The Experts below are selected from a list of 5028 Experts worldwide ranked by ideXlab platform
Qiang Meng - One of the best experts on this subject based on the ideXlab platform.
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estimation of rear end vehicle crash frequencies in urban Road Tunnels
Accident Analysis & Prevention, 2012Co-Authors: Qiang MengAbstract:According to The Handbook of Tunnel Fire Safety, over 90% (55 out of 61 cases) of fires in Road Tunnels are caused by vehicle crashes (especially rear-end crashes). It is thus important to develop a proper methodology that is able to estimate the rear-end vehicle crash frequency in Road Tunnels. In this paper, we first analyze the time to collision (TTC) data collected from two Road Tunnels of Singapore and conclude that Inverse Gaussian distribution is the best-fitted distribution to the TTC data. An Inverse Gaussian regression model is hence used to establish the relationship between the TTC and its contributing factors. We then proceed to introduce a new concept of exposure to traffic conflicts as the mean sojourn time in a given time period that vehicles are exposed to dangerous scenarios, namely, the TTC is lower than a predetermined threshold value. We further establish the relationship between the proposed exposure to traffic conflicts and crash count by using negative binomial regression models. Based on the limited data samples used in this study, the negative binomial regression models perform well although a further study using more data is needed.
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Estimation of number of fatalities caused by toxic gases due to fire in Road Tunnels.
Accident; analysis and prevention, 2012Co-Authors: Qiang Meng, Zhiyuan LiuAbstract:The quantitative risk assessment (QRA) is one of the explicit requirements under the European Union (EU) Directive (2004/54/EC). As part of this, it is essential to be able to estimate the number of fatalities in different accident scenarios. In this paper, a tangible methodology is developed to estimate the number of fatalities caused by toxic gases due to fire in Road Tunnels by incorporating traffic flow and the spread of fire in Tunnels. First, a deterministic queuing model is proposed to calculate the number of people at risk, by taking into account tunnel geometry, traffic flow patterns, and incident response plans for Road Tunnels. Second, the Fire Dynamics Simulator (FDS) is used to obtain the temperature and concentrations of CO, CO2, and O2. By taking advantage of the additivity of the fractional effective dose (FED) method, fatality rates for different locations in given time periods can be estimated. An illustrative case study is carried out to demonstrate the applicability of the proposed methodology.
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Uncertainty Propagation in Quantitative Risk Assessment Modeling for Fire in Road Tunnels
IEEE Transactions on Systems Man and Cybernetics Part C (Applications and Reviews), 2012Co-Authors: Qiang Meng, Xiaobo QuAbstract:Road Tunnels are critical transportation infrastructures that provide underground passageways for motorists and commuters. Fire in Road Tunnels in combination with tunnel safety provisions failure may lead to catastrophic consequences, and thus, necessitates a robust and reliable approach to assess tunnel risks. This article proposes a quantitative risk assessment model for fire in Road tunnel by taking into consideration two types of uncertainties. A Monte Carlo-based estimation method is developed to propagate parameter uncertainty in quantitative risk assessment model consisting of event tree analysis as well as consequence estimation models. The percentile-based individual risks and α-cut-based societal risks are put up and the risk indices are proven to be very useful for tunnel operators with distinct risk attitudes to assess the safety level of a Road tunnel. Finally, the proposed research methodology is applied to Singapore KPE Road Tunnels.
