International Perspectives on Emergency Vehicle Warning Systems: Contrasts and Comparisons

Emergency vehicle warning systems are designed to alert other road users of the presence and approach of emergency vehicles (EVs) on call, such as ambulances, fire trucks, and police cars. These systems typically consist of sirens and emergency lights, which are intended to demand the right of way and to facilitate safe and efficient passage for the EVs. However, these systems have some limitations, such as limited reach and detectability, especially in urban environments with high traffic density, noise, and visual clutter. Moreover, different countries may have different regulations, standards, and practices regarding the use and design of emergency vehicle warning systems, which may affect their effectiveness and compatibility.

In this post, we will review some of the international perspectives on emergency vehicle warning systems, and compare and contrast their features, benefits, and challenges. We will also discuss some of the emerging technologies and innovations that aim to enhance the performance and safety of emergency vehicle warning systems, such as vehicle-to-everything (V2X) communication, broadcast hyper local messages, and privacy ensuring mechanisms.

One of the main factors that influence the design and use of emergency vehicle warning systems is the legal framework that governs the rights and obligations of EVs and other road users. For example, in some countries, such as the United States, Canada, and Australia, EVs are allowed to violate certain traffic rules, such as speed limits, red lights, and stop signs, when responding to emergencies, as long as they use their sirens and lights and exercise due care. In other countries, such as Sweden, Germany, and Japan, EVs are not exempt from traffic rules, but have priority over other vehicles when using their sirens and lights. Other road users are required to give way to EVs by moving to the side of the road or stopping if necessary. However, there may be variations in how these rules are enforced and complied with in different regions or situations.

Another factor that affects the design and use of emergency vehicle warning systems is the physical and cultural environment that characterizes different countries or regions. For example, in some countries with large land areas and low population density, such as Australia and Canada, EVs may have to travel long distances to reach their destinations, which may require louder sirens or more visible lights. In contrast, in some countries with high population density and urbanization, such as Japan and South Korea, EVs may face more challenges in navigating through congested traffic and complex road networks, which may require more sophisticated warning systems or additional information for other road users. Furthermore, different cultures may have different preferences or expectations regarding the sound and appearance of emergency vehicle warning systems. For example, some cultures may prefer high-pitched sirens or flashing lights, while others may prefer low-pitched sirens or steady lights.

One of the emerging trends in emergency vehicle warning systems is the use of V2X communication technology, which enables EVs to communicate with other vehicles, infrastructure, devices, or networks in their surroundings. V2X communication can provide more reliable and timely information about the location, direction, speed, type, and level of emergency of EVs to other road users, as well as to traffic signals or controllers. This can help other road users to detect EVs earlier and more accurately, and to give way more appropriately. It can also help EVs to optimize their routes and to coordinate their movements with other EVs or traffic agents. For example, a V2X-based highly reliable warning system for EVs has been proposed by Selvaraj et al. (2023), which uses a jitter-to-highly reliable (J2H) approach of customizing the traffic signals and an alert passer mechanism to alert other vehicles based on the GPS position of the EV .

Another emerging trend in emergency vehicle warning systems is the use of broadcast hyper local messages to alert other road users of the approach of EVs via radio or other media channels. These messages can provide additional information or instructions for other road users on how to give way properly to EVs. They can also complement or substitute the sirens or lights when they are not effective or available. For example,
a study by Lidestam et al. (2020) tested the effect of an in-car warning message via RDS radio on car drivers' propensity to give way to an approaching ambulance . The results showed that the message made drivers give way earlier and learned to give way earlier even without a message. The study also suggested that the message was necessary for making inexperienced drivers give way to an approaching EV.

A third emerging trend in emergency vehicle warning systems is the use of privacy ensuring mechanisms to protect the identity and confidentiality of EVs and their passengers or clients. These mechanisms can prevent unauthorized access or misuse of the information transmitted or received by EVs or other road users via V2X communication or broadcast messages. They can also respect the preferences or rights of EVs or other road users regarding the disclosure or sharing of their information. For example, a feasibility study of privacy ensuring emergency vehicle warning system using blockchain technology has been conducted by Kaur et al. (2020), which uses a smart contract to verify the authenticity and validity of the EV and to encrypt and decrypt the information exchanged between the EV and other vehicles .

In conclusion, emergency vehicle warning systems are important for ensuring the safety and efficiency of emergency driving and response. However, different countries or regions may have different perspectives and practices regarding the design and use of these systems, which may pose some challenges or opportunities for their improvement and harmonization. Some of the emerging technologies and innovations that aim to enhance the performance and safety of emergency vehicle warning systems include V2X communication, broadcast hyper local messages, and privacy ensuring mechanisms. These technologies and innovations may offer some benefits, such as increased awareness, reliability, timeliness, and security of information, but may also entail some risks, such as increased complexity, cost, or vulnerability of the systems.