Road Tunnel Safety Research Articles

Improving Traffic Safety in Existing and New Road Tunnels with the Novel NDBA Concrete Safety Barrier

Abstract Two main elements are essential in terms of road traffic safety. The first element is accident prevention and the second is the minimization of accident severity once a crash has occurred. Concrete safety barriers have very good anti-collision performance against roadside obstacles, relatively modest construction and maintenance costs, and low dynamic deflection and therefore are widely used in tunnels. Thanks to their characteristic redirective profile these barriers can redirect errant vehicles into their original lane after collisions. However insufficient research has been done for increasing the performance of concrete barriers purposely designed for tunnel installations. This research presents the new “NDBA Tunnel” concrete safety barrier designed and constructed by the Italian Road Operator ANAS indicated to be installed in road tunnel sections for safety improvements. In Europe, road safety barriers must be designed in compliance with the European Standard EN 1317. Therefore, the barrier “NDBA Tunnel” was subject to the TB11 and TB81 full-scale crash tests according to the European EN 1317 regulation. The results prove the barrier's ability to absorb impact loads of light and heavy vehicles with a working width W2. Therefore, the NDBA concrete barrier can be installed on existing or new tunnels at a distance less than or equal to 70 cm from the facing of the tunnel wall.

A Theoretical Study on the Resilience Evaluation Method of Operational Road Tunnel Systems

Road tunnel operation will suffer from a lot of uncertain external disturbances, which will greatly affect the operational safety of road tunnels and even block traffic. Focusing on road tunnel operation safety and disaster-resistant ability, the concept of resilience is introduced to provide a scientific and effective basis for road tunnel operation and emergency management. In this paper, the concept of tunnel system resilience was proposed based on the concept of system resilience. A theoretical analysis model of road tunnel resilience was built to describe the change in road tunnel system function over time due to external disturbances (e.g., fires, traffic accidents, floods, earthquakes). Five fundamental attributes of road tunnel system resilience were proposed to describe the resilience level. A resilience evaluation method for road tunnels was proposed based on the functional network. The vulnerable links of road tunnels subjected to external disturbances can be analyzed using this method. This study will provide important references for the resilience evaluation method of road tunnels and risk mitigation strategies.

Variables Affecting the Risk of Vehicle Collisions in Australian Road Tunnels

The characteristics of road tunnels as part of the road network differ from those of general open roads, resulting in different vehicle collision characteristics. Understanding the characteristics of these collisions and the variables that contribute to them is critical for developing mitigation strategies. The purpose of this paper is to identify the characteristics of vehicle collisions in Australian road tunnels, as well as to investigate the variables that influence the number of casualties and the types of collisions. The study utilised data from seven road tunnels in Queensland and New South Wales. Data cleaning and transformation were carried out, yielding 12 variables for further analysis with statistical descriptive analysis, cross-tabulation, and logistic regression. The findings reveal that rear-end collisions are the most common type of collision in Australian road tunnels. Furthermore, only one variable had a significant impact on the number of casualties, while three variables had a significant impact on the types of collisions. These findings provide valuable insights for tunnel stakeholders in developing preventive measures to improve road tunnel safety.

Traffic safety assessment and prediction under different lighting service states in road tunnels

The lighting service state of road tunnels has an important impact on traffic safety. To assess and predict traffic safety in road tunnels under different lighting service states, a traffic safety assessment system of road tunnels was innovatively established by using visual recognition clarity data from 300 field experiments, which uses the proposed traffic safety factor to assess the traffic safety of road tunnels under different lighting service states. Then, the Particle Swarm Optimization (PSO) algorithm is used to optimize the Back Propagation (BP) neural network, and a new traffic safety intelligent prediction method in road tunnels was constructed to predict the traffic safety factor under different lighting service states. The results of the study show that there is a negative correlation between simulated vehicle speed and visual clarity and a positive correlation between lighting attenuation and visual clarity. There is a negative correlation between the number of luminaire failures and the visual recognition clarity. When the lighting attenuation is below 70% or four and above luminaires fail, the lighting service states of road tunnels can seriously threaten traffic safety. The PSO-BP neural network model can accurately predict the traffic safety factor. The critical value of the traffic safety factor is 0.5965. This means that the lighting service state poses a threat to traffic safety in road tunnels when the traffic safety factor is lower than this value. The results of the study can provide the basis for developing a safe and low-carbon tunnel lighting maintenance program.

