Heavy Vehicles Research Articles

Assessment of the surface water quality and primary health risk in urban wastewater and its receiving river Kathajodi, Cuttack of eastern India.

Kathajodi, the principal southern distributary of the Mahanadi River, is the vital source of irrigation and domestic water use for densely populated Cuttack city which receives anthropogenic wastes abundantly. This study assesses the contamination level and primary health status of urban wastewater, and its receiving river Kathajodi based on the physicochemical quality indices employing inductively coupled plasma mass spectroscopy and aligning with guidelines from the United States Environmental Protection Agency (USEPA) and WHO. The high WQI, HPI, and HEI in the catchment area (KJ2, KJ3, and KJ4) indicate poor water quality due to the influx of domestic waste through the primary drainage system and effluents of healthcare units. A high BOD (4.33-19.66mg L-1) in the catchment indicates high organic matter, animal waste, bacteriological contamination, and low DO, resulting in deterioration of water quality. CR values beyond limits (1.00E - 06 to 1.00E - 04) in three locations of catchment due to higher Cd, Pb, and As indicate significant carcinogenic risk, while high Mn, Cu, and Al content is responsible for several non-carcinogenic ailments and arsenic-induced physiological disorders. The elevated heavy metals Cd, Cu, Fe, Mn, Ni, and Zn, in Kathajodi, could be due to heavy coal combustion, vehicle exhaust, and industrial waste. On the other hand, Cu, Fe, K, and Al could be from agricultural practices, weathered rocks, and crustal materials. Positive significant (p ≤ 0.05) Pearson correlations between physicochemical parameters indicate their common anthropogenic origin and similar chemical characteristics. A strong correlation of PCA between elements and physiological parameters indicates their role in water quality deterioration. Assessing the surface water quality and heavy metal contents from this study will offer critical data to policymakers for monitoring and managing public health concerns.

Shape Optimization of Heavy Vehicles Chassis

The main objective of this project is to modify the design to decrease the deformation of chassis.

Development of a heavy vehicle torque rod applying continuous fiber reinforced thermoplastic composite materials instead of forged steel material: Design, analysis and optimization

The torque rod is an important component of the suspension system that connects the axle to the chassis in heavy commercial vehicles. The main motivation of this study is the development of a torque rod made of (1) plus cross-section, (2) continuous carbon and glass fiber reinforced hybrid thermoplastic composites, which can replace a forged steel torque rod used in heavy vehicles, has superior mechanical properties, provides minimum cost and weight. This study aims to develop a torque rod before its production within the framework of integration with Computer Aided Design (CAD), Finite Element Analysis (FEA), and Multi-Criteria Decision Making (MCDM). In this study, the design data and the properties of the composite materials were chosen as control factors. The minimum displacement, the best mechanical properties such as tensile stress, compressive stress, torsional shear stress, maximum critical buckling load, and the minimum part weight minimum production cost per piece were selected as quality characteristics. As a result of the FEA study, considering the experimental set of the Taguchi Method L25 orthogonal array, the data on mechanical properties, weight, and production cost per piece were subjected to the MCDM process using the Entropy Weighted TOPSIS method. As a result of the MCDM study, a torque rod made of continuous fiber-reinforced thermoplastic composite material, instead of a torque rod produced by forged steel, had the highest mechanical properties produced, the weight of the torque rod can be reduced by 64.76%, and the production costs per piece can be reduced by 37.5%. This study’s findings have shown that the torque rod produced from continuous fiber-reinforced thermoplastic composite materials in a new geometry with a plus cross-section can be substituted for the torque rod produced by steel forging. Thus, it will contribute to reducing the fixed vehicle weight, especially in heavy commercial vehicles, reducing CO2 emissions, and increasing the range of the vehicles.

