Xiaohua Zhao

Beijing University of Technology | Bei Gong Da · transportation research center

Objectives: With the rapid development of expressways in the mountainous regions of southwestern China, closely spaced tunnel-interchange structures have inevitably emerged due to topographical constraints and environmental limitations. Given the unfavorable road geometry and rapid cross-section transitions, drivers face significant safety concern...

The driving test is the only way to verify that learner drivers have acquired the competencies stipulated in the national curriculum. Therefore, exploring the key factors that influence the outcome of the driving test is of particular importance in assisting learner drivers to gain solid behind-the-wheel skills. Interpretable machine learning (ML)...

Traffic conflict commonly occurs in intersections with offset lane lines because of mismatched choices of entrance and exit lanes. This conflict drives down overall traffic efficiency and can cause crashes. At such intersections, the driver’s lane choice behavior seriously affects the traffic system. The theory of planned behavior (TPB) was used in...

The airport road traffic sign system is essential for drivers to find their destinations. However, no comprehensive design standards have been established for airport roadway traffic signs in China. An airport roadway traffic sign system was designed based on the Chinese Road Traffic Signs and Markings standard (GB5768-2009), called scheme 1. A sec...

The change of space environment at the tunnel entrance which the light changes from bright to dark will lead to frequent traffic accidents. To explore whether the connected vehicle environment will improve the driving performance and traffic safety at the tunnel entrance, this paper first of all designed a driving simulation experiment and provided...

To investigate the optimal method of the complex diagrammatic guide signs (DGSs), a typical complex DGS is selected, and five alternatives are considered, including the current situation (CS), repetition (RT), simplification (SF), pavement words (PW), and advance placement (AP). This study conducts a driving simulation experiment and develops a com...

Introduction: To promote the safety level of ride-hailing services, this study develops the Targeted and Differentiated Optimization Method of Risky Driving Behavior Education and Training (TDOM-RDBET) founded on driver type classification of high-risk drivers. Method: Based on value and goal orientations, 689 drivers were classified into four d...

Facing the currently large quantity of intelligent transportation data, missing ones is often inevitable. Some previous works have shown the advantages of tensor decomposition-based approaches in solving multi-dimensional data imputation problems. However, a research gap still exists in examining the effect of applying these methods on imputation p...

This research investigates the impacts of the driver’s risky driving behavior on traffic crash risk detection by constructing four models, including models with and without the use of risky driving behavior data before and during crash. The major findings are as follows. First, the accuracy of the model was improved by adding risky driving behavior...

The cooperative vehicle-infrastructure system (CVIS) offers opportunities to further enhance the potential of energy saving and emission reduction for eco-driving. However, it is still not clear about the effectiveness of CVIS on promoting eco-driving nor the multivariate effectiveness of CVIS designed for eco-driving on traffic flow and safety cha...

In automated driving, takeover behavior is crucial to safe transition of control. Based on this fact, the goal of the present study is to construct the driver's takeover behavior mode and verify its effectiveness. In the takeover process, we define the takeover behavior mode, which is the inherent mode of completing the takeover task, as the behavi...

Since a tunnel is dark and driving conditions are monotonous, drivers are prone to optical illusions, affecting driving safety in tunnels. Tunnel sidewall decorations can provide visual stimulation to prevent or reduce traffic crashes. Driving simulation experiments with a driving simulator and speed perception experiments with E-Prime software are...

The foggy freeway is a scenario with a high incidence of accidents. Different traffic flow conditions will affect the driving behavior of conditionally autonomous vehicle drivers in the foggy areas of the freeway. In this study, the experiment was carried out by using the driving simulation system. Forty-two participants drove on a foggy freeway ac...

With the rise of the transportation mode of shared electric bikes (shared e-bikes) in China, shared e-bike related accidents have gradually increased. To facilitate the design of safety policies, it is important to understand the factors that influence shared e-bike riders’ traffic accidents to facilitate intervention strategies. For this purpose,...

