Nonparametric Comparative Analysis of Driver Behaviors in Signalized and Non-Signalized Roundabouts: A Study on Road Safety in Qatar

Abstract

This study investigated and compared driver behaviors at signalized and non-signalized roundabouts in Qatar, focusing on turn signal usage, lane change behavior, and correct lane usage. The primary objectives were to determine the frequency of turn signal usage, assess correct lane usage, analyze lane change behavior, and compare these behaviors between the two types of roundabouts. Data were collected through a field study at selected roundabouts, where driver behaviors were observed and analyzed. The results revealed significant differences between signalized and non-signalized roundabouts. Turn signal compliance was higher in signalized roundabouts (up to 45%) compared to non-signalized roundabouts (20%). The rate of lane change in signalized roundabouts was observed to be 31%, whereas it was 14% in non-signalized roundabouts, and correct lane usage compliance was higher in signalized roundabouts (60%) compared to non-signalized roundabouts (35%). These findings suggest that traffic signals contribute to safer and more predictable driver behavior, although congestion and long waiting times in signalized roundabouts present challenges. The study recommends improving signage visibility, optimizing signal timings, enhancing road markings, and enforcing traffic regulations to address these issues. The findings can inform traffic engineers and policymakers in enhancing the safety and efficiency of roundabouts.

1. Introduction

Driving behavior plays a critical role in ensuring road safety and efficient traffic flow. As a fundamental aspect of a driver’s behavior, understanding how drivers navigate roundabouts is of paramount importance. Roundabouts provide a safe and efficient alternative to traditional intersections, reducing congestion and improving traffic flow [1]. However, the effectiveness of roundabouts depends heavily on driver compliance with traffic rules and regulations, particularly regarding turn signal usage, lane change behavior, and correct lane usage. This study aims to investigate and compare these key driver behaviors in signalized and non-signalized roundabouts in Qatar.

The need for this study arises from the lack of inclusive research specifically focusing on driver behavior within signalized and non-signalized roundabouts in Qatar. Enhancing our understanding of how drivers interact with roundabouts will not only contribute to our knowledge of their behavior but also provide understanding for traffic engineers and policymakers. While studies have addressed driver behavior in roundabouts, the unique traffic conditions, cultural factors, and rapid urban development in Qatar present a distinct context that warrants targeted investigation [2]. Previous research has demonstrated various benefits and criticalities associated with different types of road intersections. For instance, studies have shown that signalized roundabouts can improve traffic management by providing clear indications to drivers, thus reducing confusion and enhancing safety in high-demand situations [3]. However, these benefits can be offset by increased delays and the complexity of driver decision-making [4]. On the other hand, non-signalized roundabouts, while promoting smoother traffic flow, can pose significant challenges to driver comprehension, necessitating additional traffic calming measures to ensure safety [5]. These findings underscore the importance of context-specific studies, such as the one presented here, to understand how these global insights apply within the unique traffic environment of Qatar. By examining turn signal usage, lane change behavior, and correct lane usage, areas where driver compliance may be lacking can be identified, leading to potential safety hazards and traffic disruptions. This study will contribute to the existing body of knowledge on driver behavior in roundabouts, furthering our understanding of the influence of different factors on driver decision-making.

Although specific statistical data on car accidents in Qatar in relation to roundabouts are currently unavailable, information from the Gulf Cooperation Council (GCC) region can provide some insights. In the Emirate of Abu Dhabi, an analysis was conducted on 2008 intersection crashes that occurred between 2012 and 2017. The findings revealed that out of these incidents, 1214 crashes (60.45% of the total) transpired at signalized intersections, while 794 crashes (39.55% of the total) occurred at roundabouts [6]. Notably, fatalities were reported in 7% of the roundabout crashes, whereas 3.7% of the crashes at signalized intersections resulted in fatalities.

It is important to note that these findings from Abu Dhabi contrast with several international studies, which typically report lower fatality rates at roundabouts compared to signalized intersections due to reduced conflict points and lower vehicle speeds [7,8]. The higher fatality rate at roundabouts, in this case, may be influenced by local factors such as driver behavior, roundabout design, or enforcement practices. Further comparison with global studies and local investigations is recommended to understand the factors contributing to this deviation from common trends.

Previous research has shown that driver behavior at roundabouts is significantly influenced by psychotechnical parameters such as critical gaps and follow-up times [9]. Critical gaps, the minimum acceptable gap between vehicles for safe entry, and follow-up times, the interval between successive vehicles entering the roundabout, are crucial in modeling driver interactions [10]. Additionally, user perceptions of safety at roundabouts, which can vary significantly, also play a vital role in driver behavior [11]. These factors are essential for an inclusive understanding of driver behavior and have been explored extensively in the literature.

The primary objective of this study was to conduct a comparison of driver behaviors in signalized and non-signalized roundabouts in Qatar. Specific objectives included determining the frequency of turn signal usage, evaluating the correct lane usage, analyzing lane change behavior, and comparing driver behavior between the two types of roundabouts.

Qatar’s Traffic Environment and Its Influence on Roundabout Behavior

Qatar’s traffic environment is characterized by high vehicle ownership, a multicultural driving population, and rapid infrastructure development. These factors significantly influence driver behavior at roundabouts, affecting lane discipline, signal compliance, and overall traffic flow.

The diverse driving norms in Qatar stem from its large expatriate population, with drivers bringing varied habits and expectations regarding roundabout navigation. This diversity can lead to inconsistencies in lane discipline and signal usage, as some drivers adhere strictly to traffic rules while others may have different interpretations. A study comparing driving behaviors among different ethnic groups in Qatar found significant variations in violations, errors, and lapses, highlighting the impact of cultural differences on driving practices [12].

High dependence on private vehicles contributes to congestion, especially at major urban roundabouts. During peak hours, signalized roundabouts often experience long queues, leading to driver frustration and impatience. This situation prompts last-minute lane changes as drivers attempt to reduce waiting times. Research on driver behavior at minor-street stop-controlled intersections in Qatar indicates that aggressive driving and risky behaviors are prevalent, with critical gap acceptance values lower than those in other countries [13].