Validation of a Driving Simulator for Road Tunnel Behavioural Studies

Introduction. According to European regulations, road tunnel safety is strategic in the management of national and international road corridors. Although the accident rate is lower in tunnels than on open roads, the severity of crashes in tunnels is higher due to the presence of hard lateral obstacles and limited space in case of lane departure. Driving simulation studies can support design decisions to assess the impact of any safety improvement albeit driving simulators must be validated to understand how the experimental results relate to real driving conditions. Method. This study deals with the behavioural validation of the fixed base driving simulator of the RSDS Lab for safety studies for tunnels. Field speed and lateral position data for vehicles were collected by image analysis of video sequences collected from the CCTV cameras in five sections of the Fréjus tunnel (Italy-France). The tunnel was faithfully modelled in the virtual scenario, and the same data were collected by extracting records at the same cameras’ stations. Thirty-five participants were involved in a between-subject experiment. Fifteen drivers with Italian B licenses drove a car, and twenty professional drivers with Italian C and/or D licenses drove a heavy truck. Results and Conclusions. Normality tests for data distributions and t-tests for the comparison between real and simulated data were conducted. The simulator achieved the relative validation for truck speeds (with values observed in the simulation always lower than those observed in real driving), and absolute validation with regard to truck lateral position. Opposite outcomes were obtained for cars, with absolute validity for speed and relative validity for lateral position. The relative-absolute validation of the driving simulator enables us to establish how experimental outcomes can be generalized to understand the impact of any safety countermeasure.

Analysis of Important Factors Having an Impact on Safety in Road Tunnels – Research Findings

Aim: This article presents relevant safety issues in road tunnels based on the results of a survey and evacuation experiments conducted on real scale in two existing road tunnels in Poland. Project and methods: An analysis of the relevant factors influencing the level of safety in road tunnels was carried out based on the results of experi - mental studies in two road tunnels in which the course of evacuation under fire conditions was observed. As part of the study, several evacuation trials were carried out at equal smoke levels, examining a different parameter each time: pre-movement time, speed of movement, the effect of smoke on the speed of movement, the effect of tunnel infrastructure on evacuation, among others. A survey carried out among 504 respondents, in turn, attempted to assess the awareness of hazards and safety procedures in road tunnels. The survey has four parts and questions covered the following issues: knowl - edge of tunnel infrastructure, behaviour in case of congestion, choice of evacuation route, behaviour during the evacuation, personal belongings during the evacuation, self-assessment of tunnel safety knowledge and the role of experience. An analysis was also carried out of the information available in Poland on safety guidelines for road tunnels, which can help tunnel users to improve their knowledge on tunnel safety. Results: The survey results indicate an insufficient level of knowledge regarding safety in road tunnels – only 16% of respondents answered more than 50% of the questions correctly. Ignorance of road tunnel infrastructure itself and the safety rules for the tunnel was also diagnosed. An analysis of the information available to the road users demonstrates that this information is difficult to access and that there is a lack of uniform guidelines to educate the public on the topic raised in the article. A significant impact of evacuation exercises carried out on an accurate scale was emphasised, providing valuable data on the evacuation process and increasing the level of safety in the engineering facilities analysed by raising the awareness of the partici - pants in the experiment. Conclusions: The research findings presented in this article allow for better understanding of the behaviour of the participants of accidents and fires in road tunnels. In addition, the need to raise the awareness of the road users on the dangerous situations that may occur in a tunnel and the appropriate response to them has been demonstrated. Keywords: safety, fire, smoke, evacuation, road tunnel Type of article: original science article

