Driving Safety Assurance Method in Work Zone Crossovers of Highway Reconstruction and Expansion Project

Work zone crossover is an important area in highway reconstruction and expansion projects because it profoundly impacts the traffic safety and efficiency of the construction sites. This research sets the different median opening widths in the driving simulation experiment, collects the vehicle control signal parameters during entrance by-pass and exit by-pass, and analyzes the driving characteristics in these sections. Comparison of the driving features between the simulation experiment and the actual driving under the same median width has been also made. We should set the median width separately because the results show that driving behaviors significantly differ between entrance by-pass and exit by-pass. When the median opening width is 70 m, the driving simulation experiment and actual driving characteristics are quite different. However, both show that driving factors of the entrance and exit by-pass are not the same. When there are two lanes in the traffic control zone and the speed limit is 60 km/h, we should set the median width at 90 m to ensure transportation safety.

Application of Cluster Analysis to Define Level of Service Criteria of U-turns at Median Openings

Defining Level of Service (LOS) criteria of U-turns is important for proper planning, design of transportation projects and also allocating resources. The present study attempts to establish a framework to define LOS criteria of U-turns keeping in mind the peculiar behavior of drivers and heterogeneity in urban Indian context. The U-turns at uncontrolled (no traffic sign, no signal, no traffic personnel) median openings are very risky. Upon arrival at the median opening, the U-turning vehicle looks for a suitable gap in the approaching traffic stream before initiating the merging process. While waiting for a suitable gap the U-turning vehicle experiences service delay. This service delay has been studied to quantify the delay ranges for different LOS categories. In this study, service delay data were collected from 7 different sections and microscopic analysis procedure was adopted to extract data from the recorded video. Subsequently, clustering technique has been utilized to defining delay ranges of different level of service categories. Four clustering methods, namely; K-mean, K-medoid, Affinity Propagation (AP), and Fuzzy C-means (FCM) are used. Four validation parameters are applied to determine most suitable clustering algorithm for the study and to determine the optimal number of cluster. AP was found to be the most suitable clustering method and 6 was found to be the optimal number and accordingly the collected delay data were clustered into 6 categories using AP. The delay range is found to be less than 4 s for LOS A is greater than 35 s for LOS F.

The Development of A Versatile Movable Barrier Solution

To reduce the accident risk of work zone on highway, a new movable barrier solution is presented in this paper. The barrier is effective, affordable, environment-friendly and versatile. It can raise the level of highway safety performance in work zone, median opening and tidal lane. The development of the versatile movable barrier took reliability, mobility, economical efficiency, construction convenience into account. Researchers optimized structure by finite element analysis as well as mechanic analysis. The finite element analysis was accomplished by LS-DYNA. This barrier set eventually passed simulated impact tests, which proved that it is able to fulfil the requirement of 160kj-level safety performance.

Analysis of Rear-End Crash on Thai Highway: Decision Tree Approach

Objective. Among crash types on Thai highways, rear-end crashes have been found to cause the largest number of fatalities. This study aims to find ways to decrease rear-end crashes and fatal rear-end crashes. Methods. Classification and regression tree (CART) was used to analyze the complicated relationship of variables of big data. The analysis was conducted by creating two models: (1) a model which indicates the causes of rear-end crashes by applying Quasi-Induced Exposure to at-fault driver characteristics; (2) a determined model which studies fatal crashes. Results. Predictor variables in the model of at-fault and not-at-fault drivers found that driver age is most significant, followed by number of lanes and median opening area. For the mode of fatality, the use of safety equipment was found to be of most importance. Conclusion. The model results can be used to develop guidelines for public awareness programs for motorists and to propose policy changes to the Department of Highway in order to reduce the severity of rear-end crashes. Moreover, this paper discusses the variables that may result in both the perspective of rear-end crash number and the fatality rate of rear-end crashes as strategies in future research.

Traffic Control Devices for Deterring Wrong-Way Movements at Unsignalized Intersections on Divided Highways

Motorists driving the wrong way on divided roadways has been an area of concern for over 50 years. However, little is known about the nature of wrong-way crashes on divided highways. Thus, the research team conducted exploratory and statistical analyses to assess the effects of median width and select traffic control devices upon wrong-way crashes on high-speed divided highways. The exploratory analysis revealed that most of the wrong-way crashes on high-speed divided highways resulted in serious injury and happened at night. More than two-thirds of the wrong-way crashes resulted from a wrong-way maneuver at an intersecting roadway where a median opening was present. The statistical analysis found numerous sites where the traffic control in the median opening did not fully comply with the Manual on Uniform Traffic Control Devices (MUTCD) with respect to treating the location as one or two intersections. There was also evidence from the statistical analysis that the 30-ft median width threshold may not be appropriate for distinguishing between one or two intersections. In addition, researchers were able to identify several traffic control devices that may be effective in reducing wrong-way movements on high-speed divided highways. The final effort of the project was to develop recommended MUTCD language for implementing the research findings. The recommended language includes a new method for distinguishing between divided highway crossings that function as a single intersection or two separate intersections, thereby eliminating the 30-ft median width threshold used in the current MUTCD.