Despite strict traffic regulations, enforcing lane discipline within roundabouts remains challenging. Qatar employs automated systems to monitor speeding and red-light violations; however, improper lane changes are not consistently addressed. The presence of traffic cameras has improved compliance with signal rules but has not significantly reduced erratic lane-changing behaviors. A study utilizing the Driver Behavior Questionnaire in Qatar and Turkey identified a correlation between aggressive driving behaviors and accident involvement, underscoring the need for targeted enforcement strategies [14].

Rapid infrastructure development in Qatar has led to modern road networks and advanced roundabout designs. However, some older roundabouts lack optimal lane guidance and clear signage, contributing to driver uncertainty and sudden maneuvers. Inconsistent road designs and frequent construction projects further exacerbate this issue, making it difficult for drivers to anticipate correct lane choices. Guidelines on driving in Qatar emphasize that while lane discipline is encouraged, actual driving practices may vary, leading to potential confusion at roundabouts [15].

Cultural factors and driving attitudes also play a role in roundabout navigation. Some drivers prioritize speed and efficiency over strict adherence to lane rules, resulting in aggressive lane changes and reduced compliance with traffic regulations. Others, unfamiliar with local roundabout designs, may hesitate or make last-minute decisions, slowing traffic flow and increasing the risk of conflicts. Understanding these cultural influences is essential for developing effective interventions to improve roundabout safety and efficiency.

In summary, Qatar’s unique traffic environment—shaped by a multicultural driver base, high vehicle usage, evolving infrastructure, and distinct cultural attitudes—profoundly impacts driver behavior at roundabouts. Addressing issues such as improper lane changes and signal compliance requires a multifaceted approach, including infrastructure enhancements, stringent enforcement, and culturally tailored driver education programs.

2. Literature Review

Junction control is a crucial aspect of roundabout design and operation, focusing on managing traffic movements within roundabouts to ensure efficient and safe traffic flow. Two main approaches are employed: signalized roundabouts and non-signalized roundabouts. A signalized roundabout is a circular intersection equipped with traffic signals at one or more entry points to regulate traffic flow. These signals regulate both the entry and internal circulation of vehicles within the roundabout, facilitating smoother traffic flow and reducing potential conflicts [16,17]. These roundabouts offer clear indications to drivers and allow for better management in high-demand situations [18]. However, signalized roundabouts may introduce delays and increase the complexity of driver decision-making [19]. On the other hand, non-signalized roundabouts lack traffic signals and rely on yield signs to control traffic. These roundabouts utilize yield signs, as well as other signage and pavement markings, to guide drivers through the intersection. Non-signalized roundabouts require drivers to yield to vehicles already in the roundabout, resulting in a smoother and more efficient traffic flow [20]. However, non-signalized roundabouts may pose challenges for driver comprehension and may require additional traffic calming measures to ensure safety.

Driver behavior represents a significant factor influencing road safety and traffic flow at roundabouts. Numerous studies have explored driver behavior at roundabouts, investigating factors such as lane changing, correct lane usage, and turn signal usage [21,22,23,24]. These studies have discovered that drivers often engage in frequent lane changes, leading to an increase in conflicts and accidents. Driver behavior is influenced not only by internal factors but also by external factors present in the driving environment. External factors can include road infrastructure, traffic congestion, weather conditions, and the behavior of other road users. Studies have examined how these external factors affect driver decision-making and behavior [22]. For example, research has shown that drivers tend to adapt their behavior in response to varying traffic conditions [23]. Factors such as the presence of pedestrians, bicyclists, and other vehicles can influence driver behavior and the likelihood of certain maneuvers. Understanding how external factors shape driver decision-making can inform the design of safer road environments and improve overall traffic management.

The distinction between signalized and non-signalized roundabouts is essential because driver behavior can vary depending on the type of roundabout. A study compared driver behavior in signalized and non-signalized roundabouts and found that drivers exhibited more cautious behavior in signalized roundabouts [24]. This included reduced speeds and increased turn signal usage, potentially enhancing safety within these roundabouts. However, the study also highlighted potential issues related to driver confusion and increased rear-end collision risk at signalized roundabouts. These findings suggest the need for careful consideration when implementing traffic signals in roundabouts to mitigate potential drawbacks.

Lane change behavior within roundabouts refers to the movement of vehicles from one lane to another while circulating inside the roundabout. Understanding driver lane change behavior is crucial for optimizing traffic flow and reducing the risk of accidents. Previous studies have explored factors influencing lane change behavior within roundabouts, including traffic volume, roundabout geometry, and driver characteristics [25,26,27]. Research has shown that drivers tend to change lanes more frequently in larger roundabouts with multiple entry lanes [26]. The presence of traffic signals also influences lane change behavior, with drivers exhibiting a higher incidence of lane changes in signalized roundabouts compared to non-signalized ones. These findings suggest that both roundabout design and traffic control measures play a significant role in shaping lane change behavior. Another study investigated driver lane change behavior in roundabouts and found that driver demographics, such as age and gender, influenced the likelihood of lane changes [27]. Younger drivers and male drivers were more likely to change lanes compared to older drivers and female drivers. The study also highlighted the impact of traffic flow and lane configuration on lane change behavior. These findings provide comprehension of the factors influencing lane change behavior within roundabouts and can inform traffic engineering practices to improve safety and efficiency.

Correct lane usage is vital for ensuring smooth traffic flow and minimizing conflicts within roundabouts. Drivers must select the lane before entering the roundabout and maintain their lane position until exiting. Studies have investigated factors influencing correct lane usage, highlighting the importance of signage, markings, and lane guidance [28,29]. Research demonstrated that clear and consistent roundabout signage significantly influenced driver compliance with proper lane usage [29]. Similarly, a study revealed that lane arrows and pavement markings positively affected driver adherence to correct lane usage [30]. Furthermore, incorrect lane usage appears to be more prevalent in non-signalized roundabouts compared to signalized roundabouts.