Study on influence of breathing zone combined with underfloor makeup air supplement on smoke exhaust of road tunnel fire

In the era of rapid economic development, tunnel construction projects are increasing year by year in China, continuously expanding the urban network In the era of rapid economic development, tunnel construction projects are increasing year by year in China, continuously expanding the urban network radiation area, and accelerating the progress of the national modernization project. The subsequent tunnel traffic fire accidents are also increasing When a tunnel fire occurs, how to effectively supply makeup air to prevent the fire smoke from spreading to the evacuation passage of the When a tunnel fire occurs, how to effectively supply makeup air to prevent the fire smoke from spreading to the evacuation passage of the tunnel and exhaust the smoke as soon as possible has become a key concern in the field of tunnel disaster prevention. The layout of the smoke exhaust outlets under the mode of breathing zone combined with underfloor makeup air supplement was mainly used to study the problem of smoke exhaust in tunnel fires. The results show that under the same smoke exhaust flow rate, with the increase in the area of the results show that under the same smoke exhaust flow rate, with the increase in the area of the smoke outlet, the smoke exhaust efficiency of each exhaust outlet increases, and the total efficiency also increases. The width of the exhaust outlet has a significant effect on the smoke exhaust efficiency. However, the length of the exhaust vent has little effect on the efficiency of smoke exhaust. Under the mode of breathing zone combined with underfloor makeup air supplement, arranging smoke outlet with a size of 2 m×1.5 m every 10 m has a better smoke extraction effect, and the total smoke exhaust efficiency can reach 75.77%. Fire safety of road tunnels has always been the focus of social concern. The makeup air supplement and smoke exhaust mode proposed in this study is expected the makeup air supplement and smoke exhaust mode proposed in this study is expected to provide a theoretical basis for the design of tunnel smoke prevention and exhaust systems.

Численное моделирование пожара в автодорожном тоннеле. Выбор расчетной сетки

Рассматривается вопрос выбора расчетной сетки при моделировании пожара в тоннеле с помощью полевого метода и проводится оценка возможного влияния размеров ячеек сетки, а также граничного условия постоянства давления на результаты расчета. Выполнено моделирование пожара для четырех размеров расчетной сетки. Обоснована возможность применения наиболее грубой из используемых сеток с точки зрения инженерных расчетов, в том числе с оговоркой относительно постановки граничного условия. The issue of fire safety of road tunnels is currently an urgent task. Road tunnels are usually not standard typical facilities, but the unique structures. Therefore, it is necessary to study the influence of various parameters on the development of fire in order to take into account the characteristics of a particular object and make decisions on its effective fire protection. Implementation of field tests in this case is expensive and time-consuming. In this regard, numerical modeling is one of the most effective methods of such research. Field models are the most common and currently used for numerical calculations. These models are based on the numerical solution of the system of conservation equations for small control volumes of the calculation grid. This paper examines the issues of selection the calculation grid when modeling a fire in tunnels using the field method is considered and the possible influence of the size of the grid cells is estimated. The mathematical model used in this work is based on a set of differential equations of hydrodynamics, heat transfer, as well as the equation of conservation of the masses of components. Four computational grids were selected for a horizontal (without slope) model tunnel to determine the optimal cell size. As a result of conducted calculations it was established the following: the size of calculated grid is not fundamental for the initial stage of the fire; the use of smaller grid may be preferable at further development of fire, accompanied by increase of combustion capacity to the maximum; the maximum temperature values, especially in the far sections, are obtained on the coarsest grid. The use of such a grid for estimated engineering calculations can be allowed.

