Roundabout Safety Benefits, Design Considerations and Safety Evaluation Techniques

A combined use of microscopic traffic simulation and extreme value methods for traffic safety evaluation

A new method for preclinical evaluation of safety of antiarrhythmic drugs is proposed. During chronic stress, class I antiarrhythmic preparations increased mortality of test animals. By contrast, class II-IV antiarrhythmic agents and antioxidants produced no significant effect on mortality of experimental mice. These data agree with published results of multicenter studies.

With the demand for green mining in coal mines, filling mining is becoming more and more popular, resulting in more complex production systems and more potential safety hazards. Therefore, it is very important to evaluate the safety of filling mining mines and propose improvement measures. Aiming at the safety evaluation method of filling mining mines, this paper innovatively proposes a safety evaluation method based on entropy weight–attribute mathematical theory, which enriches the theoretical research related to the safety evaluation model of filling mining mines. Five secondary indexes and twenty-two tertiary indexes were selected. The weights were determined via the entropy weight method, and then the attribute mathematical theory was used for safety evaluation. The evaluation results show that the safety level of Jisuo Coal Mine is “relatively safe”, and the evaluation results are in good agreement with the actual situation of Jisuo Coal Mine, which verifies the applicability of the attribute mathematical theory. Finally, from the perspective of safety input, the simulation study is carried out by using system dynamics, and the dynamic change rule is analyzed. Additionally, improvement measures for filling mining mine safety are proposed so as to realize the reasonable optimization of resource allocation.

As one of the core objectives of traffic design, traffic safety plays an important role in improving the economic and social benefits of the transportation system. The principles and characteristics of all kinds of traffic safety evaluation methods will be illustrated, from the aspect of evaluation regions and evaluation tools. The specific methods include macroscopic and microscopic safety evaluation and direct and indirect safety evaluation. In addition, the real-time safety evaluation method will be presented, which is under the vehicle-infrastructure collaborative environment and provides new ideas for urban road traffic safety evaluation.

This study focuses on a safety evaluation method for underground gas storage. Gas storage is usually constructed underground in complex environments, and the service life of such facilities is limited. To ensure the secure and long-term operation of gas storage facilities, safety evaluation has become the focus of management. The present paper provides an effective method for safety evaluation. An index system was established as the foundation of the analysis for this evaluation, and the matter-element extension method was applied to obtain a quantitative evaluation result. For the weight values of each index in the matter-element extension method, this paper presents a comprehensive weight computation method based on vague sets and entropy. By application of this method, the safety level of a gas storage facility in the Jintan salt mines (in Jiangsu, China) was calculated, and the evaluation result was 4.6433, which meant the safety level was V and the underground gas storage was slightly at risk. It indicated that the influence on the overall safety and tightness of this gas storage could be ignored in the operation process, but the frequency of regular monitoring should be increased. The defective indexes were also obtained, such as salt rock cohesion, the roof thickness, the volume contraction ratio, the interlayer content, the height of the casing shoe and the adjacent cavity pressure difference, which need to be monitored and modified. This paper evaluated the safety of the underground gas storage from a unique perspective. It is expected that the results of this research will contribute to the maintenance and operational decisions, and provide a reference for management in the energy industry.

The operating environment of perforated strings is highly complex, making their safety a critical concern, particularly when evaluating their performance under shock loading conditions. A simplified model of the perforated string system subjected to shock loading is developed, leading to the formulation of a shock load calculation model. This model is then used to analyze the relationship between peak pressure and axial force under shock loading. Based on field data and commercial software to verify the accuracy of the model, two wells in the Southwest region were evaluated for safety. The results show that, using this model, the peak pipe pressures under shock loading for the two wells are calculated to be 69.52 MPa and 82.93 MPa, respectively. When compared to results from a commercial software for analyzing wellbore dynamics, the error is minimal, suggesting that the model provides accurate calculations and predictions of peak pipe pressure within acceptable error margins. This model meets engineering requirements and can serve as a practical tool for safety evaluation. Overall, the findings demonstrate that the safety evaluation method and calculation model offer valuable guidance for engineering practice and provide a reliable reference for assessing the safety of perforated strings under shock loading conditions.

Real‐time safety evaluation of urban signalized intersections is a prerequisite for proactive traffic safety management. Due to its independence from historical data, the traffic conflict technique has gained increasing popularity as a tool for real‐time safety evaluation in transportation systems. However, different types of conflicts (e.g., rear‐end and side‐impact conflicts) may lead to differences in safety evaluation, which has led previous studies to typically analyze crash risk based on various conflict types separately. Therefore, this study develops the hierarchical Bayesian extreme value theory (block maxima (BM)) model based on different conflict types to form a novel real‐time safety evaluation approach. The proposed model is applied to the real‐time safety evaluation of five signalized intersections in Harbin, China. The results show that (1) the proposed BM model exhibits good prediction performance when there is sufficient observation duration and a sufficient number of samples; (2) the proposed model is superior to other baseline models developed based on only one conflict type in terms of prediction accuracy. The empirical findings of this study establish innovative frameworks and theoretical foundations for advancing proactive safety protocols and autonomous mobility systems.

A safety evaluation method based on an entropy weight method is proposed that is aimed at the features of heavy-duty computer numerical control (CNC) machine tools, such as long-life cycle, complex structure, high cost and many hidden safety risks. According to the risk sources of each phase of the total life cycle, the expert-scoring table is formulated and the process of experts' scoring is developed from the perspective of a “man-machine-environment-workpiece” system. Considering the differences in the experts' scoring, an entropy weight method is used to calculate the weight of each expert at each phase of the total life cycle. The proposed method is applied to the XKA28 heavy-duty CNC gantry milling machine, and the safety evaluation is implemented. The results indicate that the proposed method is feasible.