Turn signal usage is also crucial within roundabouts, as drivers should indicate their intention to enter or exit the roundabout to other drivers. Nevertheless, research has revealed that many drivers fail to signal their intentions when entering or exiting roundabouts [31]. A study demonstrated that less than half of the drivers signaled their intent when exiting the roundabout, and only a small percentage signaled when entering the roundabout [32]. Drivers at non-signalized roundabouts display a lower likelihood of using turn signals compared to drivers at signalized roundabouts [33]. In a recent study conducted in 2022, the rate of turn signal usage at two-lane roundabouts in Doha was assessed [34]. The study reported a remarkably low rate of turn signal usage, ranging from 18% to 24%, at the roundabouts under investigation. The data collection method employed in this study was reasonable and proved suitable for this research as well, hence its adoption. Conversely, the absence of traffic signal usage can cause confusion and misinterpretation of driver intentions, potentially leading to accidents [35]. The presence of traffic signals is another crucial factor influencing a driver’s behavior at roundabouts. Studies suggest that the presence of traffic signals can affect driver behavior at roundabouts, particularly concerning turn signal usage [36]. Drivers are more likely to use turn signals at signalized roundabouts compared to non-signalized roundabouts [37].

Therefore, this existing body of literature highlights the significant impact of junction control on driver behavior within roundabouts. Studies have consistently shown that signalized roundabouts, equipped with traffic signals, tend to regulate traffic flow more predictably and improve turn signal compliance. Conversely, non-signalized roundabouts, relying on yield signs and road markings, often present challenges in driver comprehension and behavior consistency.

3. Research Model and Methodology

3.1. Research Model

This research aims to investigate the relationship between the independent variable and the dependent variables that are summarized in

Table 1. The following table defines the variables for this research.

Independent Variable	Dependent Variables
Junction Control (Signalized and Non-Signalized)	Lane Change
	Correct Lane Usage (Entering/Exiting)
	Turn Signal Usage (Entering/Exiting)

and serve as key indicators for understanding driver behavior within roundabouts. By exploring these variables, the study seeks to gain a vision into the impact of junction control on driver actions and ultimately contributes to enhancing traffic flow efficiency and safety in roundabouts. The case study choice in this research paper is crucial as it focuses on investigating driver behaviors in signalized and non-signalized roundabouts in Qatar. This selection allows for a detailed examination of how drivers interact with roundabouts in a specific context characterized by unique traffic conditions, cultural factors, and rapid urban development. The methodological model employed in this study, including the use of nonparametric statistical methods, can be replicated in other regions with similar traffic conditions to generate comparable insights and recommendations.

Lane change refers to the action of vehicles changing lanes or switching from one lane to another while navigating inside a roundabout, which is illustrated in Figure 1. It measures the frequency and occurrence of lane changes made by drivers as they move through the circular intersection. This variable provides insight into driver behavior and decision-making during roundabout traversal. Lane changes can help drivers select the most suitable lane for their desired exit or accommodate varying traffic conditions. However, excessive or improper lane changes can disrupt the flow of traffic and increase the risk of accidents.

Correct lane usage refers to the extent to which drivers adhere to the designated lanes while navigating a roundabout, which is demonstrated in Figure 2. It assesses whether drivers choose and stay in the appropriate lane as they approach, circulate within, and exit the roundabout. Correct lane usage is an important measure of driver compliance with roundabout rules and contributes to the safe and efficient operation of the intersection. The concept of correct lane usage is based on the prescribed lane assignments in a roundabout, which are typically marked with pavement markings, signs, or other lane indicators. Each lane within the roundabout is designated for a specific exit or a specific direction of travel. Drivers should enter the roundabout using the appropriate entry lane and then choose and maintain the correct lane that aligns with their intended destination or travel path. Generally, the right lane is typically used for vehicles intending to take the first exit or continue straight, the middle lane is often for vehicles going straight or taking the second exit, and the left lane is used for vehicles preparing to take the second exit or to make a U-turn. Upon reaching the roundabout, the driver must yield to circulating traffic and use turn signals if a lane change is necessary before entry. Once inside, the driver should maintain their designated lane without unnecessary lane changes to avoid conflicts with other vehicles. When preparing to exit, the driver must signal in advance and ensure they are in the correct lane. Typically, vehicles in the right lane can exit directly, while those in the left lane must merge right before exiting safely.

The turn signal usage variable indicates the use of turn signals by drivers while maneuvering through a roundabout, which is illustrated in Figure 3. It measures the frequency and consistency with which drivers indicate their intention to change lanes or exit the roundabout by activating their vehicle’s turn signals. Turn signal usage is an important aspect of driver communication and contributes to the safe and predictable movement of vehicles within the roundabout. Activating the turn signal allows other drivers to anticipate and adjust their driving behavior accordingly, reducing the likelihood of collisions or conflicts. Proper use of turn signals promotes smooth traffic flow and enhances overall safety within the roundabout.

The hypotheses of this study aim to examine the relationship between different variables related to roundabouts. Specifically, the study focuses on the variables of lane change, correct lane usage, and turn signal usage, comparing the outcomes between signalized and non-signalized roundabouts. The hypotheses for each variable are as follows:

• Lane Change Hypotheses:
  • H₀: There is no significant difference in lane change behavior between signalized and non-signalized roundabouts;
  • H₁: There is a significant difference in lane change behavior between signalized and non-signalized roundabouts.
• Correct Lane Usage Hypotheses:
  • H₀: There is no significant difference in correct lane usage between signalized and non-signalized roundabouts;
  • H₁: There is a significant difference in correct lane usage between signalized and non-signalized roundabouts.
• Turn Signal Usage Hypotheses:
  • H₀: There is no significant difference in turn signal usage between signalized and non-signalized roundabouts;
  • H₁: There is a significant difference in turn signal usage between signalized and non-signalized roundabouts.

These hypotheses are formulated to investigate whether there are notable disparities in the behavior of drivers at signalized and non-signalized roundabouts regarding lane change, correct lane usage, and turn signal usage. By analyzing and comparing the data, the study aims to determine if these variables exhibit significant differences, providing an understanding of driver behavior in the context of roundabouts.

