Kapitel

• Sustainability of tunnel operation: New approaches – a PIARC briefing note and collection of case studiesList, René; PIARC Technical Committee, Working Group; 10.3217/978-3-99161-087-8-001Sustainability means creating a new economic and social model that can respond to today’s environmental challenges. Applied to road tunnels, this concept includes the environmental aspects of reducing energy consumption and emissions and minimizing impacts over the tunnel’s full life cycle. The economic aspects of modern road tunnels focus on keeping costs under control over time, supporting innovation, and helping create local jobs. Ultimately, the social aspects, which are about making tunnels safe, accessible, and well-integrated into their urban surroundings must not be left out of consideration. In this context, road authorities and infrastructure managers are increasingly expected to promote energy efficiency and adopt sustainable methods for the construction and operation of public roads including road tunnels. A large part of the operational expenditure in this regard is related to the provision and consumption of electrical energy. Considering that road tunnels are complex and costly objects with a life cycle of typically more than 80 years, it becomes clear that a concept for sustainable and energy-efficient road tunnel operation is of great importance. The aim of this briefing note including a collection of case studies was therefore to gather, evaluate and comment on international expertise related to measures aiming at the design and operation of road tunnels in a more sustainable way.
• The Koralmtunnel as a real-world laboratory: Research work and findings during the construction of the KoralmtunnelSteiner, Helmut; Bacher, Michael; Fruhwirt, Daniel; 10.3217/978-3-99161-087-8-002The Koralm Tunnel (KAT) was used as a real-world laboratory during the mechanical equipment phase and commissioning in order to investigate a range of operational, safety-related, and aerodynamic phenomena under realistic high-speed railway conditions. A series of coordinated experimental and measurement campaigns were conducted to generate data relevant for tunnel design validation, system commissioning, and future tunnel projects. Dust exposure levels were investigated during high-speed train movements to assess occupational safety conditions and to evaluate particle transport mechanisms within the tunnel system. Based on these measurements, the service life of ventilation and technical room filters was determined under representative operating conditions. Pressure loads induced by train passages were measured both in the tunnel and within adjacent technical rooms, providing insight into transient pressure propagation and structural loading of technical installations. The behaviour of pantographs during high-speed operation investigated using CFD simulations in order to determine the contact force between the pantograph head and the fixed catenary. The aim is to use this information to prevent arcing and burn marks on the the fixed catenary. In parallel, wall friction was determined using pressure and velocity measurements, contributing to an improved understanding of resistance effects relevant for ventilation design and energy demand. Aerodynamic processes in the cross passages and the unterground evacuation and rescue point (EVRP) were investigated to evaluate airflow patterns and pressure interactions under train-induced flow conditions. In addition, meteorological pressure differences between the tunnel portals were recorded and analysed to quantify their influence on longitudinal airflow and pressure balance within the tunnel system. The results provide valuable experimental data for validating numerical models, supporting commissioning activities, and improving the design and operation of future long railway tunnels subjected to high-speed traffic.
• ASFINAG in case of a blackout – overview and measuresRattei, Günter; Mahr-Saverschel, Alice; 10.3217/978-3-99161-087-8-003ASFINAG is part of critical infrastructure and must be prepared for a blackout. A detailed emergency plan and over 70 concepts ensure safe and quick emergency operations, maintain communication, and keep roads open to guarantee security and stability during the crisis.
• Safe tunnels for smart vehicles: Challenges and opportunities of automated driving in road tunnelsSchmidt, Regina; Kammerer, Harald; Mayer, Georg; Hofer, Markus; Zendel, Oliver; 10.3217/978-3-99161-087-8-004The digitalization of traffic infrastructure is a key enabler for connected and automated driving. Automated vehicles will increasingly interact seamlessly with infrastructure, offering significant potential to reduce accidents and enhance both safety and road capacity. However, tunnels present unique challenges due to their specific safety requirements and the absence of Global Navigation Satellite System (GNSS) signals, which complicates accurate vehicle localization. Radio-based positioning systems also face issues such as multipath propagation caused by reflections in tunnel environments. Current solutions focus primarily on vehicle-based sensors, but these have limitations in tunnels. The research project AUDIT analyses localization by vehicle-based sensors as well as Cooperative Intelligent Transport Systems (C-ITS), which enable continuous bidirectional data exchange between vehicles and infrastructure. Safety impacts are assessed using systematic risk analysis methods, considering Society of Automotive Engineers (SAE) automation levels and mixed traffic scenarios. The project also discusses the effects on tunnel operations under both normal and emergency conditions from the operator’s as well as tunnel user’s perspective. Feasibility studies in Austrian and German tunnels will validate promising technologies for supporting automated driving in road tunnels. A dedicated test vehicle equipped with multiple sensors and communication modules collects comprehensive data to evaluate positioning accuracy and communication reliability. The findings will provide recommendations for sensor configurations, infrastructure adaptations, and operational protocols, including cost-benefit considerations. Ultimately, the project aims to provide actionable solutions for safe and efficient automated driving in tunnels, contributing to the development of unified standards and best practices for integrating automated vehicles into future transport systems.