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qra model based risk impact analysis of traffic flow in urban Road Tunnels
Risk Analysis, 2011Co-Authors: Qiang Meng, Kum Thong Yong, Yoke Heng WongAbstract:This article describes how Road Tunnels are vital infrastructures that provide underground vehicular passageways for commuters and motorists. Various quantitative risk assessment (QRA) models have recently been developed and employed to evaluate the safety levels of Road Tunnels in terms of societal risk. For a particular Road tunnel, traffic volume and the proportion of heavy goods vehicles (HGVs) are two adjustable parameters that may significantly affect the societal risk, and are very useful in implementing risk reduction solutions. In order to evaluate the impact these two contributing factors have on risk, this article first presents an approach that employs a QRA model to generate societal risk for a series of possible combinations of the two factors. Some combinations may result in F/N curves that do not fulfill a predetermined safety target. This article proposes an “excess risk index” to quantify the Road tunnel risk magnitudes that do not pass the safety target. The two-factor impact analysis can be illustrated by a contour chart based on the excess risk. Finally, the methodology presented in this article has been applied to Singapore’s KPE Road tunnel and the results show that in terms of meeting the test safety target for societal risk, the traffic capacity of the tunnel should be no more than 1,200 vehicles per hour per lane, with a maximum proportion of 18% HGVs.
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design and implementation of a quantitative risk assessment software tool for singapore Road Tunnels
Expert Systems With Applications, 2011Co-Authors: Qiang Meng, Vivi Yuanita, Yoke Heng WongAbstract:This paper presents an interesting approach to develop a quantitative risk assessment (QRA) software tool for Road Tunnels. It first introduces a QRA model for Road Tunnels, consisting of event trees, fault trees and consequence estimation models. The model is developed by taking into account the unique characteristics of Singapore Road Tunnels. The paper proceeds to describe design of the QRA software tool based on the QRA model by means of the object oriented design (OOD) method and eXtensible Markup Language (XML) technique. The XML files are used to store the numerous tree structures in the proposed model thus making the programming much more efficiently and effectively. The QRA software tool is robust and flexible such that users can easily add or modify the event trees, fault trees and the consequence estimation models. An application to Singapore Road Tunnels has been carried out to assess the robustness and effectiveness of the QRA software tool.
Antonio Penagarcia - One of the best experts on this subject based on the ideXlab platform.
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determination of lighting and energy demands of Road Tunnels using vehicle based photographs of the portal gates an accessible and safe tool for tunnel renewal and maintenance
Tunnelling and Underground Space Technology, 2018Co-Authors: J C Lopez, Antonio PenagarciaAbstract:Abstract Strategies to make the lighting installations of Road Tunnels more sustainable constitute a challenging line of research due to the difficulty of decreasing consumption and use of raw materials without impairing traffic safety. The first challenge when designing or optimizing these installations arises at the tunnel access, where the lighting requirements of the whole infrastructure must be determined as a function of several characteristics of the tunnel and its surroundings. This is the determination of the L20 luminance, that nowadays is still controversial due to the important differences between the methods established by the standards and regulations and the technical difficulties to implement them. In this work, a simple and safe method to easily calculate the L20 luminance in Tunnels already open to traffic without expensive instruments nor risks for operators is presented. The equations to determine the radius of the L20 cone basis are developed and the potential errors analyzed. Some examples illustrate the methodology and validate it.
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a proposal for evaluation of energy consumption and sustainability of Road Tunnels the sustainability vector
Tunnelling and Underground Space Technology, 2017Co-Authors: J C Lopez, A L Grindlay, Antonio PenagarciaAbstract:Abstract In the last years, besides traffic safety, two aspects of Road Tunnels have become really critical: energy consumption of the lighting installations and landscape integration of the portal gate. However, both aspects have been considered from different perspectives, and their development and advances seem to follow separate paths. In this work, energy consumption and landscape integration, together with the cost of portal construction, are proven to be strongly related when considered from the common framework of sustainability and its implications in a necessary global Policy for Road Tunnels. Departing from the evaluation of real Tunnels in a real highway, three quantitative parameters ranged from 0 to 5 (energy consumption parameter, landscape integration parameter and construction cost parameter) are proposed to build a more general tool, the sustainability vector, that gives account of the degree of sustainability and highlights the necessity of corrective actions when necessary. Depending on the values of its module and director angle, a labeling system ranging from A to D, is proposed for the use of Regulatory Bodies and Public Administrations in matter of tunnel classification and sustainability requirements. According to this system, two of the tubes analyzed reach the “A” labeling, whereas two are “B” and six are “D”.