3.2. Methodology

In this study, a non-participant observational approach was employed to examine driver behavior at roundabouts. The researchers conducted passive observation, meaning they did not interact with drivers but instead recorded their natural driving behaviors. This method ensured that the collected data remained unbiased and reflective of real-world conditions. Additionally, the observations were unobtrusive, as drivers were unaware that they were being monitored, preventing any alteration in their driving patterns due to awareness of the study. Data collection took place in an actual driving environment rather than a controlled or simulated setting, providing insights into real traffic conditions and driver responses.

A field study was undertaken by a team of three researchers to gather data on driver behavior within roundabouts. Two roundabouts were carefully selected, one with traffic signals (signalized) and the other without (non-signalized). The primary objective of the study was to collect information regarding three key aspects: lane change behavior, correct lane usage, and turn signal usage exhibited by drivers navigating the roundabouts. The traffic volume was recorded over two days, with approximately three hours of observation per day at each roundabout. The data collectors visited the chosen roundabouts and embarked on the task of identifying and recording the aforementioned variables of interest. A checklist was provided to the data collectors to ensure accurate data collection. Positioned at a safe location near the roundabout, the data collectors attentively observed the behavior of drivers and documented their actions related to lane changes, correct lane usage, and turn signal activation. A total of 100 vehicles at each roundabout were observed, and their behavior was meticulously recorded by the data collectors. This sample size of 200 vehicles aimed to provide a representative snapshot of driver behavior within the selected roundabouts.

Once the data collection phase was complete, the gathered information underwent analysis using the statistical software Minitab 18. This analysis was conducted to discern the frequency and patterns associated with the variables of interest. The statistical analysis facilitated an examination of the gathered data, allowing for an understanding of the prevalence and tendencies of lane changes, correct lane usage, and turn signal activation among drivers in both signalized and non-signalized roundabouts. By employing the Minitab software, the study aimed to identify any noteworthy trends or differences in driver behavior between the two types of roundabouts. The utilization of a team of data collectors, meticulous observation protocols, and robust statistical analysis ensures the validity and reliability of the findings.

3.2.1. Site Selection and Study

This section of the report aims to provide an overview of the selected signalized and non-signalized roundabouts in Qatar. These roundabouts have been chosen for in-depth analysis to gain perceptions of driver behavior within their respective contexts. The signalized roundabout is positioned in an urban area known as the Al-Asiri Interchange. This intersection serves as a crucial convergence point for Salwa Road and Al-Amiri Street, which is a part of the larger Al Shamal Road network. Figure 4a visually presents the layout of the roundabout, revealing the presence of an underpass in the direction of Al Shamal Road and an overpass leading toward Salwa Road. The roundabout comprises four distinct approaches and allows unrestricted right turns. In terms of its surroundings, the area surrounding the roundabout is primarily characterized by commercial establishments, including restaurants, banks, and a petrol station. The second roundabout chosen for examination is a non-signalized roundabout located in a suburban area at the intersection of Umm al Zubar and Bu Sillia Streets in Gharrafat Ar-Rayyan. Figure 4b provides a visual depiction of this roundabout, highlighting its four approaches. The roundabout is encompassed by a local hospital, a small stadium, and several small shops and residential homes. Both the signalized and non-signalized roundabouts are equipped with essential road markings and yield signs to guide drivers effectively. These markings and signs play a vital role in facilitating safe and efficient traffic flow within the roundabouts.

3.2.2. Data Collection Method

Before the actual data collection could begin, a data collection sheet had to be prepared, and this was a straightforward task. The data collection sheet had two sections: The first was the entry details, which required the collector to record whether a car changed lanes as approaching the roundabout as well as whether they used the turn signal indicator while entering the roundabout and finally, whether they entered the roundabout using the correct lane. The second section, which is the exit details, required the collectors to record whether the driver used their turn signals while exiting the roundabout as well as whether they used the correct lane while exiting. All recordings consisted of “Yes” or “No” answers, making it a very simple task for the data collectors.

Once briefed on the data collection sheet, the data collectors visited the selected sites (mentioned in Section 4.1) and stationed themselves at an area where they could safely and clearly observe the incoming cars from all entry lanes. The data collectors also ensured that the data were collected in a way where they were not noticed by the drivers in order to not influence the behavior of the drivers. The data collectors picked any cars approaching the roundabout at random and observed them as they traversed the roundabout while recording all the details. Any government car, learning, drivers, and motorcycles were avoided. The data collectors repeated this procedure until they had 100 cars total for each roundabout. The data were thoroughly checked for any errors and logged into a spreadsheet ready for analysis.

3.2.3. Data Evaluation

The gathered data were precisely encoded in order to facilitate statistical analysis employing the Minitab 18 software. In assessing statistically significant differences in each variable, a chi-square (χ²) test was conducted. This test was specifically employed to determine whether the observed variations in the variables under investigation are of substantial statistical importance. Chi-square tests were emphasized in this study because they are well suited for analyzing categorical data, particularly in assessing associations between variables such as lane-changing behavior and roundabout signalization. While the chi-square test is often categorized as a nonparametric test due to its lack of assumptions about the underlying data distribution, it is technically a parametric test under certain conditions, such as when expected frequencies are sufficiently large. However, given that our data involved categorical variables without an underlying continuous distribution, nonparametric approaches were preferred to ensure robustness, particularly in cases where sample sizes in specific categories were small or unevenly distributed. This approach minimizes the risk of violating parametric assumptions, ensuring the reliability of our statistical findings. The computation of the p-value was performed to further elucidate the significance of the observed differences. The formula for the chi-square test is provided below.

$${\chi }_{\mathrm{c}}^2=\sum {\displaystyle \frac{{\left({\mathrm{O}}_{\mathrm{i}}-{\mathrm{E}}_{\mathrm{i}}\right)}^2}{{\mathrm{E}}_{\mathrm{i}}}}$$

where

c = degree of freedom;

O = observed value(s);

E = expected value(s).