Considering the fact that driving behavior data possesses characteristics of strong real-time, poor stability, and continuous change, this study proposes the Individual Driving Behavior Graph Construction Method (DBGCM), which visually presents the time trajectory of driving behavior to explore safety-ecological (SAF-ECO) characteristics of individ...

This study explores the influence of cooperative vehicle infrastructure system (CVIS) on the driver’s visual and driving performance. Taking the work zone as an example, a driving simulation experiment involving 37 drivers has been conducted to collect driver’s eye movement and vehicle running data in the same scenario with and without CVIS informa...

Investigating the acceptance of augmented reality head-up displays (AR-HUD) in connected environments is an important research issue as there is great potential to enhance driving safety for both manual and autonomous driving. This study investigated drivers’ acceptance of AR-HUD with the extended technology acceptance model (TAM) with extended var...

To clarify the effect of the cooperative vehicle infrastructure system (CVIS) application on drivers’ visual performance, a total of 37 drivers were recruited to drive the simulated roadway in a freeway work zone under baseline and cooperative vehicle environments. Drivers’ attention and concentration on the forward roadway, attention distraction,...

As an emerging approach, driving simulator plus VR has been gradually applied in the field of driving training. There is still a lack of scientific and comprehensive methods to evaluate the effectiveness of this. Through integrating the training data of 119 driving school students, the research adopts a hierarchical evaluation method to assess the...

Due to the burgeoning demand for bike sharing usage, bike sharing related urban management issues have been growing substantially. This article used data from the Beijing region in 2019 to explore the relationships between the weather factors and cycling demand, and predicted the demand of bike sharing using XGBoost. Then, SHAP was employed to inte...

To provide a better understanding of individual driver’s driving style classification in a traditional and a CV environment, spatiotemporal characteristics of vehicle trajectories on a road tunnel were extracted through a driving simulator-based experiment. Speed, acceleration, and rate of acceleration changes are selected as clustering indexes. Th...

As a novel traffic safety facility, the decorated sidewall in tunnels plays a crucial role in improving the safety and upgrading the driving environment. The design element spacing, frequency patterns and color, are important elements in the design of the tunnel wall decoration. In order to analyze the impact of the tunnel sidewall decoration eleme...

To verify whether a graph is suitable for describing driver behaviour performance under the effects of navigation information, this study applies two types of prompt messages: simple and detailed. The simple messages contain only direction instructions, while the detailed messages contain distance, direction, road and lane instructions. A driving s...

To further enhance the role of connected vehicles with the Human-Machine Interface (HMI) in helping drivers in foggy weather, it is meaningful to optimize the HMI based on the driver’s needs. In order to explore the method of HMI optimization, this paper builds a driving simulation experimental test platform of freeway connected vehicle system, des...

Because of heavy traffic on urban expressways, the exits of expressway interchanges have become accident-prone sites. This study explores the impacts of various traffic control devices and road conditions on road safety at interchange exits based on driving behavior data from navigation software. The traffic order index (TOI) based on driving behav...

Fog often occurs on freeway bridges crossing rivers, reducing the drivers’ visibility and increasing the vehicles’ braking distance. Setting a reasonable speed limit under foggy conditions is required to ensure safe driving on freeway bridges. The traffic status also affects the speed limit in foggy conditions. Different from most existing variable...

Most of the safety studies mainly takes the probability of crashes or relevant records as the main indicators. Accident-based safety analysis may lead to overestimation or underestimation of traffic risks, which are delayed and sparse. Aggressive driving behavior is one of the major causes of traffic accidents, which can accurately measure traffic...

This paper proposes a novel fuzzy comprehensive evaluation model based on the 2-tuple linguistic model and grey target decision method (2TL-GTD) for evaluating the comprehensive application effect of the connected vehicle system. Since the evaluation indicator system of the research problem belongs to multi-source heterogeneous data, the original d...