Traffic noise measurement, mapping, and modeling using soft computing techniques for mid-sized smart Indian city

The present study presents an investigation into the utilization of artificial neural networks (ANN) and multiple linear regression model (MLR) for the prediction of traffic noise levels in various locations of Dhanbad city at varying intervals. Traffic noise indices measurements were carried out using sound pressure level meter (SLM). The prediction of equivalent A-weighted sound level (LAeq) and the sound level exceeding 10 percent of the time (L10) is carried out using various influencing factors such as number of cars, number of 2 wheelers, number of 3 wheelers, number of heavy vehicle, number of medium commercial vehicles, and traffic speed. The findings demonstrate the ANN model's proficiency in comparison of MLR model for providing precise prediction accuracy of traffic noise indices with a R2 of 0.94 for LAeq and 0.91 for L10. Furthermore, the frequency spectrum analysis reveals that high peaks were observed at lower frequencies ranging from 31.5 Hz to 50 Hz, middle frequencies from 500 to 800 Hz and higher frequencies from 3.5 kHz to 5 kHz. The noise maps at varying intervals revealed that most of the locations are having higher noise levels due to increase in vehicular movement. The study emphasizes on the potential significance of the proposed neural network-based prediction model in collaboration with noise mapping as a vital tool for the anticipation of traffic noise levels and the formulation of noise mitigation strategies in context of the mid-sized smart city like Dhanbad, India.

Improved Finite Element Model Updating of a Highway Viaduct Using Acceleration and Strain Data.

Most finite element model updating (FEMU) studies on bridges are acceleration-based due to their lower cost and ease of use compared to strain- or displacement-based methods, which entail costly experiments and traffic disruptions. This leads to a scarcity of comprehensive studies incorporating strain measurements. This study employed the strain- and acceleration-based FEMU analyses performed on a more than 50-year-old multi-span concrete highway viaduct. Mid-span strains under heavy vehicles were considered for the strain-based FEMU, and frequencies and mode shapes for the acceleration-based FEMU. The analyses were performed separately for up to three variables, representing Young's modulus adjustment factors for different groups of structural elements. FEMU studies considered residual minimisation and the error-domain model falsification (EDMF) methodology. The residual minimisation utilised four different single-objective optimisations focusing on strains, frequencies, and mode shapes. Strain- and frequency-based FEMU analyses resulted in an approximately 20% increase in the overall superstructure's design stiffness. This study shows the benefits of the intuitive EDMF over residual minimisation for FEMU, where information gained from the strain data, in addition to the acceleration data, manifests more sensible updated variables. EDMF finally resulted in a 25-50% overestimated design stiffness of internal main girders.

High-performance steering tracking control of open circuit variable-speed pump-controlled steering system for heavy-duty vehicles based on flow nonlinearity compensation

Heavy-duty vehicles with long bodies, a large number of axles and large loads are subject to increasingly high requirements for precise steering technology due to the increasing trend toward energy conservation and intelligent assisted driving as well as variable driving conditions. In this paper, an energy-efficient open circuit variable-speed pump-controlled steering system (OPCEHSSS) adapted for heavy loads is used, but its strong flow output nonlinearity and system nonlinear dynamic behavior greatly impede the steering performance. Therefore, in order to reduce the influence of the flow leakage of the fixed-displacement pump on the system and to ensure that the flow output of the system matches the control model, a mapping model based on the fitting of a two-layer neural network algorithm with a dynamic real-time compensation strategy (FNC) is proposed. In addition, considering the strong robustness of the system even under parameter uncertainty and unknown disturbance, a complex nonlinear mathematical model is established based on OPCEHSSS physical characteristics, and a dual-objective control strategy of steering angle and pressure based on sliding mode control (SMC) is proposed. However, in order to reduce the influence of high-order switching discontinuity on the steering and ensure the fast convergence of the control system, a fast super twisting algorithm (STA) based on double saturation function of the boundary layer is proposed. The experimental results show that the three different controllers can effectively reduce the steering angle error after the introduction of FNC. And in the case of a single axle loaded with 6 tons, the improved new FNC+STA integrated dual-objective control strategy improves the accuracy by 53.16% compared with PID and 40.67% compared with SMC. The steady-state error is maintained within 0.9°, realizing the high-performance steering tracking control of OPCEHSSS for heavy vehicles.