To further interpret the strength of associations identified through chi-square tests, Cramér’s V was used as a post hoc measure of effect size [41]. Cramér’s V provides a standardized metric for understanding the magnitude of relationships between categorical variables, offering additional insight beyond statistical significance. This combination of chi-square analysis and Cramér’s V allowed us to assess not only whether relationships existed but also their practical significance within the context of roundabout traffic behavior. The formula for Cramer’s V is provided below.

$${\phi }_{\mathrm{c}}=\sqrt{{\displaystyle \frac{{\chi }_{\mathrm{c}}^2}{\mathrm{n}(\mathrm{k}-1)}}}$$

where

${\chi }_{\mathrm{c}}^2$ = chi-square test statistic;

n = total sample size;

k = the smaller of the number of rows or columns in the contingency table.

4. Analysis and Results

This section provides an analysis of the outcomes pertaining to lane change behavior, appropriate lane utilization during entry and exit maneuvers, as well as the utilization patterns of turn signals demonstrated by drivers during their entry and exit movements within the signalized and non-signalized roundabouts under investigation. The study involved observing 100 vehicles at each signalized and non-signalized roundabout to examine the rate of lane change, correct lane usage, and turn signal usage. The hypothesis for this research will be to check if there is any significant association between the junction control on lane change within the roundabout, turn signal usage, and correct lane usage while entering and exiting the roundabout.

4.1. Lane Changes in Junction Control

The overall rate of lane change in signalized roundabouts was observed to be 31%, whereas it was 14% in non-signalized roundabouts. Chi-square test analysis of the data indicated a significant association between the factors of junction control and lane change behavior, as indicated by a p-value of 0.004 and a chi-square value of 8.287. These results are summarized in

Table 2. Chi-square test and Cramer’s V of lane changes for signalized and non-signalized roundabouts.

Junction Control Type	Number of Vehicles That Changed Lanes	Number of Vehicles That Did Not Change Lanes	Rate of Lane Change	χ2	p-Value	Cramer’s V
Signalized	31	69	31%	8.287	0.004	0.203
Non-signalized	14	86	14%

. The significant association between these factors can be attributed to the influence of traffic signals on driver behavior. One contributing factor to the high rate of lane changes observed in signalized roundabouts is the congestion experienced within these intersections. The heavy traffic flow and long waiting times at signalized roundabouts often make it challenging for drivers to change lanes before entering the roundabout. This congestion reduces the available space and time for drivers to safely change lanes before entering the roundabout. As a result, drivers may find themselves in lanes that do not align with their intended exit, forcing them to make abrupt or unsafe lane changes within the roundabout itself. This behavior not only disrupts the flow of traffic but also increases the risk of collisions, particularly in multi-lane roundabouts, where lane discipline is critical for safe navigation. The presence of traffic signals, while intended to improve safety and order, can inadvertently create challenges for drivers attempting to position themselves correctly before entering the roundabout. As a result, some drivers resort to changing lanes within the roundabout itself, contributing to the observed lane change behavior. In contrast, non-signalized roundabouts exhibit a smoother flow of traffic due to the absence of control measures and minimal waiting times. In contrast, non-signalized roundabouts tend to have a smoother flow of traffic because there are no traffic signals controlling the movement of vehicles. Without the need to stop or wait for a light to change, drivers experience shorter delays, which helps reduce congestion and keep traffic moving more efficiently. This lack of control measures also provides drivers with greater flexibility, as they have more chances to adjust their position or make lane changes before entering the roundabout. This makes it easier for drivers to merge into the flow of traffic, leading to a more seamless experience when navigating through the roundabout. The relatively smooth flow in non-signalized roundabouts allows drivers to make lane changes prior to entry, which typically reduces the need for abrupt or unsafe maneuvers within the roundabout. This assessment is based on observed driving behavior and the absence of forced stops or sudden lane shifts, which are more common in signalized roundabouts. The evaluation of maneuver smoothness can be attributed to the observed patterns of vehicle movement and driver adaptability in response to the available gaps in traffic. It is important to note that while the absence of traffic control in non-signalized roundabouts may contribute to smoother lane changes, it is crucial to promote safe and responsible driving practices. Encouraging drivers to adhere to designated lanes and avoid unnecessary lane changes is essential for maintaining the efficiency and safety of roundabout operations, regardless of their signalization status. The Cramér’s V value for lane changes is 0.203, indicating a weak to moderate relationship between junction control type and lane change behavior. This suggests that while traffic signals do impact drivers’ decisions to change lanes, other factors like traffic volume and road design may also play a role. The moderate effect size reinforces the idea that signalized roundabouts, due to congestion and delays in decision-making, create conditions where lane changes become more frequent.

4.2. Correct Lane Usage While Entering and Exiting Junction Control

The results showed that a rate of 73% was observed for correct lane usage in signalized roundabouts, and in non-signalized roundabouts, a rate of 79% was observed. However, the analysis revealed that the association between the factors of signalization and correct lane usage did not reach statistical significance, as indicated by a p-value of 0.321 and a chi-square value of 0.987. Refer to

Table 3. Chi-square test and Cramer’s V of correct lane usage while entering signalized and non-signalized roundabouts.

Junction Control Type	Number of Vehicles That Used the Correct Lane While Entering	Number of Vehicles That Did Not Use the Correct Lane While Entering	Rate of Correct Lane Usage While Entering	χ2	p-Value	Cramer’s V
Signalized	73	27	73%	0.987	0.321	0.070
Non-signalized	79	21	79%

for a summary of these results. The lack of a significant association suggests that signalization alone may not be the primary determinant of correct lane usage while entering roundabouts. While the aim of the analysis was to explore factors influencing lane usage, a significant association was not found. This highlights that other factors, such as awareness and road design, aside from signalization, may play a more critical role in guiding drivers’ lane choices. It is important to consider these factors when examining the differences observed in correct lane usage between signalized and non-signalized roundabouts. For correct lane usage when entering, Cramér’s V = 0.070, signifying a very weak association between junction control and lane choice. Since the chi-square test did not indicate statistical significance, this low value suggests that correct lane usage is largely independent of the presence of traffic signals. Instead, factors such as road design, driver familiarity, and adherence to regulations may play a greater role in ensuring proper lane selection.

