This study investigates drivers’ eye gaze behavior in response to Emergency Vehicle Approaching (EVA) warnings. EVA warnings, delivered through in-car alerts, provide advance notice of approaching EVs, enabling drivers to move over in time. Previous research indicates that EVA warnings influence driver behavior positively, promoting safer interactions. This study expands further by exploring the role of system introduction to make drivers benefit from EVA warnings. A simulator experiment with 73 participants was conducted. Before driving, half of the participants were introduced to the EVA system. The participants were driving on a highway and were overtaken by EVs twice during a 20-minute drive. During the drive, half of participants received EVA warnings. Gaze distribution was analyzed in three areas of interest (Forward, Mirrors, Dashboards). Analysis of driving simulator data did not reveal any differences in driving behaviors. However, the analysis of drivers’ gaze distribution suggests that EVA warnings contribute to increased mirror usage, indicating early scanning for approaching EVs. Furthermore, drivers who were introduced to the EVA system before driving but never received an EVA warning in the simulator looked through the front windshield less than drivers who were introduced and received an EVA warning. This study contributes to understanding the driver gaze behavior when receiving an in-car warning for emergency vehicles and supports previous findings regarding EVA warnings positive impact of driver behavior.

Emergency vehicle lightings (EVL) mitigate the risk of collision and make drivers move over. The present paper explored how new alternative EVL designs can improve driver behavior in different emergency vehicle interaction scenarios. From workshops with 14 emergency responders, three scenarios (Emergency driving, Police pull-over, Emergency vehicle alongside the road) and 19 EVL blink patterns were chosen. These alternative EVLs were presented in an online survey with 2627 Swedish respondents. Alternative EVL affected reported driving behavior. Drivers reported being most certain of what is expected from them in the emergency-driving scenario. It is important to ensure that the EVL is easy to interpret in more unfamiliar emergency-vehicle interactions such as police pull-over. Only a third of drivers had seen the pull-over EVL currently used in Sweden. The current pull-over EVL in combination with a stop sign increased the chance of drivers reporting that they would pull over.

Driving an emergency vehicle can be difficult. The driver of the emergency vehicle must navigate, communicate with emergency services, often drive at high speeds, and take surrounding traffic into account. Civilian drivers are required by law to give way to emergency vehicles with lights and sirens activated. Despite this, they sometimes fail to move over. One reason is not noticing the emergency vehicle in time.   

This dissertation aims to understand how technology can support civilian drivers in their interactions with emergency vehicles. One form of technology used to make drivers move over is emergency vehicle lighting. The results of this dissertation show that alternative designs of emergency vehicle lighting can affect driver behavior and that the current designs are not always suited to promote the most desirable driver behavior.   

Another technological approach to supporting drivers in their interactions with emergency vehicles is the use of Cooperative Intelligent Transport Systems (C-ITS). One C-ITS service is the Emergency Vehicle Approaching (EVA) warning. An EVA warning is an early in-car warning sent out to the driver before being overtaken by an emergency vehicle, providing more time to move over. Three driving simulator studies with EVA warnings were conducted in this dissertation. The results indicate that EVA warnings make drivers move over more quickly and thereby decrease delay time for emergency vehicles. Furthermore, there is a learning effect when receiving multiple EVA warnings, implying that drivers move over more quickly once they are familiar with the system. One of the simulator studies used eye tracking and showed that EVA warnings make drivers scan mirrors earlier, compared to when not receiving an EVA warning.   

An EVA warning is distributed based on the most probable path of the emergency vehicle. If the driver of the emergency vehicle decides on another route, there is a risk of false EVA warnings. Therefore, this dissertation explored how false alarms, and false expectations of EVA warnings, affect drivers. Receiving false alarms makes drivers move over more slowly in future interactions and negatively affects attitudes toward the EVA system. Furthermore, wrongly expecting an EVA warning makes drivers less attentive to the road ahead.    

In conclusion, both emergency vehicle lighting and EVA warnings can support civilian drivers in their interactions with emergency vehicles. It can decrease the risks of both collisions and delays. However, to implement a large-scale deployment of C-ITS, Sweden needs digital infrastructure to support secure data exchange  

Att framföra ett utryckningsfordon är utmanande. Utryckningsföraren förväntas navigera, kommunicera med larmcentralen, framföra utryckningsfordonet i inte sällan höga hastigheter och samtidigt ta hänsyn till omgivande trafik. Bilister är enligt lag tvungna att lämna fri väg för utryckningsfordon med blåljus och sirener. Trots det misslyckas ibland förare med att lämna fri väg. En anledning är att de inte hinner uppfatta utryckningsfordonet i tid.