The establishment of a safety evaluation method is one of the key issues for the nuclear hydrogen production demonstration since fundamental differences in the safety philosophy between nuclear plants and chemical plants exist. In the present study, a practical safety evaluation method, which enables to design, construct, and operate hydrogen production plants under conventional chemical plant standards, is proposed. An event identification is conducted for the HTTR-IS system, a nuclear hydrogen production system by thermochemical water splitting iodine-sulfur process (IS process) utilizing the heat from the high temperature engineering test reactor (HTTR) in order to select abnormal events, which would change the scenario and quantitative results of the evaluation items from the existing HTTR safety evaluation. In addition, a safety analysis is performed for the identified events. The results of safety analysis for the identified five anticipated operational occurrences (AOOs) and three accidents (ACDs) show that evaluating items such as a primary cooling system pressure, temperatures of heat transfer tubes at pressure boundary, etc., do not exceed the acceptance criteria during the scenario. In addition, the increase of peak fuel temperature is small in the most severe case and therefore, the reactor core was not damaged and cooled sufficiently. These results will contribute to the safety review from the government and demonstration of the nuclear production of hydrogen.

Study on mechanical characteristics and safety evaluation method of steel frame structure after fire

Centrifugal compressors are the key equipment in natural gas transportation; therefore, the safety and reliable operation of compressors is of great importance for natural gas transportation. The harsh working conditions and the complex mechanical structure, can easily cause the failure of a centrifugal compressor, and leads to shut down. Therefore, it is necessary to conduct safety evaluation for centrifugal compressors. The conventional safety evaluation methods cannot describe experts' experiences and knowledge accurately, and have calculation defects in risk rating. In order to solve these problems, this study proposed a safe evaluation method based on FMEA-fuzzy reasoning. First, this method performs failure identification of a compressor based on the FMEA method and establishes an expert-failure evaluation model. After that, the fuzzy comprehensive evaluation method is used to perform a quantitative analysis on the model to obtain the failure modes' risk levels, and ultimately determines a compressor's risk level. To verify the proposed method, this study performed a risk evaluation for centrifugal compressors in a compressor station. The results of the evaluation showed that the proposed method had a good application effect.

Due to the serious condition of safety production in hydropower construction project on the whole, it is an urgent need to evaluate hydropower engineering construction safety. But the problem of the mapping relationship between evaluation index and accidents, fixed and variable weight, randomness and fuzziness and so on, can't be solved through the traditional safety evaluation method for hydraulic engineering construction safety. In that case centering on the construction process in hydropower project, safety evaluation indexes that construction couples with operation are established by introducing rough set theory, and then those indexes are simplified. Furthermore, the least evaluation index set and each coupled weight are determined in order to enable the evaluation method to have a feature of approximate function. Finally, the feasibility of this evaluation method is proved by empirical analysis. To sum up, this method is of theoretical and practical significance in safety evaluation for hydropower construction project.

Comprised of a broad range of diverse technologies, including information processing, communications, control, and electronics, Intelligent Transportation Systems (ITS) were first introduced as a means to solve the conflict between constantly increasing travel demand and insufficient transportation infrastructure. However, the impact of ITS on road safety was soon realized, and it became one of the major purposes of some ITS systems instead of only a side product. This paper summarizes the impacts of ITS technologies on road safety and the challenges of ITS safety evaluation. Based on the evaluation of collected ITS benefits information, this paper concludes that a variety of ITS technologies have the potential to make a substantial contribution to road safety and thereby have a substantial positive economic impact in the United States.

Objective The visual guiding system, as a tunnel traffic safety improvement method by using visual guiding facilities to actively guide driving safely, has been widely used in countries with many tunnels, in recent years. This paper aims to quantitatively study the comprehensive evaluation of traffic safety of the visual guiding system in tunnels, which has certain engineering application value and can provide support for the quantitative evaluation and optimal design of tunnel traffic safety. Methods Based on the analysis of the relevant factors of urban tunnel traffic safety, a multi-factor comprehensive evaluation system with 5 upper-level indicators and 12 basic-level indicators was proposed. Considering the independent and incompatible indicators, a comprehensive evaluation method of traffic safety of the visual guiding system in urban tunnels was constructed by using the extension matter-element model. Taking the scene of 4 types of tunnel curves, such as no facilities, horizontal stripe, chevron alignment sign, and LED arch, as examples, the comprehensive evaluation of various schemes were carried out by using simulation tests. Results The traffic safety comprehensive evaluation system of visual guiding system in urban tunnels can be analyzed from five aspects: perception reaction, guidance ability, driver factor, driving task, and facility appearance. The results demonstrated significant the comprehensive evaluation result of the target level of scene 1 was L4, scene 2 was L3, scene 3 was L2, and scene 4 was L1. That is, the final results of the comprehensive evaluation of the four scenes were poor, medium, good, and very good, respectively. Conclusions In the scheme of visual guiding system for urban tunnel curves, the effectiveness of the three types of designs, from high to low, was the LED arch, chevron alignment sign, and horizontal stripe, and the safety of the scene without facilities was the lowest. Hence, setting the LED arch in the urban tunnel curve has a good effect in the aspects of guidance ability, sight distance, and sight zone, and is conducive to the driver’s perception reaction and driving task.

Monitoring-data mechanism-driven dynamic evaluation method for slope safety