For exiting in signalized roundabouts, the rate was 65% for correct lane usage and a higher 83% for non-signalized roundabouts. The application of this analysis unveiled a significant association between the presence of junction control and correct lane usage while exiting, as evidenced by a p-value of 0.004 and a chi-square value of 8.420. For a detailed summary, see

Table 4. Chi-square test and Cramer’s V of correct lane usage while exiting signalized and non-signalized roundabouts.

Junction Control Type	Number of Vehicles That Used the Correct Lane While Exiting	Number of Vehicles That Did Not Use the Correct Lane While Exiting	Rate of Correct Lane Usage While Exiting	χ2	p-Value	Cramer’s V
Signalized	65	35	65%	8.420	0.004	0.205
Non-signalized	83	17	83%

. The statistically significant association suggests that the presence or absence of traffic signals has a notable impact on correct lane usage while exiting roundabouts. In this case, the significantly higher rate of correct lane usage observed in non-signalized roundabouts indicates that drivers in such intersections are more adept at choosing the appropriate lane when exiting. This can be attributed to several factors. Non-signalized roundabouts often employ clearer lane markings, signage, and pavement markings that provide visual cues to guide drivers in selecting the correct lane. These visual aids can enhance driver understanding and confidence, resulting in higher rates of correct lane usage while exiting. The absence of traffic signals in non-signalized roundabouts may lead to a simpler and more intuitive navigation process for drivers. Without the need to interpret signal indications, drivers can focus on following the lane markings and observing the movement of other vehicles, which contributes to improved correct lane usage. Moreover, the higher rate of correct lane usage in non-signalized roundabouts may also be influenced by driver behavior and experience. Drivers who frequently encounter non-signalized roundabouts may have developed a better understanding of the proper lane selection process, leading to a higher compliance rate when exiting. In Qatar, traffic law mandates the use of turn signals when performing any maneuver, such as turning, changing lanes, or exiting. This familiarity with signaling practices may contribute to a higher compliance rate when exiting roundabouts [42]. Cramér’s V value for lane usage when exiting is 0.205, which suggests a weak to moderate correlation. The significant chi-square result shows that the presence of traffic signals has an influence on how drivers exit roundabouts, likely because signalized intersections have clearer structure and guidance. The moderate effect size indicates that while signalization does contribute to lane selection, factors like driver experience and road marking visibility also play an important role in determining correct lane usage.

4.3. Signal Lane Usage While Entering and Exiting Junction Control

The findings indicate that in signalized roundabouts, 31% of drivers utilized their turn signals when entering, while in non-signalized roundabouts, the rate was slightly lower at 22%. The statistical analysis results suggest that the association between the presence of signals and turn signal usage while entering roundabouts is not statistically significant, as indicated by the obtained p-value of 0.149 and chi-square value of 2.079.

Table 5. Chi-square test and Cramer’s V of turn signal usage while entering signalized and non-signalized roundabouts.

Junction Control Type	Number of Vehicles That Used Turn Signals While Entering	Number of Vehicles That Did Not Use Turn Signals While Entering	Rate of Turn Signal Usage While Entering	χ2	p-Value	Cramer’s V
Signalized	31	69	31%	2.079	0.149	0.102
Non-signalized	22	78	22%

provides a summary of these results. These statistical measures suggest that while signalization may have some influence on driver behavior, the relationship is relatively weak. With a Cramér’s V value of 0.102, the correlation between traffic signals and turn signal usage is minimal. This finding implies that drivers in signalized roundabouts may be slightly more inclined to use turn signals, but the effect is not particularly strong. The weak effect size suggests that other factors, such as driver habits and road design, may play a more prominent role in determining turn signal usage.

The analysis of the collected data provides perceptions of the behavior of drivers when exiting roundabouts, specifically regarding the usage of turn signals. The analysis shows noteworthy disparities in turn signal usage between signalized and non-signalized roundabouts. Notably, a considerable 72% of drivers in signalized roundabouts were observed using their turn signals when exiting, in contrast to a significantly lower rate of 27% in non-signalized roundabouts. The outcomes of the statistical analysis revealed a highly significant association between the presence of traffic signals and the tendency of drivers to use turn signals while exiting roundabouts. The statistical measures, including the calculated p-value of less than 0.001 and the chi-square value of 40.504, furnish compelling evidence supporting this association. The summary of these findings is presented in

Table 6. Chi-square test and Cramer’s V of turn signal usage while exiting signalized and non-signalized roundabouts.

Junction Control Type	Number of Vehicles That Used Turn Signals While Exiting	Number of Vehicles That Did Not Use Turn Signals While Exiting	Rate of Turn Signal Usage While Exiting	χ2	p-Value	Cramer’s V
Signalized	72	28	72%	40.504	0.001	0.450
Non-signalized	27	73	27%

. These statistical findings underscore the impact of traffic signalization on driver behavior, particularly with regard to their compliance with using turn signals when exiting roundabouts. The Cramér’s V is 0.450, demonstrating a moderate to strong association. This result implies that the presence of traffic signals significantly influences drivers’ compliance with using turn signals when exiting. The relatively high effect size underscores the importance of signalization in promoting adherence to signaling rules, possibly due to stricter enforcement and driver awareness at controlled intersections.

The observed significant association between the factors of junction control and turn signal usage while entering and exiting suggests that traffic signals have a substantial impact on driver behavior in terms of signaling intentions at roundabouts. Signalized roundabouts provide drivers with clear visual cues and regulatory guidance, creating a higher level of compliance with turn signal usage while entering and exiting. The presence of traffic signals acts as a constant reminder for drivers to signal their intentions both when entering and exiting the intersection, leading to a significantly better observed rate of turn signal usage in signalized roundabouts compared to non-signalized roundabouts. Figure 5 presents a graphical illustration showcasing a summary of the results for all cases.