What Is the Knowledge of Evacuation Procedures in Road Tunnels? Survey Results of Users in Poland

This paper presents a preliminary assessment of road tunnel safety issues among respondents—specifically, real and potential users of road tunnels. We recruited a group of respondents to study their knowledge of evacuation procedures and awareness of safety issues in road tunnels. We conducted surveys with 504 participants, 12.7% of whom had previously participated in real-scale evacuation experiments in a road tunnel. Analysis of respondents’ answers reveals that their knowledge of safety procedures is unfortunately not sufficient. On average, the respondents selected the most recommended answer for approximately 5.35 out of 15 questions. Only 16% of respondents correctly answered more than 50% of the survey questions; moreover, no respondent provided the correct answers for 12 or more questions. Interestingly, most respondents were convinced that they had a better knowledge of road tunnel safety issues than was actually the case. The results of the survey demonstrate a significant educational role of evacuation exercises. Individuals who have participated in an evacuation have better knowledge, allowing them to apply the correct rules of road tunnel safety procedures. Various aspects addressed in this paper can be taken into consideration in an information campaign regarding safety in road tunnels during a fire.

Final smoke spread simulations for Tunnel traffic & operation simulator

Road and highwaz tunnels have become an essential part and an important element of the road network. In terms of general transportation and transit of goods they have also transnational significance. Tunnels located on the trans-European road network with a length of more than 500 m must also comply with the requirements of European Directive 2004/54/EC. That directive imposes an obligation on investors and management organizations to pay particular attention to the fire safety of tunnels. This paper describes final smoke spread simulations of road tunnel fires which were created as outputs of the project entitled “Models of formation and spread of fire to increase safety of road tunnels”.

Inherent fire safety engineering in complex road tunnels – Learning between industries in safety management

Road tunnels in Norway are becoming increasingly complex, and several long subsea tunnels are either under construction or planned for the near future. The Office of the Auditor General in Norway recently stated that there is a need to improve fire safety in road tunnels. By systematically examining safety management in an industry dealing with high risks on a daily basis and combining this with knowledge gained through investigations of tunnel fire accidents and existing research on tunnel fires, this paper aims to identify some areas for improvement in the fire safety engineering of complex road tunnels. The ‘inherently safer’ philosophy is used as a starting point for safety management, and there appears to be some potential for improvement within tunnel fire safety engineering, when taking into account parameters and uncertainties regarding fire growth, heat release rates, smoke stratification toxicity, and time available to escape with different ventilation strategies.

Development of a risk-based method for predicting the severity of potential fire accidents in road tunnels based on real-time data

Fire incidents are considered serious events for road tunnel safety because they can evolve into catastrophic accidents. Bearing in mind that tunnels constitute critical infrastructure elements of road systems, risk assessment has been employed to prepare tunnels to deal with such incidents. However, if an incident occurs, an adequate response is also related to the information about the particular event. To this respect, a novel risk-based method is proposed to support tunnel operators in assessing the criticality of potential fire incidents by using real-time data. The structure of the proposed method is as follows. Initially, the backlayering that determines the criticality of an incident is examined and the stochastic parameters of the system that affect backlayering are identified. Subsequently, multiple simulations are performed by changing the examined parameters randomly and thus the relation between backlayering and those parameters arises. As a result, the developed relation provided with real-time data can estimate the potential severity of any incident occurring in real time. The outcome facilitates tunnel operators to predict promptly the potential severity of fires and make better-informed decisions. This will allow a more efficient operation of the control room of the tunnel. An illustrative case is presented to showcase the utilisation of the proposed method.

International Conference on Road Tunnel Safety and Risk Prevention and Control (ICRTSR 2019)