Syftet med denna avhandling är att förstå hur teknik kan stödja förare vid interaktioner med utryckningsfordon. En form av teknik som används för att få förare att lämna fri väg är blåljus. Resultaten av denna avhandling visar att alternativa designlösningar för blåljus kan påverka förarnas beteende och att de nu-varande utformningarna inte alltid är optimala för att främja det mest önskvärda förarbeteendet.   

En annan metod för att stötta förare i deras interaktion med utryckningsfordon är uppkopplad fordonsteknik, så kallat Cooperative Intelligent Transport Systems (C-ITS). En typ av C-ITS-tjänst är Emergency Vehicle Approaching (EVA)-varningar. En EVA-varning är en tidig varning som skickas ut till bilisten innan utryckningsfordonet kör ikapp, vilket ger föraren mer tid att lämna fri väg. Tre förarsimulatorstudier med EVA-varningar genomfördes inom ramen för avhandlingen. Resultaten visar på att EVA-varningar kan få förare att lämna fri väg snabbare och därmed minska förseningar för utryckningsfordon. Dessutom finns det en inlärningseffekt med EVA varningar som innebär att förare lämnar fri väg snabbare när de är bekanta med EVA systemet. I en av simulatorstudierna användes ögonrörelsemätning som visade att EVA-varningar får förare att skanna av speglarna i bilen tidigare, jämfört med när de inte får någon EVA-varning.   

En EVA-varning distribueras baserat på den mest sannolika vägen för utryckningsfordonet. Om föraren av utryckningsfordonet väljer en annan väg finns det risk för falska EVA-varningar. I den här avhandlingen undersöktes därför hur falska larm och en falsk förväntan om EVA-varningar påverkar förare. Att ta emot falska larm påverkade förarnas framtida interaktioner och inställning till EVA-systemet. Dessutom gjorde en felaktig förväntan på en EVA-varning till att förarna var mindre uppmärksamma på vägen framför dem.   

Sammanfattningsvis kan både blåljus och EVA-varningar stödja civila förare i interaktionen med utryckningsfordon. Varningssystemen kan minska riskerna för både kollisioner och förseningar. För att genomföra en storskalig utbyggnad av C-ITS behöver Sverige dock en digital infrastruktur för att stödja säkert datautbyte. 

The interaction between emergency vehicle drivers and surrounding road users is associated with risks. This study explored the application of geofencing to improve interactions between drivers and emergency vehicles to reduce the risk of collisions in high-risk scenarios. Two high-risk scenarios, an off-ramp collision, and an intersection scenario, were used in two driving simulator experiments with 64 participants in total. Half of the drivers received a geofence-based warning about the upcoming traffic situation. The results indicate that geofencing, when applied to provide warnings in specific locations, improves driver behavior. In the off-ramp experiment, all drivers who received a warning avoided the off-ramp and thereby avoided the collision site, whereas all other drivers took the off-ramp. In the intersection experiment, the warning led to earlier deceleration, allowing the emergency vehicle to pass safely and with minimal delay; whereas nearly half of those who did not get a warning failed to yield to the emergency vehicle. The drivers acted based on the warning they received, even when they had not yet seen the emergency vehicle. The findings suggest that geofencing can improve driver behavior by detecting emergency vehicles early and reliably, thereby improving traffic safety and minimizing delay for emergency vehicles on call.

Emergency driving is a demanding task. The ITS service Emergency Vehicle Approaching provides drivers with an in-car warning that an emergency vehicle is approaching. To ensure that the warning is efficient and reliable it must have a suitable timing. The EVA warning must be presented early enough to allow the driver to make a safe move-over maneuver. However, the distribution of EVA warnings is based on the most probable path of the emergency vehicle. If an EVA warning is distributed too early, it increases the risk of false alarms. In addition, if a warning is given too early the driver might deem it as irrelevant.

Previous studies have distributed EVA warnings based on the distance between the emergency vehicle and surrounding cars. However, if the speed of the vehicle is not accounted for there is a risk of insufficient time for the driver to prepare for the emergency vehicle interaction. To explore suitable EVA timing, post-survey data from five driving simulator studies where drivers were exposed to EVA warnings were analyzed. The results suggest that 15–20 seconds could be an appropriate EVA timing. However, the required time for a move-over maneuver depends on the complexity of the current traffic situation.