. Major ITS Initiatives

The European Union has recognized the importance of Intelligent Transport Systems (ITSs) in improving the safety, efficiency and sustainability of transport networks. The integration of road and rail networks helps facilitate sustainable means of transport such as cycling, scooters and walking [19]. This reduces emissions and improves quality of life in cities.

In Figure 6, the main ITS initiatives in Europe are symbolically represented in a concentric arrangement. The colors and positioning of the elements indicate the relative levels of relevance and strategic impact, without expressing quantitative values. Important ITS initiatives in Europe are grouped into categories such as innovation and societal challenges, legislative changes and significant initiatives. These groups contribute to driving the overall growth of ITSs in Europe.

To improve interoperability between systems and guarantee the integration of ITSs with different types of transport, Directive 2010/40/EU specifies the technical requirements and regulatory conditions for harmonized implementation in EU Member States [5].

Following extensive consultations with private and public stakeholders, the Committee of Ministers of the Council of Europe adopted a revised version of the Directive in 2023. The aim of the new regulation is to eliminate monopoly practices and facilitate seamless interoperability between different transport systems, creating a level playing field for ITS applications [20].

To accelerate the deployment of ITSs in Europe, the European Commission has launched a number of strategic initiatives. From the New European Innovation Agenda, which aims to place Europe at the forefront of cutting-edge technological innovation, these programs include the following [21,22]:

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Battery 2030+, which is an effort to position Europe as a leader in battery technology by developing high-performance, safe and sustainable batteries. Efficient batteries are essential for electric vehicles and cleaner economies.

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Graphene flagship, which reflects Europe’s commitment to improving materials science, exploring the applicability of graphene in various transport applications, such as sensors and lightweight materials for vehicles.

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Social challenges and innovation in ITSs: Addressing societal challenges such as sustainable mobility and social inclusion is closely related to the implementation of ITSs. Projects funded through the European Union’s Horizon 2020 program emphasize that transport solutions should be easy to use and accessible to everyone, regardless of age, gender or social status [21]. The incorporation of social innovations into ITSs underlines the European Union’s commitment to developing a transport system that meets the needs of all users, facilitating the mobility of people with disabilities and those belonging to disadvantaged communities [20].

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Cross-border collaboration and activities: For ITS projects to be successfully implemented, Member States, local governments and private sector stakeholders need to work together. However, legislative obstacles often hinder international trade, especially in areas where national regulations are strict [19]. The European Commission is addressing these issues by creating a single market for sustainable digital goods and services. This facilitates innovation and the integration of new business models into the ITS ecosystem [23].

Through these programs, Europe hopes to create a solid framework for Intelligent Transport Systems, which will not only improve transport efficiency, but also promote social equality and the environment. The future of European mobility is based on ITSs, which address inclusive transport solutions, efficient batteries and innovative materials.

4.2. Case Studies of ITS Use

To improve urban mobility and promote sustainability, ITSs should be deployed in European cities. The strategic plans of many municipalities are in line with the objectives of the European Green Deal and take into account local and global environmental factors.

As these systems reduce traffic, enable cleaner modes of transport and encourage modal shifts from private vehicles, they are essential for reducing carbon emissions [24].

ITSs improve the quality of life in cities by improving air quality, reducing noise pollution and making more efficient use of transport infrastructure. They also help support long-term climate goals and digital transformation strategies at the city level.

Table 1. Results achieved through implementation of ITSs in urban areas.

City, Country	Year of Implementation	Type of ITS Implemented	Investment [Million EUR]	Results Achieved
Berlin, Germany [25]	2021	AI-based traffic management	250	15% reduction in congestion
Paris, France [26]	2022	Smart parking systems	180	30% improved parking efficiency
Madrid, Spain [27]	2023	Autonomous bus fleet	200	20% reduction in commute time
Amsterdam, The Netherlands [28]	2021	Bicycle ITS integration	150	25% increase in cycling trips
Vienna, Austria [29]	2022	Smart pedestrian crossings	170	40% fewer pedestrian accidents
Milan, Italy [30]	2023	Real-time public transport tracking	190	10% increase in public transport use
Stockholm, Sweden [31]	2020	5G-enabled traffic signals	220	20% reduction in travel delays
Helsinki, Finland [32]	2021	AI-powered congestion control	230	18% lower CO2 emissions
Brussels, Belgium [33]	2022	V2I communication systems	210	Improved road safety by 25%
Lisbon, Portugal [34]	2023	Electric bus fleet expansion	260	30% reduction in fuel costs
Copenhagen, Denmark [35]	2021	Smart tolling system	240	10% increase in toll revenue
Prague, Czech Republic [36]	2022	AI-based transit scheduling	200	15% improvement in bus punctuality
Budapest, Hungary [37]	2023	Intelligent intersection control	180	12% decrease in traffic congestion
Warsaw, Poland [38]	2021	Smart highway system	250	20% improved traffic flow
Bucharest, Romania [39]	2022	ITS-integrated metro system	220	10% more metro users
Cluj-Napoca, Romania [40]	2023	Integrated smart transport systems (smart lights, e-ticketing, real-time info)	160	Enhanced urban efficiency and sustainability
Riga, Latvia [41]	2023	Electric tram modernization	210	15% energy savings
Tallinn, Estonia [42]	2021	Real-time urban mobility apps	190	20% improved transit efficiency
Vilnius, Lithuania [43]	2022	Smart pedestrian monitoring	180	30% reduction in pedestrian accidents
Sofia, Bulgaria [44]	2023	Intelligent traffic cameras	170	12% more effective law enforcement
Zagreb, Croatia [45]	2021	AI-based vehicle tracking	160	10% reduction in transport delays