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use of sunlight in Road Tunnels an approach to the improvement of light pipes efficacy through heliostats
Tunnelling and Underground Space Technology, 2016Co-Authors: Antonio Penagarcia, Luisa Maria Gilmartin, Enrique HernandezmontesAbstract:Abstract A coupled system consisting on a heliostat and a matrix of light-pipes inside one Road tunnel where the heliostat injects sunlight, is proposed. Its reliability and efficiency from theoretical calculations and a mock-up, is analyzed as a function of tunnel orientation. The heliostat is fixed above the Road some meters before the portal gate of the Road Tunnels. It continuously seeks the correct orientation so that the angle between sun, heliostat and light-pipes in the portal gate, injects of parallel sunrays every moment. Then, these rays are guided through the light-pipes and distributed on the Road in the threshold zone with a remarkable improvement of the efficacy of light-pipes and the relevant savings in electrical consumption and number of luminaries. The results of calculations and measurements on mock-up, that show energy savings above 20% in the most favorable tunnel orientations and 14% in arbitrary orientations, as well as a discussion about the most accurate tunnel orientations are analyzed and presented.
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use of diffusers materials to improve the homogeneity of sunlight under pergolas installed in Road Tunnels portals for energy savings
Tunnelling and Underground Space Technology, 2015Co-Authors: Luisa Maria Gilmartin, A Gomezguzman, Antonio PenagarciaAbstract:Abstract In spite of the benefits of shifting the threshold zone of Road Tunnels by means of pergolas, installed before their portal to save energy in the electrical lighting, the lack of uniformity in the Road under these structures makes them a non accurate solution in terms of visual performance and, hence, Road safety. In this work, a new solution, consisting on the introduction of a diffuser material in the spaces between beams of the pergola is proposed. The measurements and results in a scale mock-up, a computational simulation and the comparison with a theoretical model, as well as the potential impact in real Tunnels are presented and analyzed.
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decrease of energy demands of lighting installations in Road Tunnels based in the forestation of portal surroundings with climbing plants
Tunnelling and Underground Space Technology, 2015Co-Authors: Antonio Penagarcia, J C Lopez, A L GrindlayAbstract:Abstract The lighting installations demand the biggest part of the energy consumed in Road Tunnels. This demand is much higher during daytime, when the visual adaptation of the drivers coming from bright environments, requests very intense illumination levels, especially in the first part of the tunnel, the so called threshold zone. The lighting necessities in Road Tunnels depend on three main critical parameters: maximum speed allowed in the tunnel, tunnel orientation and the characteristics of the portal gate surroundings. In this work, actions on this last parameter have been evaluated: four different species of climbing plants have been tested as candidates to forest the surroundings of portal gates in an environment of Mediterranean climate. The lighting demands in the threshold zone arising from the choice of each species have been quantified by luminance measurement. As a result, the common ivy ( Hedera helix ) is proposed as the best candidate to fully forest the surroundings of portal gates optimizing the binomial energy consumption-landscape integration in a Mediterranean climate.
Vincent Labiouse - One of the best experts on this subject based on the ideXlab platform.