Preface The tunnel is an important transportation infrastructure. By the year of 2018, there were 17738 highway tunnels in China, 17236.1 kilometers long, thousands of urban tunnels and tens of thousands of railway tunnels. The tunnel is affected by the surrounding buildings, the crowded vehicles, the complex operation environment, the increase of bad disaster and the insufficient management level, which make the safety of operation and maintenance of the tunnel prominent and sensitive to the social impact. Therefore, it is particularly urgent and important to improve its operation and maintenance safety level. In the past few years, China, like other countries in the world, has seen a lot of accidents in tunnel operation and maintenance. At the same time, a lot of new technology for tunnel operation and maintenance has been put forward. This conference will provide a platform for scholars and tunnel managers all over the world to share the latest research results and management methods, and work together to improve the safety level of tunnel operation and maintenance.The Organizing Committee of ICRTSR 2019 is pleased to announce that the International Conference on Road Tunnel Safety and Risk Prevention and Control (ICRTSR 2019) has been held in Chongqing, China during December 05-07, 2019.All papers submitted at the conference have been through rigorous review and process by the conference committee, and a volume of high-quality papers were selected for oral presentation and publication at the conference. We hope these books will serve as a reference for readers.We would like to thank the conference committee for reviewing the papers impartially and responsibly. We also want to thank everyone and related institutions for their support and help. We sincerely hope the 2019 International Conference on Road Tunnel Safety and Risk Prevention and Control (ICRTSR 2019) will become a top conference, and we are convinced that the proceedings of this conference will be an important study reference and knowledge source, which can not only promote the progress of science and engineering, but also boost the development of other new products and processes.The Organizing Committee of ICRTSR 2019List of Committee member, Scientific Committee, Chairman, Vice chairman, Committeeman, Organizing Committee, Chairman, Vice chairman, Member are available in this pdf.

Geometric Design Issues and Safety Analysis of Two-way Rural Road Tunnels

Rural road tunnels may pose specific issues from several perspectives: mainly environmental, geotechnical/structural (excavation methods), economical. Geometric road design is then an often arduous task, which should be conducted by trying to make trade-offs between the different issues, and at the same time, it should be compliant to relevant standards and regulations. Nevertheless, the safety of road tunnels should be preserved, not only considering technological systems (e.g. ventilation systems, emergency exits and paths), but also regarding traditional road-safety issues related to road geometric features. In fact, the analysis of recent accident data related to two-way two-lane rural road tunnels has revealed that accident frequencies/rates in two-way two-lane rural road tunnels are comparable with those on the corresponding open sections, even with some differences concerning the accident types. Since road safety issues may be exacerbated by geometric design inaccuracies, some relevant road tunnel geometric issues are discussed in this study. These issues, scarcely treated in previous research and not addressed in detail in technical documents, emerge from the match between different design needs. In detail, those relate to: 1) the possible need for variable road tunnel cross-sections in case of lane/shoulder widenings for the sake of improving visibility or for other reasons, or in case of lay-bys, 2) the possible need for climbing/overtaking lanes in case of steep downhill or uphill slopes. An attempt at addressing the mentioned problems is provided, based on relevant existing research and technical documents. In particular, the preliminary design stages leading to a “WES” (Without Enlargement Solution) solution are described. Hence, besides enlarging the research body in this specific field, the study is also potentially deemed useful for practitioners who have to face similar design problems.

Safety in Road Tunnels – Safety Target Proposal

The purpose of this paper is to propose a quantitative target for assessment of life safety in road tunnels and describe how such a target can be utilized and developed further. The target is developed from an analysis of initiating events, accident statistics and analytical approaches and it makes it possible to tailor the safety concept in individual tunnels to meet the target by means of quantitative risk analyses. The results indicate that the practice proposed is beneficial for both quality and transparency in the decision-making, as well as it can be judged to have the potential to improve cost-efficiency in the safety related work. It is concluded that the target should be calibrated and evaluated with data from real tunnels before implementation and that the resulting safety level from present ruling is assessed. Also, it is concluded that the total cost to realize the safety target is assessed. It is recommended to put more effort on general accident prevention in tunnels compared to surface roads in order to reduce the number of events that may escalate beyond control. It is also recommended that the road tunnel safety learning processes are improved by routine collection, compilation and evaluation of data on road tunnel accidents as well as vehicle-fires and dangerous goods accidents in road traffic as a whole.