presents a selection of European cities that have implemented ITSs of various types between 2020 and 2023. The year of implementation, the type of ITS solution chosen, the financial investment allocated (in millions of EUR) and the results achieved after implementation are all presented below. Examples include smart parking systems and traffic management based on artificial intelligence (Berlin) and autonomous bus fleets (Madrid), as well as the integration of bicycles into ITS infrastructure (Amsterdam).

The results show the benefits of ITSs for urban mobility, which include reductions in travel time, increases in the efficiency of public transport, reductions in CO₂ emissions and improvements in pedestrian safety. This information shows how important the strategic investment in the digitalization of urban transport is and how relevant it is for achieving the objectives of the European Green Deal.

Each city develops its plans according to the problems arising in the area, but they all have a common goal: the development of environmentally friendly, efficient and accessible transport systems.

For other cities in Europe seeking smart and sustainable mobility solutions [46], these examples can serve as models.

The implementation of Intelligent Transport Systems in European cities is a significant step towards sustainable urban mobility and reduced environmental impact. Case studies from several European cities have demonstrated how important it is for residents, corporations and governments to work together for such projects to be successful. As technology advances, European cities will need to change their approaches to fully exploit the potential of ITSs.

5. Key Features of ITSs

5.1. Benefits of ITSs

A wide range of benefits offered by ITSs significantly contribute to increasing the efficiency, safety and sustainability of transport networks across Europe. To address the challenges of accelerated urbanization, traffic congestion and environmental problems, these benefits are essential. To improve the user experience and optimize transport operations, ITSs use technologies such as AI and real-time data analytics [47].

Figure 7 shows the benefits of ITSs, which include reduced emissions and pollution; improved road safety by reducing the number of crashes; increased economic efficiency by optimizing traffic flow and reducing costs; improved mobility by increasing comfort and accessibility; and public health benefits by encouraging a healthier lifestyle and reducing stress.

5.1.1. Environmental Impact

ITSs can significantly reduce greenhouse gas emissions. Public transport has much lower emissions than individual motorized transport. This makes urban mobility account for around 40% of CO₂ emissions. ITSs encourage the use of public transport and reduce dependence on fossil fuels, thus reducing air pollution [48]. For example, a report by the European Commission [49] shows that the implementation of intelligent traffic management systems has reduced fuel consumption by 11%.

5.1.2. Improving Road Safety

The main objective of ITS development is to ensure road safety, aiming to reduce the number and severity of crashes. eCall, which speeds up emergency responses after crashes, and C-ITSs, which facilitate communication between vehicles and infrastructure, are examples of current approaches [50]. These innovations are likely to contribute to the EU’s goal of achieving zero road deaths by 2050 [51].

5.1.3. Economic Efficiency

Due to lost time and inefficient logistics, traffic congestion costs the European Union economy more than 1% of Gross Domestic Product (GDP) annually. By improving traffic management, reducing travel times and improving operational efficiency, ITSs improve economic competitiveness [52]. A report by the European Commission shows that ITSs can reduce travel times by 66% [53].

5.1.4. Improved Mobility

By efficiently coordinating different modes of transport, ITSs improve the travel experience. Prague is one of many cities where smart solutions, such as artificial intelligence-based traffic management systems, are improving the efficiency of urban transit while respecting historic infrastructure [54]. Travelers are empowered to make informed choices with the help of mobile applications that offer a variety of transport options, leading to the development of more environmentally friendly means of transport [55].