Coordinated control of yaw and roll stability in heavy vehicles considering dynamic safety requirements

In the field of heavy vehicle stability research, traditional safety requirements are often based on static scenario settings. However, the complexity and variability of actual road environments require safety control strategies that can be adapted to different driving conditions and environmental changes in real-time. To address this challenge, the paper proposes a coordinated control strategy for yaw and roll stability that considers the dynamic safety requirements. First, a quantitative analysis method for vehicle stability is proposed based on the dissipated energy theory, taking into account the lateral-vertical dynamics coupling characteristics. Additionally, a dynamic safety requirements identification model is developed by integrating the vehicle's future driving risk prediction algorithm. To meet dynamic safety requirements, a dynamic weight model predictive control method based on randomized ensembled double Q-learning reinforcement learning is designed. This method adjusts the control weights of yaw and roll stability online to flexibly address various destabilization risks, aiming to achieve more precise and efficient stability control. Through simulation and experimental verification, the results demonstrate that the proposed coordinated control strategy can effectively enhance the stability and safety of heavy vehicles in complex and dynamic driving environments.

Stabilization of Loose Soils as Part of Sustainable Development of Road Infrastructure

In the context of growing demand for road infrastructure expansion, sustainability is of key importance. Enhancing road construction technology ensures efficient, durable transportation infrastructure, vital for economic growth. Responsible road construction, especially in areas of historical and environmental significance, is essential. Preserving ecosystems and local heritage in road planning protects valuable areas and supports regional sustainability. Rural roads, often in forested areas, should maintain natural aesthetics. Economic challenges require flexible, efficient roads. Many existing unpaved roads, especially in rural and forest environments, fail to meet increasing traffic and load of heavy agricultural and maintenance vehicles. Soil stabilization methods, discussed in various publications, offer sustainable solutions. Research on ecofriendly binding additives provides the opportunity to reduce cement consumption and CO2 emissions. Such innovations enhance road efficiency, reduce maintenance costs, and benefit the environment. Investing in modern road technologies mitigates climate change effects by reducing emissions and protecting ecosystems. Our research indicates that soil stabilization technologies significantly improve road strength and durability. Additives can increase compressive strength by over 50% with minimal cement content. Continued research into road quality and durability is vital for sustainable transport infrastructure development. The results presented in this paper were obtained after two periods of solidification: after 7 and 30 days, with three types of ads (ion-exchangeable, chemical, and polymeric) to cement. In all tests, compaction strength improved by at least 35% in samples with the lowest cement content.

Evaluation of mechanical properties of paver blocks by replacing cement with fly ash and marble waste

Paver blocks (PB) play a pivotal role in various construction and infrastructure works providing aesthetically and durable pleasing surfaces for various applications such as pavements, walkways, and driveways. These blocks can be used for heavy vehicle loads instead of low-strength clay bricks and tiles. PB gained focus in the construction industry due to its multi-advantages like high strength, durability, and low maintenance cost. However, due to the usage of cement, its application is limited, which releases a huge amount of carbon dioxide into the ecosystem. Thus, it leads to global warming and climate change. In addition, cement is one of the expensive materials used in PB, which further reduces the interest of the construction industry and end-users of PB. Marble waste as its excessive amount of generation from stones in industry and fly ash as a byproduct from coal combustion immediate opportunities to use these materials and reduce the impact of waste material on the environment. Therefore, this study aims to reduce cement consumption by partially replacing marble waste and fly ash combinedly. The study contributes practically to the use of alternative materials in the construction industry. Three types of samples namely M1 (replacement with marble waste), M2 (replacement with fly ash), and M3 (replacement with both fly ash and marble waste) were used. Various proportions were added as a partial replacement, the replacement varying from 5 to 30%, which was 5%, 10%, 15%, 20%, 25%, and 30%. Statistical analyses were carried out for interpretations of the data. The result concluded that all three mixes achieved their maximum compressive strength on different days of curing. M1-15 and M3-20 mixes achieved maximum compressive strength related to control specimens at 56 days. However, the M2-20 mix achieved maximum compressive strength at 7, 28, and 56 days, The maximum flexural strength was recorded by the M1–15 mix at 7 and 56 days, while the M2–20 and M3–20 mix achieved maximum flexural strength at 7, 28 and 56 days. ANOVA tests by one-way indicate that there is no difference in the mean of compressive strength however, there is a difference in the mean of flexural strength. The Tukey post hoc analysis shows a statistically significant difference between all levels of days of compressive and flexural strength, except for some levels of compressive strength. The correlation test results indicate a positive and strong association between all three mixes.