CFD-based fire spread visualization for improvement of road tunnel safety

Teaching and training of operators of road and highway tunnels are necessary to increase their preparedness for incidents accompanied by fire and ensure safe tunnel operation. For such purposes Tunnel Traffic & Operation Simulator (TTOS) is used in Slovakia. TTOS is capable to simulate various types of emergency situations in 1 km long twin tube virtual highway tunnel with longitudinal ventilation including scenarios of car accidents accompanied by fire. However, TTOS does not provide information about the fire dynamics and smoke stratification. In this paper, the use of the well-known CFD-based Fire Dynamics Simulator for creating a series of didactic videos is illustrated. The videos demonstrate the smoke propagation and time evolution of temperature, air flow velocity and visibility for selected fire scenarios. They have been implemented into the TTOS environment and became available for tunnel operators.

Systems approach to underground safety

The safety of underground traffic infrastructures can be considered from several viewpoints as a fairly mature field. Common minimum requirements for road tunnel safety were developed for all European countries in 2004. Furthermore, safety is codified in a detailed (at times even too detailed) manner, such as for road tunnels in several countries. Safety design can at times be extremely rigid and difficult for adapting to specific conditions, which in some cases may need to be more demanding than a “standard” tunnel.Other types of underground infrastructure, particularly, rail tunnels and underground industrial facilities, share a number of common safety-related issues with road tunnels, but are generally much less regulated. For example, there is no common regulation for the ventilation of rail tunnels in Europe. Various metro systems have different safety standards, in spite of having similar requirements.The present study illustrates selected aspects of a holistic approach required for achieving a high and sustainable safety level in underground infrastructure. Common aspects and differences between the various types of “conventional” and “emerging” underground infrastructure are outlined and the consequences are discussed, such as the different types of threats, widely differing probabilities of occurrence, and widely differing number of persons exposed. Different facilities require different safety systems; however, they can rely on common thinking and philosophies.It is essential for all stakeholders, ranging from operators and safety officers to fire services and administrative authorities, to grasp commonalities and differences to adapt requirements, regulations, and approaches to their specific needs.

Overview of research on fire safety in underground road and railway tunnels

In the past two decades, the interest in fire safety science of tunnels has significantly increased, mainly due to the rapidly increasing number of tunnels built and the catastrophic tunnel fire incidents occurred. This paper presents an overview of research on fire safety in underground road and railway tunnels from the perspectives of fire safety design. The main focuses are on design fires, structural protection, smoke control and use of water-based fire suppression systems. Besides, some key fire characteristics, including flame length, fire spread, heat flux and smoke stratification, are discussed.

Applying a stochastic-based approach for developing a quantitative risk assessment method on the fire safety of underground road tunnels

Fire safety is an important aspect of underground road tunnels’ operation. Undertaking high traffic volumes, they are one of the most critical infrastructure for the daily operation of modern urban networks. Aiming to guarantee their safety, risk assessment has been established as a valuable tool. However, the deterministic approach of existing methods has weaknesses in addressing the embedded uncertainty included in important parameters of the system. This paper, applying a stochastic-based approach, proposes a novel quantitative risk assessment method, named SIREN. Initially, the system’s parameters are investigated and the ones which should be treated as stochastic are identified. Subsequently, the method considers both tunnel airflows and trapped-users’ evacuation in order to estimate their potential losses. Finally, the system’s level of safety is provided through the distribution of the trapped-users losses, which occurred by accumulating the results that derived from the Monte Carlo Simulation. The proposed method is illustrated through the case of an urban underground road tunnel during rush hour. The outcome highlights a significant proportion of scenarios that exceed the number of losses estimated by the traditional methods. Meanwhile, the method examines the parameters’ criticality supporting, thus, safety analysts in selecting additional to standard safety measures, if needed. Furthermore, the proposed method aids analysts to act consistently with the as low as reasonable practicable principle.

Measurements and fire simulation models in road tunnels

Ventilation system of road tunnel is one of the most important parts of the tunnel safety equipment, especially in view of the emergency event in the tunnel with fire. Last year we presented the testing and the first in situ measurements of our project entitled “Models of formation and spread of fire to increase safety of road tunnels”. With regard to our project schedule we performed also the second in situ experiment. Other part of this paper deals with computer simulations of fires of a selected Slovak road tunnel.