5.1.5. Public Health Benefits

Congested transportation not only wastes time, but also puts people at risk due to increased exposure to hazardous emissions. Traffic congestion increases the release of fine particulate matter (PM2.5), which can affect cardiovascular and respiratory systems [56].

Cities can improve air quality and promote healthier urban environments by reducing congestion through ITSs [57].

ITSs have played major roles in transforming transport networks in Europe. From reducing environmental impact and increasing road safety to improving economic efficiency and public health, ITSs represent integrated solutions to current and future challenges in urban and regional mobility.

5.2. Challenges and Obstacles in the Implementation of ITSs in Europe

In Europe, the deployment of ITSs faces a number of challenges and obstacles that prevent the widespread and effective implementation of these systems in all Member States. A number of technical, regulatory and operational issues are the sources of these problems. In order to accelerate technological progress in the field of transport, European-level solutions are needed to address the existing obstacles, despite the significant benefits that ITSs offer in terms of road safety, efficiency and sustainability [58].

5.2.1. Technical Interoperability Issues

The lack of technical interoperability between different Cellular Vehicle-to-Everything (C-V2X) solutions and existing technologies such as LTE-V2X (Long Term Evolution-based Vehicle-to-Everything) and 5G-NR VANET (Fifth-Generation New Radio Vehicular Ad Hoc Networks) is one of the main issues in ITS deployment. Currently, there is no common standard that facilitates the seamless integration of multiple systems and technologies, making large-scale deployment more difficult [59]. Furthermore, although essential, the principle of technological neutrality is not directly included in the ITS Directive; rather, it is the responsibility of the government to control the radio spectrum. To prevent problems arising from new technologies or inappropriate upgrades, it is essential to guarantee backward compatibility [60].

One major technical issue with ITS deployment is the incompatibility of various vehicle-to-everything (V2X) protocols, including DSRC (IEEE 802.11p), LTE-V2X and the more recent C-V2X standards. Although these protocols operate on similar spectra (5.9 GHz band), they are not directly compatible at the communication level, which causes problems in fragmentation and integration. In addition, the infrastructure requirements differ: DSRC requires dedicated hardware exclusively for short-range communications, while C-V2X can use cellular networks in addition to roadside units [61].

Some cities and corridors have begun to deploy dual-mode roadside units that support both DSRC and C-V2X to address these issues. This allows for backward compatibility during the transition phase. In addition, newer 5G-based C-V2X equipment will fall back to LTE-V2X to enable communication with older vehicles. While hybrid approaches offer a temporary solution, continued standardization (e.g., IEEE 802.11bd, 5G NR V2X) and regulatory harmonization are essential for interoperability and effective ITS deployment in the long term [62].

5.2.2. Data Sharing and Cooperation Between Actors

The evaluation of the existing ITS Directive highlights persistent problems related to the availability and sharing of data that are necessary for the provision of reliable ITS services. When stakeholders do not work together or do not collaborate well, these problems are exacerbated [63]. This highlights the need for better compliance with current practices and rules.

The European Commission recognizes that ITS deployment is often limited to a narrow geographical scale, and that further measures are needed to improve interoperability and data sharing across the European Union [64].

5.2.3. Regulatory and Administrative Barriers

Businesses and service providers face restrictive regulations that differ greatly between Member States and hinder cross-border ITS operations. The use of these divergent regulatory strategies could lead to the unnecessary duplication of compliance checks; this can complicate the market entry of new technologies and innovations [65].

Despite the European Commission’s efforts to address these regulatory obstacles, many issues remain unresolved, in particular regarding the rapid availability of permits required for the deployment of new technologies [66].

To overcome these regulatory obstacles and accommodate emerging technologies, policymakers should consider several best practices. One approach is to adopt technology-neutral regulatory frameworks that neither impose nor favor specific technical solutions, providing flexibility to integrate innovations like blockchain and AI without constant legal overhauls [67].

An additional approach is the use of regulatory test scenarios, which provide a controlled environment for testing innovative ITS solutions under regulatory oversight. This reduces uncertainty for innovators and provides evidence-based information for future regulatory design [68]. To prevent regulatory fragmentation and enable seamless transnational ITS operations, it is equally important to pursue cross-border legal alignment, i.e., the harmonization of standards and recognition of regulations across jurisdictions. Finally, the incorporation of robust data and AI governance frameworks (e.g., clear guidelines on algorithmic safety, liability, privacy and ethics) is essential for managing the risks of AI-powered mobility and for strengthening public trust in ITS innovations [69]. Overall, these measures ensure that regulatory frameworks promote, rather than hinder, advances in Intelligent Transport Systems, while protecting the public interest.