Applicability of an Ionising Radiation Measuring System for Real-Time Effective-Dose-Optimised Route Finding Solution during Nuclear Accidents

The reduction in the effective dose of evacuated injured persons through contaminated areas of nuclear accidents is an essential emergency services requirement. In this context, there appeared a need to develop a dose-optimised route finding method for firefighting rescue vehicles, which includes the development of a real-time decision support measurement and evaluation system. This determines and visualises the radiation exposure of possible routes in a tested area. The system inside and outside of the vehicle measures the ambient dose equivalent rate, the gamma spectra, and also the airborne radioactive aerosol and iodine levels. The method uses gamma radiation measuring NaI(Tl) scintillation detectors mounted on the outside of the vehicle, to determine the dose rate inside the vehicle using the previously recorded attenuation conversation function, while continuously collecting the air through a filter and using an alpha, beta, and gamma radiation measuring NaI(Tl)+ PVT + ZnS(Ag) scintillator to determine the activity concentration in the air, using these measured values to determine the effective dose for all routes and all kinds of vehicles. The energy-dependent shielding effect of the vehicle, the filtering efficiency of the collective protection equipment, and the vehicle’s speed and travel time were taken into account. The results were validated by using gamma point sources with different activity and energy levels. The measurement results under real conditions and available real accident data used in our simulations for three different vehicles and pedestrians proved the applicability of the system. During a nuclear accident based on our model calculations, the inhalation of radioactive aerosols causes a dose almost an order of magnitude higher than the external gamma radiation caused by the fallout contamination. The selection of the appropriate vehicle and its route is determined by the spectrum that can be measured at the accident site but especially by the radioactive aerosol concentration in the air that can be measured in the area. In the case of radiation measuring detectors, the shielding effect of the carrier vehicle must be taken into account, especially in the case of heavy shielding vehicles. The method provides an excellent opportunity to reduce the damage to the health of accident victims and first responders during rescue operations.

Pattern and distribution of injuries associated with road traffic accident in Haldwani (Nainital) - An autopsy based study

Indiais one of the fastest growing economies. There is a rapid inflation of vehicles on the road that range from motorcycles to heavy vehicles which also shows an active surge in the fatal road accidents. This study is focussed to find out the pattern and distribution of injuries in fatal road traffic accident cases in Kumaon region of Uttarakhand as to plan at the time of policy making and traffic law implementation.: The present study was conducted in the department of Forensic Medicine & Toxicology of Government Medical College, Haldwani from January 1 2019 to December 31 2019, on total 110 cases of RTA brought to mortuary for medico-legal post mortem examination.: Maximum number of cases sustained head and neck injuries (42 out of 110 externally) followed by extremities injury (28 out of 110). Total 38 cases out of 110 sustained head and neck injuries internally, followed by abdominal injuries (28 cases). Abrasions (30 cases) and laceration (29 cases) were commonest type of external injury noted in RTA cases followed by contusion (22 cases) and fracture (19 cases). Most common cause of death among RTA victims was head injury (40 out of 110 cases) followed by shock and haemorrhage (37 out of 110 cases).