In light of the increasing amount of traffic disorder at road traffic hubs, to improve traffic safety, it is essential to detect road risks in advance and analyze the causes after its occurrence. In this study, interpretable machine learning (ML) is employed to analyze the traffic order by using a set of multi-source data comprising traffic conditi...

Introduction: As China has recently lifted the age limit for getting access to driving licenses, older drivers' safety issues have received wide attention. Driving self-regulation can be regarded as an adjustment strategy for older adults to reduce risks and extend driving lives. Studies abroad mainly stress the three levels and influencing factor...

Traffic crash detection is a promising and challenging research topic. Due to the limitations of data collection, previous studies mainly used traffic flow variables to establish a traffic crash detection model, and the contribution of risky driving behavior to the traffic crash detection model was not clear. The widespread application of traffic d...

Introduction: Urban expressway interchanges have become accident-prone sites owing to the accelerated increase in motor-vehicle ownership. This study explored the impact of factors, including day of the week, time of day, congestion level, traffic control devices, and road conditions, on road safety risk levels in the interchange area of an urban...

Changes in driving behavior caused by reduced visibility in fog can lead to crashes. To improve driving safety in fog weather, a fog warning system based on connected vehicle (CV) technology is proposed. From the perspective of human factors, this study evaluates the driving safety based on drivers’ speed change under different fog levels (i.e., no...

To ensure safety, it is necessary to test the connected vehicle (CV) technology before application. The goal of this study is to provide a case reference for the testing of the connected vehicle technology. The connected vehicle technology test platform is built based on the driving simulator. Taking fog zone, tunnel zone, and work zone as analysis...

The prediction of traffic crashes is an essential topic in traffic safety research. Most of the previous studies conducted experiments on real-time crash prediction of expressways or freeways, based on traffic flow data. However, the influence of risky driving behavior on traffic crash risk prediction has rarely been considered. Thus, a traffic cra...

In China, F-type-5 m intersections are not uncommon. One approach of these intersections usually includes a driveway closely followed by an intersecting street, and the driveway and the intersecting street are parallel and approximately 5 m apart. Nowadays, drivers often rely on the navigation systems for directions. However, it is found that the n...

An audio navigation system is a very useful tool for driving path guidance with less distraction. However, the influence of the audio navigation system on driver behavior, especially in complicated road environments, is still not entirely clear. This study aims to investigate navigation prompt timing (NPT), navigation prompt message (NPM), and thei...

Purpose Heavy fog results in low visibility, which increases the probability and severity of traffic crashes, and fog warning system is conducive to the reduction of crashes by conveying warning messages to drivers. This paper aims at exploring the effects of dynamic message sign (DMS) of fog warning system on driver performance. Design/methodolog...

The drastic changes of the space environment at the tunnel entrance can lead to frequent accidents with higher levels. The connected vehicle environment provides drivers with surrounding traffic information and improve their driving behavior by helping them make safe decisions efficiently. As such, this study is to examine the effects of the connec...

To develop a scientific and practicable guideline for implementing warning piles on Chinese low-grade highways, it is necessary to study the effect of warning piles on driving performance in different road alignments and environments. Based on a driving simulator, this paper evaluates the effect of unilateral and bilateral warning piles on vehicle...

Abstract In view of the benefits and a promising prospect of the emerging connected vehicles (CV), more and more vehicles will be equipped with the in‐vehicle human‐machine interface (HMI). This study aims to assess the comprehensive impacts of HMIs on individual driving performance, traffic safety, and eco‐driving behaviour based on a driving simu...

Traffic safety devices are one of the most important tools used to improve safety in tunnels. The tunnel retro-reflective arch (TA) plays a crucial role in stimulating drivers, relieving visual stress, and improving safety. However, determining the TA spacing mostly relies on experience and relevant standards are lacking. The aim of this research w...