5.2.4. Challenges in Scalability and ITS Deployment

Because there are many stakeholders involved, the large-scale deployment of ITS technologies presents a number of complicated issues. This often leads to fragmented initiatives that are difficult to transfer to other cities. Each plan is based on specific local needs, making it difficult to implement the widespread adoption required to have a transformative impact on urban sustainability and mobility [70].

5.2.5. Information Security and Privacy in ITSs

Ensuring the security of user information has become a priority in Europe, as Intelligent Transport Systems rely heavily on real-time data exchange and connectivity. The General Data Protection Regulation (GDPR) is essential for setting standards for data privacy in information and technology systems (ITSs). Projects such as DataVaults and CyberSec4Europe aim to create secure frameworks for managing mobility data. In addition, the European Commission supports initiatives focused on cybersecurity by design, ensuring that ITS platforms include encryption, authentication protocols and intrusion detection systems to prevent data breaches and malicious attacks [71].

5.2.6. Synergies with Other Sectors

In Europe, there is a continuous effort to promote cooperation between the transport and aerospace domains to improve timing and positioning services needed for ITS applications. Although the European Union Space Programme provides vital space-based information, the full potential of these collaborations has not yet been fully exploited [72]. To maximize the benefits of digitalization in the road sector and to facilitate the faster deployment of ITS services across Europe, it is essential to address issues related to interoperability, cooperation and data sharing [73].

5.3. Measuring the Success and Efficiency of ITSs in Europe

In Europe, the evaluation of ITSs is based on Key Performance Indicators (KPIs), which are used to assess the efficiency and success of the systems. These KPIs include a thorough analysis of the terminology, calculation methods and types of calculations used in each of the 28 EU countries.

Figure 8 presents important elements for measuring the success and effectiveness of ITS implementation. These include quantitative and qualitative KPIs; evaluation criteria such as benchmarking and compliance with standards; recommendations for improvements through training and improved data collection; and evaluation issues such as resource limitations and data accuracy.

A study led by DG MOVE, the European Commission’s Directorate-General for Mobility and Transport, found good practices and current applications of the KPIs in the European Union, involving stakeholders through interviews and workshops [74]. Specific ITS KPIs include

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Reducing travel times;

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Increasing road safety, including reducing the number of crashes and fatalities;

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Optimizing fuel consumption and reducing carbon emissions;

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Increasing the use of public transport and sustainable alternatives.

Evaluation criteria based on the SMART matrix (Specific, Measurable, Attainable, Relevant and Time-bound) are used to evaluate smart mobility strategies. In order to establish accountability in assessing the effects and success of ITS implementation, this evaluation framework emphasizes the importance of setting concrete and measurable objectives [75]. ITS evaluation includes the following indicators:

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Output indicators: Immediate data, such as the number of sensors installed or kilometers of smart infrastructure developed;

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Impact indicators: Measuring long-term effects, such as reducing pollution and increasing energy efficiency.

5.3.1. Challenges in Evaluation

While evaluation frameworks for ITSs and smart city initiatives exist, they often focus on technological, social and economic elements, neglecting environmental consequences. Understandings of the role of ITSs in global sustainability are limited by the lack of comprehensive evaluation models. In addition, issues of the interoperability of ITS services and difficulties in data sharing continue to constitute significant obstacles to effective evaluation [76]. Such challenges include

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The lack of standardization of indicators across Member States;

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The limited access to relevant data for evaluation;

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Difficulties in measuring the indirect impact of ITSs on health and the environment.

5.3.2. Recommendations for Improvement

The following measures are suggested to improve the efficiency of ITSs [77]:

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The mandatory collection and sharing of essential data to guarantee their quality and accessibility;

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Encouraging collaboration between stakeholders, such as local authorities, private enterprises and end-users;

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Strengthening support mechanisms, such as the INNOSUP program, which helps SMEs (Small and Medium-sized Enterprises) to develop innovations and helps to develop new technologies and transport solutions.

By funding projects that promote emerging technologies in transport and mobility, the INNOSUP program, part of Horizon 2020, plays a key role in promoting innovation. The program accelerates the introduction of new ITS solutions to the European market by supporting SMEs [78].

To further develop ITSs and achieve the goals of sustainability and enhanced urban mobility, it is essential to measure their efficiency and success in Europe. KPIs, together with strict evaluation frameworks and cooperation between stakeholders, guarantee coherent and efficient ITS deployment at the EU level. However, to solve the current problems, an integrated approach is needed that includes data standardization, interoperability and open data sharing.