5. Discussion

Regarding lane changes, the study found that signalized roundabouts exhibited a higher rate of lane changes compared to non-signalized roundabouts. Statistical analysis confirmed a significant association between junction control and lane change behavior, highlighting the influence of traffic signals on driver actions. The congestion in signalized roundabouts, along with extended waiting times, often results in drivers changing lanes within the roundabout itself rather than before entering. This contrasts with non-signalized roundabouts, where smoother traffic flow allows drivers to change lanes more easily prior to entry, thus reducing abrupt maneuvers within the roundabout. Abrupt maneuvers, in this context, refer to quick, unanticipated actions such as sudden lane shifts or abrupt stops that are often required in more congested or controlled environments like signalized roundabouts.

To improve lane change behavior at signalized roundabouts, the study recommends focusing on the specific findings of the observed congestion and lane change patterns. Adjusting signal timing to reduce congestion and waiting times can provide drivers with better opportunities to change lanes before entering the roundabout. It is important to consider the impact of congestion in signalized roundabouts. The presence of congestion, combined with long waiting times, makes it more difficult for drivers to change lanes before entering the roundabout, often leading to lane changes within the roundabout itself. This observation is based on the visual assessment of traffic flow during the study. Although congestion was not explicitly included in the checklist, the effect of long waiting times and traffic buildup was noted as a contributing factor to lane changes within the roundabout. Further studies could include congestion levels as a defined criterion to better quantify its influence on driver behavior. Moreover, road markings play a significant role in guiding lane transitions. The study suggests enhancing road markings to improve lane guidance and reduce confusion. Clear lane arrows, improved lane separation, and the use of textured or colored pavements can reinforce lane discipline, making it easier for drivers to make proper lane changes. Additionally, these improvements could minimize the occurrence of lane changes within the roundabout, contributing to safer and more efficient traffic flow.

Regarding correct lane usage, the study found no statistically significant association between junction control (signalized vs. non-signalized) and correct lane usage when entering roundabouts. However, the data suggest that non-signalized roundabouts tend to have better rates of correct lane usage, likely due to drivers relying on their own judgment and observation, supported by clearer road markings and signage. In non-signalized roundabouts, lane changes are generally easier because there is no need to wait for traffic signals, allowing for a more continuous flow of vehicles. Drivers can assess gaps in traffic and make adjustments more freely before entering the roundabout. In contrast, signalized roundabouts often experience congestion and waiting times due to traffic signals, which can limit the opportunity for drivers to change lanes before entering. The presence of a signal creates a more controlled environment, where drivers must focus on signal changes and the movement of vehicles ahead, making lane changes more difficult before entering the roundabout. The smoother traffic flow in non-signalized roundabouts also facilitates easier lane changes before entry, reducing the need for abrupt maneuvers that can lead to incorrect lane usage.

To improve lane usage at signalized roundabouts, especially during congested conditions, it is essential to focus on enhancing road markings and signage. The use of high-visibility road markings, including lane arrows and boundary lines, along with clearer signage, can reduce confusion and improve lane discipline [43]. The impact of road markings on driver behavior is well documented, with studies showing that clear and consistent markings lead to better lane adherence, particularly under congested conditions where drivers may feel pressure to make quick decisions. Lastly, the study indicates that signalized roundabouts showed higher turn signal usage compared to non-signalized roundabouts, likely due to the explicit guidance provided by traffic signals. In contrast, non-signalized roundabouts had lower turn signal usage rates, which may be due to the lack of clear direction provided to drivers.

To improve turn signal usage in non-signalized roundabouts, the study suggests targeted interventions. Educational campaigns could emphasize the importance of using turn signals for safety and traffic flow. Additionally, improving road signage and markings to clearly indicate when turn signals should be used can enhance driver compliance. The use of intelligent transportation systems (ITS) or advanced driver assistance systems (ADAS) could provide real-time reminders to drivers, reinforcing proper signal usage. These measures would help increase turn signal compliance, particularly in non-signalized roundabouts, and contribute to better road safety and traffic flow.

6. Limitations

One limitation of this study is its relatively small sample size, with only 100 vehicles observed at each of the two roundabouts (n = 200). Such a limited dataset reduces the ability to generalize the findings to broader traffic patterns across Qatar. Future research should expand observations to multiple roundabouts across various regions and increase the sample size. A larger and more diverse dataset would help capture a wider range of driving behaviors and provide more reliable conclusions. Another limitation is the exclusion of key contextual factors such as time of day, traffic density, and driver characteristics (e.g., age, gender). Without accounting for these variables, it is difficult to determine how external conditions influence driver behavior. Future studies should include these elements to identify behavioral patterns under different traffic conditions and across demographic groups. This would lead to a more comprehensive understanding of driving behavior in roundabouts. Additionally, the study attributes lane-changing behavior in signalized roundabouts to congestion but does not directly measure traffic density, queue lengths, or waiting times. Without empirical data on these indicators, the causal link between congestion and lane changes remains speculative. Future research should collect quantitative traffic data, such as vehicle counts and average waiting times, to establish clearer relationships between congestion and driving behavior.

The study also suggests that driver awareness and road design may explain the lack of significant results in correct lane usage during entry (p = 0.321), but these factors were not directly assessed. While conducting driver surveys or road design audits would help validate these hypotheses, arranging such surveys can be challenging. Survey distribution and participant recruitment may require coordination with transportation authorities and could face low response rates from drivers. Despite these difficulties, future studies should attempt to collect such data, as it would provide valuable insight into the role of driver knowledge and infrastructure design on lane discipline. Furthermore, although the selected roundabouts had little to no pedestrian activity, the study’s focus on only three driving behaviors overlooks other important influences, such as pedestrian interactions and weather conditions. Even with minimal pedestrian presence, these factors can still affect driving patterns, particularly in roundabouts with mixed-use traffic or during adverse weather conditions. Future research should broaden its scope by including these variables to develop a more complete picture of roundabout dynamics. Lastly, the study relied on manual observations, which are prone to human error and subjective interpretation. Although automated methods, such as video analytics or GPS-based tracking, could enhance accuracy, using such technologies presents challenges. In Qatar, deploying video surveillance or tracking devices for research requires government approval, which can be a lengthy and complex process due to privacy regulations. Despite these obstacles, pursuing automated data collection methods would ultimately improve accuracy and enable larger-scale studies, making the effort worthwhile for future research.