Exploring the Feasibility of Kuiper Belt Missions Supported by Centrifugal Nuclear Thermal Propulsion

Missions to the Kuiper belt have previously been carried out only as flybys and with very small payloads. Investigating launch windows for Kuiper belt missions supported by centrifugal nuclear thermal propulsion (CNTP) contributes to defining its operational use case. Results indicate that CNTP enables rendezvous missions to the Kuiper belt, both with direct transfer trajectories or planetary gravity assist trajectories, although there are many challenges to making these mission architectures feasible. The direct trajectories have transfer times of roughly 14 to 16 years while combining CNTP with gravity assists from Jupiter could lower transfer time to as low as 10 to 12 years to Kuiper belt objects such as Pluto and Quaoar. These missions are then shown to inform the architecture of the CNTP injection stage vehicle, which can be supported by heavy and super-heavy commercial launch vehicles with a single launch. Last, drawbacks of the mission and vehicle architectures are given that impose limits on the use case for CNTP on these missions.

Temporal evolution of traffic accident mortality rates in the State of São Paulo, Brazil, in the period 2009-2019

Introduction: external causes are considered a public health problem in the world, associated with socioeconomic, political, and cultural diversities. Among them, traffic accidents stand out.
 Objective: to assess the trend in traffic accident mortality for each sex in the state of São Paulo, Brazil.
 Methods: ecological study of time series analyses. Secondary data referring to deaths from traffic accidents by place of residence in the state of São Paulo, Brazil, in the period 2009 - 2019 were used.
 Results: the total mortality rate in 2019 for females is 39.80 and for males, 185.85, with a reduction of 4.96% per year for both sexes. The trends in mortality from traffic accidents for females proved to be stationary for motorcyclists, motorized tricycle, pickup truck, heavy transport vehicle, and bus occupants at the end of the study period. For males, the same pattern was observed, but only for truck, heavy transport vehicle, and bus occupants. In the rest of the vehicles, the mortality rate showed decreasing trends.
 Conclusion: the highest number of deaths occurred among males (81.38%), aged between 20 and 49 years (58.70%), single (49.12%), on public roads (46.73%) and hospitals (45.64%). Females have more stationary trends than males.

Methodology to Counter Heterogeneity at Urban Multilane Roundabouts

Despite the adoption of roundabouts in developing countries for traffic management and smooth flow, the concept of traffic heterogeneity management at these intersections is relatively unexplored. Estimating passenger car units (PCUs) for different vehicle types to homogenize traffic is a recognized approach worldwide. In this study, vehicles were classified into five categories to provide a meaningful context for the analysis. The study proposes a model to estimate PCU values for different vehicle types, specifically at roundabouts, after identifying the potential influencing factors. The study was based on data collected from 10 roundabouts in three Indian cities, having different physical and geometrical characteristics. The proposed method yielded PCU values that were partially comparable with existing standards. Comparisons with the Indian Highway Capacity Manual (Indo-HCM) revealed that this publication underestimated PCU values for two-wheelers and three-wheelers by 20% and 11% respectively, but overestimated PCU values for big cars and heavy vehicles by 9% and 12%, respectively. Method appropriateness was ascertained from the lack of prior assumptions made about traffic and geometrical characteristics. To prevent unnecessary re-estimation of PCU values across locations, the idea of a heterogeneity counter component (HCC) was proposed. The model was trained using cross validation on a dataset of seven roundabouts, and its performance was evaluated on a separate dataset using mean absolute percentage error. The relationship between PCUs and the geometrical features of roundabouts, and the effect of traffic characteristics on HCC were studied. The findings might be considered while revising relevant codes and manuals (e.g., IRC-65:2017, Indo-HCM).