5.4. Future Trends in ITSs in Europe

Advances in digital technologies and innovative practices have led to a significant transformation of the ITS industry in Europe. The European Commission has highlighted the importance of the Strategic Technology Platform in Europe to increase manufacturing capabilities in areas such as microelectronics, artificial intelligence and cybersecurity. Ensuring the necessary technological infrastructure is essential to help the adoption of ITSs [79]. According to Figure 9, future trends in ITSs focus on four main pillars: sustainable mobility, artificial intelligence and automation, digitalization, and policy frameworks. All these trends lead to a more efficient, safe and environmentally sound future of transport.

A major trend that will change mobility in Europe will be the integration of automation and artificial intelligence into transport systems. Increasing safety, optimizing routes and optimizing traffic management are all possible with the help of emerging automation technologies. AI-based solutions will be essential for the development of the industry in terms of predictive maintenance, facilitating real-time decisions and analyzing big data volumes [53].

According to the eGovernment Benchmark, the ongoing digital transformation of public services demonstrates the commitment of European countries to modernizing transport infrastructure. The 2021 and 2022 eGovernment Benchmark reports indicate significant progress in the digitalization of government services, directly influencing the implementation of ITS technologies. This transformation is crucial for creating seamless interfaces between users and transport systems [80].

The current legislative and regulatory framework will have a significant impact on future trends in ITSs. The aim of the revision of the ITS Directive is to ensure the efficient integration of emerging technologies into existing systems. The proposed measures focus on accelerating the implementation of innovations without bureaucratic obstacles and improving collaboration between stakeholders. These actions are essential for Europe to adapt to ever-changing technological evolutions while addressing environmental issues and traffic congestion [81].

Sustainable mobility will remain a major priority in the development of ITSs. Transport solutions that encourage environmentally friendly practices, such as cycling, walking and public transport, will be integrated into future climate goals. This emphasis reflects both regulatory pressures and the public desire for more sustainable urban mobility options [82].

The integration of advanced technologies, innovative policies and an increased focus on sustainability will shape the future of ITSs as Europe continues to invest in Intelligent Transport Systems. Efficient and environmentally friendly urban mobility, adapted to the needs of the 21st century, will require collaboration between authorities, the technology industry and local communities.

6. Conclusions and Discussions

In Europe, the deployment and development of Intelligent Transport Systems (ITSs) are continuous processes of adaptation to the emerging challenges of urban and regional mobility. Europe has demonstrated a remarkable capacity for innovation and adaptation since the adoption of Directive 2010/40/EU, which created a coherent framework for the integration of ITSs by all Member States. This has continued with the deployment of emerging technologies such as autonomous vehicles, the Internet of Things (IoT) and artificial intelligence (AI).

These changes have been driven by the desire to improve the safety, efficiency and sustainability of transport. Projects such as Euralille 3000 and initiatives in cities such as Berlin, Kaunas, Riga, Tartu and Cluj-Napoca demonstrate how ITSs can change urban infrastructure, reducing emissions, optimizing road traffic flows and improving the quality of life in cities. The benefits of ITSs are multiple, and these benefits cover key areas:

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A positive impact on the environment by reducing CO₂ emissions and air pollution;

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Improving road safety with technologies such as eCall and C-ITSs, which reduce the frequency and severity of road traffic crashes;

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Economic efficiency, with ITSs contributing to reducing travel times and optimizing fuel consumption;

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Improving public health by reducing exposure to traffic-related pollution and promoting active mobility.

In Europe, despite these advantages, there are a number of challenges. The adoption of ITSs is not uniform due to technical interoperability issues, insufficient data sharing and regulatory issues. In addition, to assess the impact of ITSs on society and the environment, stronger assessment frameworks and standardized indicators are needed.

The integration of emerging technologies such as 5G, blockchain and vehicle automation will have a significant impact on the future of ITSs in Europe. Encouraging innovation and accelerating ITS deployment will be possible through EU policies and funding initiatives such as Horizon 2020 and INNOSUP. In addition, the strategic directions of ITSs in the coming decades will be driven by an increased focus on sustainable mobility and green solutions.

The future development of ITSs may face significant political and financial obstacles, in addition to the technical and legal challenges mentioned above. Smart mobility strategies may delay large-scale deployment, especially in resource-constrained Member States, if there is no sustained political will or prioritization. Furthermore, to ensure equity and continuity in ITS deployment, access to stable funding and long-term political support is necessary. To overcome these systemic constraints and accelerate ITS deployment in all regions, it will be necessary to strengthen EU-level instruments, such as Horizon Europe, as well as to promote effective public–private partnerships.

Ultimately, the future of urban and regional transport depends on Intelligent Transport Systems. Europe has the chance to become a world leader in this field if it supports technological progress, sustainability and social inclusion in transport.