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identification and analysis of swiss national Road Tunnels pathologies
Tunnelling and Underground Space Technology, 2011Co-Authors: Federica Sandrone, Vincent LabiouseAbstract:In order to evaluate the general conditions (i.e. safety, serviceability and durability) of Tunnels, a detailed analysis of the lining structure and surrounding rock mass is required. During the service life of the tunnel, regular survey activities should be performed to check the tunnel conditions and regular conservation practices are necessary to preserve the tunnel’s structural integrity and guarantee safety and serviceability during operation. The collection of data about Tunnels since their construction and during their service life may help in the assessment of tunnel conditions and improve the understanding of tunnel degradation with time. The long term behaviour of the Swiss National Road Tunnels has been studied and a specific data base has been developed. Based on detailed literature review and analysis of principal inspections results collected in the data base, the main pathologies that affect the Swiss Road Tunnels have been identified. In addition, by means of a specific data analysis, both degradation potential and rate have been investigated and the main influence factors involved have been selected. The obtained results confirm what was expected according to observations in the past. After a brief introduction about the Tunnels of the National Roads network, this paper describes the main steps of the data analysis, different methods used and main results of the analysis. Due to the fact that the Tunnels within Swiss National Roads were developed during the 60s, attention has been focused only on concrete lined Tunnels.
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Analysis of the evolution of Road Tunnels equilibrium conditions with a convergence–confinement approach
Rock Mechanics and Rock Engineering, 2010Co-Authors: Federica Sandrone, Vincent LabiouseAbstract:Since both lining structure and rock mass exhibit delayed behaviour, tunnel equilibrium conditions evolve with time. After discussing existing work done on different aspects of long-term tunnel behaviour, the aim of this paper is to “understand” the influence of rock mass and lining degradations on the long-term stability conditions of the tunnel by means of the convergence–confinement method. In order to represent the effects of degradation on tunnel long-term conditions, specific degradation models are selected according to the disorders identified during principal inspections of Road Tunnels in Switzerland. By simulating the reduction of the mechanical properties of both the rock mass and the lining or by using creep models, it is possible to assess the influence of the main degradation processes on tunnel stability. The results are interpreted in terms of tunnel safety factor. The presented approach for the determination of the long-term behaviour of Tunnels, although valid for simple tunnel geometry and field stress conditions, allows to roughly estimate the influence of significant degradation processes that affect the rock mass and the supporting structure. Though this approach results in some simplification, it may be generalised and adopted with more refined numerical analyses for improving the assessment of tunnel long-term conditions.
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analysis of the evolution of Road Tunnels equilibrium conditions with a convergence confinement approach
Rock Mechanics and Rock Engineering, 2010Co-Authors: Federica Sandrone, Vincent LabiouseAbstract:Since both lining structure and rock mass exhibit delayed behaviour, tunnel equilibrium conditions evolve with time. After discussing existing work done on different aspects of long-term tunnel behaviour, the aim of this paper is to “understand” the influence of rock mass and lining degradations on the long-term stability conditions of the tunnel by means of the convergence–confinement method. In order to represent the effects of degradation on tunnel long-term conditions, specific degradation models are selected according to the disorders identified during principal inspections of Road Tunnels in Switzerland. By simulating the reduction of the mechanical properties of both the rock mass and the lining or by using creep models, it is possible to assess the influence of the main degradation processes on tunnel stability. The results are interpreted in terms of tunnel safety factor. The presented approach for the determination of the long-term behaviour of Tunnels, although valid for simple tunnel geometry and field stress conditions, allows to roughly estimate the influence of significant degradation processes that affect the rock mass and the supporting structure. Though this approach results in some simplification, it may be generalised and adopted with more refined numerical analyses for improving the assessment of tunnel long-term conditions.
Luisa Maria Gilmartin - One of the best experts on this subject based on the ideXlab platform.
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use of sunlight in Road Tunnels an approach to the improvement of light pipes efficacy through heliostats
Tunnelling and Underground Space Technology, 2016Co-Authors: Antonio Penagarcia, Luisa Maria Gilmartin, Enrique HernandezmontesAbstract:Abstract A coupled system consisting on a heliostat and a matrix of light-pipes inside one Road tunnel where the heliostat injects sunlight, is proposed. Its reliability and efficiency from theoretical calculations and a mock-up, is analyzed as a function of tunnel orientation. The heliostat is fixed above the Road some meters before the portal gate of the Road Tunnels. It continuously seeks the correct orientation so that the angle between sun, heliostat and light-pipes in the portal gate, injects of parallel sunrays every moment. Then, these rays are guided through the light-pipes and distributed on the Road in the threshold zone with a remarkable improvement of the efficacy of light-pipes and the relevant savings in electrical consumption and number of luminaries. The results of calculations and measurements on mock-up, that show energy savings above 20% in the most favorable tunnel orientations and 14% in arbitrary orientations, as well as a discussion about the most accurate tunnel orientations are analyzed and presented.