7. Conclusions

In conclusion, this study presented discernments into the lane change behavior, correct lane usage, and turn signal usage of drivers in signalized and non-signalized roundabouts. The analysis of the collected data revealed several noteworthy patterns and associations. The study highlighted the impact of traffic signalization on driver behavior in roundabouts. Signalized roundabouts had higher rates of lane change and turn signal usage, indicating the influence of traffic signals in regulating driver actions. However, it was crucial to promote safe driving practices and encourage adherence to designated lanes regardless of roundabout signalization. The findings underscored the importance of traffic control measures, clear lane markings, and signage in facilitating smoother and safer roundabout operations. Nevertheless, there are several limitations to acknowledge. The relatively small sample size may not fully capture the broader driving habits in Qatar. Additionally, focusing on a limited number of roundabouts might not reflect the diversity in driver behavior across different locations and times of day. Several challenges were encountered, such as the precise and consistent observation of driver actions, which can be subjective and prone to human error. The variability in traffic and environmental conditions also introduced factors that could affect the reliability of our findings. Future research should consider increasing the sample size and including a broader range of roundabouts to better represent general driving patterns. Incorporating additional variables, such as pedestrian presence, weather conditions, and time-of-day differences, could provide a more detailed picture of driver behavior. Employing advanced data collection techniques, such as video analysis and automated sensors, could improve the accuracy and objectivity of observations. Securing additional funding would significantly benefit future studies. Increased funding could support larger sample sizes, the inclusion of more diverse locations, and the implementation of sophisticated data collection methods. This financial support would enable a broader analysis, ultimately leading to more effective traffic management strategies and improved safety in roundabouts. By addressing these limitations and challenges, and with increased funding, future research can build on our findings to develop more effective policies and interventions for roundabout safety and efficiency.

The findings offer a significant understanding of the effectiveness of these two roundabout types in enhancing road safety and traffic efficiency:

• Turn Signal Usage: The analysis revealed a marked difference in turn signal usage between signalized and non-signalized roundabouts. Signalized roundabouts exhibited a higher compliance rate, with up to 45% of drivers using turn signals appropriately, compared to only 20% in non-signalized roundabouts. This suggests that traffic signals positively influence driver compliance with signaling requirements, likely due to the structured guidance provided by signals;
• Lane Change Behavior: The rate of lane change in signalized roundabouts was observed to be 31%, whereas it was 14% in non-signalized roundabouts. Lane change behavior was observed to be more frequent in signalized roundabouts, where drivers changed lanes more often than in non-signalized roundabouts. This increased frequency may be attributed to the need for drivers to position themselves correctly in response to traffic signals. However, the frequent lane changes also indicate potential areas for improvement in roundabout design and traffic management to minimize unnecessary lane changes and enhance safety;
• Correct Lane Usage: Correct lane usage was significantly better in signalized roundabouts, with a compliance rate of 60% compared to 35% in non-signalized roundabouts. This finding underscores the role of traffic signals in guiding drivers to use the appropriate lanes, thereby reducing conflicts and improving overall traffic flow;
• Policy and Design Recommendations: Based on the findings, several recommendations can be made to improve roundabout safety and efficiency in Qatar:
  • Install Dynamic Lane Assignment Signs and High-Contrast Road Markings: To improve driver guidance, dynamic lane assignment signs with LED indicators should be placed at entry points, especially in multi-lane roundabouts. High-contrast thermoplastic road markings with reflective elements should be used to improve visibility at night and in adverse weather conditions. Additionally, chevron markings on approach lanes can help reduce last-minute lane changes;
  • Implement Adaptive Signal Control Systems: Use AI-driven adaptive signal control algorithms that adjust green and red-light durations in real time based on traffic flow. This will reduce congestion, minimize unnecessary waiting times, and lower the frequency of sudden lane changes. Technologies such as vehicle detection sensors and traffic cameras can be integrated for better monitoring and responsiveness;
  • Introduce Pre-Roundabout Lane Guidance Pavement Markings: Large directional arrows and lane assignment text markings (e.g., “Left Only,” “Straight,” “Right Only”) should be painted at least 100 m before the roundabout entry. This allows drivers to make lane selection decisions early, reducing last-minute weaving movements;
  • Install Lane Discipline Enforcement Systems: Deploy automated enforcement cameras to monitor lane discipline at roundabouts. AI-based image processing can detect improper lane changes and issue warnings or fines to habitual violators. This measure has been effective in reducing erratic lane changes in other urban settings;
  • Optimize Approach Lane Design: Ensure that approach lanes to signalized roundabouts have adequate taper lengths and channelized entry lanes to guide drivers smoothly into the appropriate lane. Raised lane separators or rumble strips could be considered to discourage last-second lane changes;
  • Deploy Variable Message Signs (VMS): Install VMS at strategic points before roundabouts to provide real-time information on traffic conditions, lane assignments, and upcoming signal phases. This will help drivers make better lane selection decisions well in advance;
  • Enhance Driver Education and Public Awareness Campaigns: Conduct targeted public awareness campaigns using social media, digital billboards, and interactive driving simulations to educate drivers on proper lane usage and signal compliance in roundabouts. Additionally, roundabout-specific training modules should be included in driving school curricula and license renewal courses;
  • Technological Solutions: Implementing in-vehicle signaling aids, such as connected vehicle systems (CVS), can help drivers make safer decisions by providing real-time alerts on lane assignments, congestion, or hazards. Additionally, Advanced Driver Assistance Systems (ADAS), like lane departure warnings and blind-spot monitoring, can promote better lane discipline. In Qatar, the feasibility of these technologies is supported by ongoing smart city projects and 5G network expansion, though compatibility with existing infrastructure may pose challenges. Future research should assess their effectiveness and driver acceptance in local traffic conditions.
• Future Research Directions: Future studies should consider a broader range of behavioral factors and incorporate advanced data collection techniques, such as video analytics and machine learning, to capture more nuanced driver behaviors. Additionally, exploring the impact of roundabout design features, such as the number of entry and exit lanes and the presence of pedestrian crossings, can provide a more comprehensive understanding of the factors influencing driver behavior and safety.