The effectiveness of different wear indicators in quantifying wear on railway wheels of freight wagons

AbstractRailway infrastructure relies on the dynamic interaction between wheels and rails; thus, assessing wheel wear is a critical aspect of maintenance and safety. This paper focuses on the wheel–rail wear indicator T-gamma (Tγ). Amidst its use, it becomes apparent that Tγ, while valuable, fails to provide a comprehensive reflection of the actual material removal and actual contact format, which means that using only Tγ as a target for optimization of profiles is not ideal. In this work, three different freight wagons are evaluated: a meter-gauge and a broad-gauge heavy haul vehicles from South American railways, and a standard-gauge freight vehicle operated in Europe, with different axle loads and dissimilar new wheel/rail profiles. These vehicles are subjected to comprehensive multibody simulations on various tracks. The simulations aimed to elucidate the intricate relationship between different wear indicators: Tγ, wear index, material removal, and maximum wear depth, under diverse curves, non-compensated lateral accelerations (Anc), and speeds. Some findings showed a correlation of 0.96 between Tγ and wear depth and 0.82 between wear index and material removed for the outer wheel. From the results, the Tγ is better than the wear index to be used when analyzing wear depth while the wear index is more suited to foresee the material lost. The results also show the low influence of Anc on wear index and Tγ. By considering these factors together, the study aims to improve the understanding of wheel–rail wear by selecting the best wear analysis approaches based on the effectiveness of each parameter.

Analysis of the extent of heavy vehicle overloading on Namibian trunk roads and evaluation of the effectiveness of existing mitigation measures

Overloading of heavy vehicles reduces pavement life and increases pavement life cycle costs. As part of Namibia's strategy to control heavy vehicle overloading on the road network, weighbridge facilities have been constructed at strategic locations on primary routes (trunk roads). The study analysed the extent of heavy vehicle overloading on Namibian trunk roads, as well as the effectiveness of existing overloading mitigation measures. The dataset comprised heavy vehicle loading information from the year 2015 to 2019, from ten static weighbridge facilities. The parameters investigated include overloading magnitude, the effect of overloading on road pavement life, and the effectiveness of current overload mitigation measures. The results showed that 13.3% of the vehicles weighed were overloaded, with a compounded decrease in overloading of approximately 0.5% per annum. Despite the overloading decrease, the study found that the estimated road service life was reduced by as much as nine years over the study period. High levels of weighbridge avoidance and poor stakeholder coordination in mitigating overloading were identified. The study recommends deploying high-speed weigh-in-motion systems, an increase in fines charged for overloading offenses, and developing a demerit point-based system for habitual offenders to strengthen mitigation measures.

Influence of inflow conditions on simplified heavy vehicle wake

In the current study, the impact of various inflow conditions, including turbulent wind profiles and turbulent intensity, on the wake flow topology of a simplified ground transportation system (GTS) model was investigated using the improved delayed detached eddy simulation. The reliability and accuracy of the numerical method adopted in this paper were verified against the results comprising the aerodynamic drag and the wake flow structure of the GTS model obtained from the large eddy simulation and the experimental data. The research results indicate that turbulent winds characterized by logarithmic and uniform velocity profiles resulted in significantly different wake flow topologies yet exhibit the same dominant frequency. The turbulent intensity also plays a crucial role in the wake of the GTS model. It is observed that an increase in turbulence intensity corresponds with a rise in the aerodynamic drag. Specifically, when the turbulence intensity is set at 15%, there is a 3.68% increase in the aerodynamic drag of the GTS model compared to a case where the turbulence intensity was only 5%. In addition, the turbulent intensity is critical to the dominant frequency characteristics of the wake region of the GTS model. These results demonstrate that both the velocity profiles and the turbulence intensities significantly influence the wake flow topology and aerodynamic drag of the GTS model, providing a valuable reference for establishing appropriate inflow conditions and exploring the formation mechanism of flow topology in the wake of the GTS model.

Nanostructured Solid/Liquid Acid Catalysts for Glycerol Esterification: The Key to Convert Liability into Assets.