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use of diffusers materials to improve the homogeneity of sunlight under pergolas installed in Road Tunnels portals for energy savings
Tunnelling and Underground Space Technology, 2015Co-Authors: Luisa Maria Gilmartin, A Gomezguzman, Antonio PenagarciaAbstract:Abstract In spite of the benefits of shifting the threshold zone of Road Tunnels by means of pergolas, installed before their portal to save energy in the electrical lighting, the lack of uniformity in the Road under these structures makes them a non accurate solution in terms of visual performance and, hence, Road safety. In this work, a new solution, consisting on the introduction of a diffuser material in the spaces between beams of the pergola is proposed. The measurements and results in a scale mock-up, a computational simulation and the comparison with a theoretical model, as well as the potential impact in real Tunnels are presented and analyzed.
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study of light pipes for the use of sunlight in Road Tunnels from a scale model to real Tunnels
Tunnelling and Underground Space Technology, 2014Co-Authors: Luisa Maria Gilmartin, Antonio Penagarcia, A Jimenez, Enrique HernandezmontesAbstract:Abstract The necessity of saving energy from the electrical lighting in Road Tunnels demands alternative solutions, especially concerning the use of the cheapest and most ecological light source: the sun. In this work, the principles of sunlight distribution inside the Tunnels themselves by means of light-pipes are developed and considered. The study is based on a scale model in which exhaustive calibration and adaptation to the situation in real Tunnels is presented and discussed. Finally, the advantages of the philosophy of light distribution versus other means of using sunlight in Road Tunnels are analyzed and highlighted.
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study of pergolas for energy savings in Road Tunnels comparison with tension structures
Tunnelling and Underground Space Technology, 2013Co-Authors: Antonio Penagarcia, Luisa Maria GilmartinAbstract:Abstract The huge consumption and environmental impact of electrical lighting in Road Tunnels in terms of energy, materials and maintenance, has evidenced the necessity of using solar light for tunnel lighting during daytime. One satisfactory solution has been to shift the threshold zone out of the tunnel by means of tension structures. Although pergolas in the portal gate of Road Tunnels have been mainly used for structural purposes, they have been also claimed as a co-lateral solution to achieve this target. In this work, the theoretical basis of the ad hoc use of pergolas for energy savings in Road Tunnels are developed, analyzed and compared with tension structures. General expressions for the light distribution under any arbitrary pergola, not reported in the reviewed literature for this study, are presented and the ESTS equation, used for energetic evaluation of tension structures, is also generalized to the case of pergolas. Finally, the accuracy of pergolas for normative compliance in matter of illumination is discussed and several important conclusions are presented.
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computational optimization of semi transparent tension structures for the use of solar light in Road Tunnels
Tunnelling and Underground Space Technology, 2012Co-Authors: Antonio Penagarcia, Luisa Maria Gilmartin, R Escribano, A EspinestrellaAbstract:Abstract The installation of semi-transparent tension structures in the entrance portal of Road Tunnels leads to significant energy savings. These savings can be maximized when the tensions structures are designed in such a way that their material and shape contribute to their optimal photometric and mechanical performance. In this research, a graphic design software in the field of light simulation has been used and combined with the ESTS equation, developed in a previous study, to simulate tension structures with three different shapes and three different materials. Nine possible combinations were thus tested. The results obtained show that this new method is a quick, inexpensive, and safe way to optimize the material and shape of the tension structure installed at the entrance portal of a Road tunnel, regardless of its orientation and location.