The accidents in the freeway are frequent and more serious on foggy days. Connected vehicle (CV) technology as a new technology can inform drivers of fog conditions in advance so the drivers can adjust their driving behaviors through Human Machine Interface (HMI) and Dynamic Message Sign (DMS) in the fog warning system. The level of driver's compli...

In this study, a driving simulator experiment was conducted to investigate the influence of tunnel retro-reflective arch (TA) on driving behavior, through the employment and analysis of TAs with disparate spacing alternatives (no TAs, TAs with a spacing of 200 m, and TAs with a spacing of 300 m) and tunnel lengths (800 m, 1800 m, 3500 m, and 5800 m...

Connected vehicle technology relying on Human Machine Interface (HMI) achieve a dominant position in the overall safety improvement. However, the impact of HMI on the driver’s visual attention cannot be ignored, especially on the accident-prone foggy freeway. The objective of this paper is to evaluate the level of distraction caused by HMI in data...

The research adopted the traffic big data such as driving behavior，maps，traffic conditions and user volume collected by the navigation software to develop a traffic order index and evaluate the road safety risks. By analyzing the traffic safety features of road alignment， traffic control devices，traffic signals at intersection entrance，a structural...

Many diagrammatic guide signs in China have become much more complex and more difficult to read than those in other countries. Furthermore, there are few regulations or studies regarding diagrammatic guide signs in China. A driving simulator experiment was conducted to analyze the influence of five typical diagrammatic guide signs with different co...

According to many studies, motor vehicle collisions lead to many deaths and disabilities, and bring about huge economic losses to societies and individuals around the world. If risky scenarios could be recognized and the driver could be timely warned, the frequency of traffic accidents could be reduced effectively, and traffic safety could be impro...

Raised pavement markers (RPMs) are among the common safety features of roads, playing an important role in preventing and reducing traffic crashes. RPMs are regarded as an effective measure for reducing the high crash rate and mortality in freeway tunnels in China. In this study, a driving simulator experiment was conducted to investigate the safet...

Eco-lanes are an important means of implementing eco-driving behavior and reducing vehicle emissions. Cooperative vehicle infrastructure connected technology offers further energy savings and emission reduction benefits through eco-lanes. Based on the cooperative vehicle infrastructure driving simulator experiment platform, 40 subjects were selecte...

Pedestrian safety is vital, especially when it comes to crossing at intersections. Setting pedestrian safety facilities is one of the solutions to provide a safer environment for pedestrians to cross at intersections. And most studies have focused on the influence of pedestrian safety facilities on drivers’ yielding behavior. Meanwhile, psychologic...

Risk assessment of in-vehicle devices is an important part of the study of distracted driving. In this study, a visual distraction assessment method was formulated based on the AttenD algorithm. Driving simulator experiments were conducted with five secondary tasks including navigation, tuning the radio, replying to a text message, replying to a vo...

This study proposes an integrated technology acceptance model to investigate the factors that affect drivers’ usage intention of mobile navigation applications. The proposed model adds three new constructs (drivers’ sense of direction, navigation application affinity and distraction perception) to the original technology acceptance model based on t...

Emergency braking event of the vehicle in front is one of the main causes of forward collision. If the driver can sense emergency braking events of the vehicles in front timely, the coping behavior can be changed from passive visual stimulation to active coping behavior based on psychological expectation, which will greatly reduce the accident rate...

To provide a better understanding of spatiotemporal characteristics of vehicle trajectories in connected vehicle environment, a driving simulation study was designed and conducted with an extra-long tunnel scenario. 35 drivers were recruited to participate in the driving experiment. To evaluate the spatiotemporal characteristics of vehicles with an...

To provide a better understanding of the effectiveness of the vehicle-road cooperative system on spatiotemporal characteristics of vehicles, especially in a tunnel road, this paper designed the human-machine interface of tunnel warning system based on the connecte