Owing to the growing concerns about the dwindling fossil fuel reserves, increasing energy demand, and climate emergency, it is imperative to develop and deploy sustainable energy technologies to ensure future energy supply and to transition to the net-zero world. In this context, there is great potential in the biorefinery concept for supplying drop in biofuels in the form of biodiesel. Biodiesel as a fuel can certainly bridge the gap where electrification or the use of hydrogen is not feasible, for instance, in heavy vehicles and in the farm and marine transportation sectors. However, the biodiesel industry also generates a large amount of crude glycerol as the by-product. Due to the presence of several impurities, crude glycerol may not be a suitable feedstock for all high-value products derived from glycerol, but it fits well with glycerol esterification for producing glycerol acetins, which have numerous applications. This review critically looks at the processes using nanostructured solid/liquid acid catalysts for glycerol esterification, including the economic viability of the scale-up. The homogeneous catalysts reviewed herein include mineral acids and Brønsted acidic ionic liquids, such as SO3H-functionalized and heteropoly acid based ionic liquids. The heterogeneous catalysts reviewed herein include solid acid catalysts such as metal oxides, ion-exchange resins, zeolites, and supported heteropoly acid-based catalysts. Furthermore, the techno-economic analysis studies have shown the process to be highly profitable, confirming the viability of glycerol esterification as a potential tool for economic value addition to the biorefinery industry.

A MICRO-COOLED HIGH-STRENGTH WELD FOR HEAVY TRANSPORT MEANS

This paper focuses on the technical problem of repairing the main operating elements of heavy vehicles (semitrailers, dumps, and drums). If these vehicles are in service, significant changes in work schedules can occur, and costs can be generated immediately. Therefore, using the correct technology for repairs is crucial to minimizing financial and logistic difficulties. The article aims to analyze the mechanical properties of an MMA (Manual Metal Arc) welding (covered electrodes) joint made of Hardox 450 steel. This kind of material has a martensitic microstructure, which is difficult to weld because of changes in the components to the other ones during the joint process. Other inconveniences are related to the different chemical composition of steel and covered electrodes, their mechanical resistance, and thermodynamic conditions (consisting of the pre-heating temperature and the cross-pass temperature). Therefore, the joint quality should be determined using a few methods. In this case, NDT (magnetic and radiographic tests) and DT (microstructural analysis and static as well as fatigue tests) were used. All obtained results have enabled the proposed guides for the MMA welding of the steel grade. This is indicated as follows: (1) the method of bevelling the sheets before welding should be used, (2) pre-heating is necessary at temperature levels of 100 C and 125 C, and (3) the recommended interstitial temperature is between 170 C and 200°C.

Assessing the collision risk of mixed lane-changing traffic in the urban inter-tunnel weaving section using extreme value theory

Urban inter-tunnel weaving (UIW) sections are characterized by short lengths and frequent lane-changing behaviors in the area, commonly used for fast through traffic. These features increase the likelihood of collisions, however, collision risk assessment in this area has been inadequate. The aim of this study was to evaluate the potential collision risk of urban inter-tunnel weaving (UIW) sections in mixed lane-changing traffic conditions in morning rush hours, utilizing surrogate safety measures. The investigation involved the collection of trajectory data via an unmanned aerial vehicle (UAV). Time to collision (TTC) and extended time to collision (ETTC) were chosen as surrogate safety indicators. The estimation of collision risk was conducted using Extreme Value Theory (EVT) by means ofsurrogate safety indicators. It was found that the threshold of TTC and ETTC in this area was 1.25 s. Furthermore, a comprehensive evaluation of collision risks associated with various vehicle types was performed, revealing an inverse relationship between thecollisions riskof vehicles in mixed traffic and their size. It was worth noting that while heavy vehicles exhibit a lower collision risk, they resulted in the highest energy loss and inflicted greater harm in the event of a collision. By an examination of the distribution features pertaining to conflict types during the operation of heavy vehicles, it showed that the highest likelihood of conflict with heavy vehicles occurred when adjacent lanes are involved. Consequently, the implementation of assisted driving technology for heavy vehicles was imperative in order to mitigate the risk associated with side collisions.