Federica Sandrone - One of the best experts on this subject based on the ideXlab platform.
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identification and analysis of swiss national Road Tunnels pathologies
Tunnelling and Underground Space Technology, 2011Co-Authors: Federica Sandrone, Vincent LabiouseAbstract:In order to evaluate the general conditions (i.e. safety, serviceability and durability) of Tunnels, a detailed analysis of the lining structure and surrounding rock mass is required. During the service life of the tunnel, regular survey activities should be performed to check the tunnel conditions and regular conservation practices are necessary to preserve the tunnel’s structural integrity and guarantee safety and serviceability during operation. The collection of data about Tunnels since their construction and during their service life may help in the assessment of tunnel conditions and improve the understanding of tunnel degradation with time. The long term behaviour of the Swiss National Road Tunnels has been studied and a specific data base has been developed. Based on detailed literature review and analysis of principal inspections results collected in the data base, the main pathologies that affect the Swiss Road Tunnels have been identified. In addition, by means of a specific data analysis, both degradation potential and rate have been investigated and the main influence factors involved have been selected. The obtained results confirm what was expected according to observations in the past. After a brief introduction about the Tunnels of the National Roads network, this paper describes the main steps of the data analysis, different methods used and main results of the analysis. Due to the fact that the Tunnels within Swiss National Roads were developed during the 60s, attention has been focused only on concrete lined Tunnels.
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Analysis of the evolution of Road Tunnels equilibrium conditions with a convergence–confinement approach
Rock Mechanics and Rock Engineering, 2010Co-Authors: Federica Sandrone, Vincent LabiouseAbstract:Since both lining structure and rock mass exhibit delayed behaviour, tunnel equilibrium conditions evolve with time. After discussing existing work done on different aspects of long-term tunnel behaviour, the aim of this paper is to “understand” the influence of rock mass and lining degradations on the long-term stability conditions of the tunnel by means of the convergence–confinement method. In order to represent the effects of degradation on tunnel long-term conditions, specific degradation models are selected according to the disorders identified during principal inspections of Road Tunnels in Switzerland. By simulating the reduction of the mechanical properties of both the rock mass and the lining or by using creep models, it is possible to assess the influence of the main degradation processes on tunnel stability. The results are interpreted in terms of tunnel safety factor. The presented approach for the determination of the long-term behaviour of Tunnels, although valid for simple tunnel geometry and field stress conditions, allows to roughly estimate the influence of significant degradation processes that affect the rock mass and the supporting structure. Though this approach results in some simplification, it may be generalised and adopted with more refined numerical analyses for improving the assessment of tunnel long-term conditions.
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analysis of the evolution of Road Tunnels equilibrium conditions with a convergence confinement approach
Rock Mechanics and Rock Engineering, 2010Co-Authors: Federica Sandrone, Vincent LabiouseAbstract:Since both lining structure and rock mass exhibit delayed behaviour, tunnel equilibrium conditions evolve with time. After discussing existing work done on different aspects of long-term tunnel behaviour, the aim of this paper is to “understand” the influence of rock mass and lining degradations on the long-term stability conditions of the tunnel by means of the convergence–confinement method. In order to represent the effects of degradation on tunnel long-term conditions, specific degradation models are selected according to the disorders identified during principal inspections of Road Tunnels in Switzerland. By simulating the reduction of the mechanical properties of both the rock mass and the lining or by using creep models, it is possible to assess the influence of the main degradation processes on tunnel stability. The results are interpreted in terms of tunnel safety factor. The presented approach for the determination of the long-term behaviour of Tunnels, although valid for simple tunnel geometry and field stress conditions, allows to roughly estimate the influence of significant degradation processes that affect the rock mass and the supporting structure. Though this approach results in some simplification, it may be generalised and adopted with more refined numerical analyses for improving the assessment of tunnel long-term conditions.