• Conformity bias influence on walking speed in a smoke-filled tunnel experimentSeike, Miho; Li, Wenhao; Futagami, Takao; 10.3217/978-3-99161-087-8-005The influence of information from people - referred to as conformity bias in this study - during an actual evacuation owing to a tunnel fire has not been clarified, despite the high number of people present in the same area during such an event. Therefore, in this study, we conducted an experiment focusing on the peoples’ behavior upon seeing another evacuee moving in the wrong direction. The test was conducted using a full-scale road tunnel (50 m in length and 6 m in width) in the Fukushima robot test field. We simulated a darkened environment caused by smoke. The smoke was a mixture of water and glycol, ensuring it was non-irritant and non-toxic. Many tunnels in Asia, including Japan, have not installed a guide light function other than the guide board. Obstacles were set-up in the form of a small truck and van. The participants were not informed that a person moving in the wrong direction (staff member) would pass them along the way. Walking speed was calculated based on the speed before the participant encountered the staff member and after the encounter. The participants were made up of 20 men (average age of 42.6 years). The speeds of 12 participants (60%) decreased after the staff member had passed them.
• Impact of group effects on the reaction and escape behaviour of users in road tunnels - results of realistic large group experimentsLeismann, Frank; Thienert, Christian; Jenki, Markus; Wenighofer, Robert; Lehan, Anne; Stühler, David; Czudnochowski, David; Kaufmann, Stefan; Galler, Robert; 10.3217/978-3-99161-087-8-006The German Federal Highway and Transport Research Institute (BASt) initiated a research project that systematically investigated the influence of group effects on escape behaviour during self-rescue in road tunnels. As previous studies had shown that collective decision-making can delay the self-rescue process compared to a “single-person decision”, large-group tests were conducted. The study took place in a highly realistic road tunnel environment at the “Zentrum am Berg (ZaB)” in Austria involving a total of 5 large group tests (73 test persons and 47 vehicles), as well as 7 individual reference tests of single drivers. The scenario considered was a vehicle collision leading to a lorry fire in a bi-directional traffic setting, which was realistically simulated by using gas burners and smoke. Participants drove into the tunnel in their own cars without any prior knowledge of what to expect. Their perceptions, decisions and behaviour upon first recognising the accident site, approaching it, getting out of the vehicle, finding their way in the tunnel and escaping were documented in detail via “on-scene” interviews in the tunnel, follow-up interviews and video recordings. The tests were analysed from a sociological perspective in order to determine types of behaviour and critical situations. Further analysis from an engineering perspective was executed in order to obtain relevant parameters such as reaction and escape times. The paper points out the most significant results from the large group tests focusing on quantitative parameters such as reaction times and evacuation speed. The numbers found are higher than the reference values for the single-person test. However, these results remain within the range of the values commonly used in risk analyses, meaning no specific adjustments to the current regulations are required. In addition, selected results from the behavioural analyses are presented briefly.
• Digital Twins for road tunnels – expectations meet realityVollmann, Goetz; Azad, Zuzan; Von Roessing, Lisa; Faltin, Benedikt; Lehan, Anne; Nono Tamo, Marius; Hanke, Karl; Jodehl, Annika; 10.3217/978-3-99161-087-8-007The German Ministry of transport (BMV) recently published a guideline that defines the basic features of Digital Twins (DT) in the course of the German federal road network and outlines their areas of application. While tunnels already require at least a partially digital environment, which is determined by existing regulations and their implementation, any type of DT must fit into these processes and regulative schemes. In doing so it will automatically redesign and redefine them in order to activate its full potential. That said, safety concerns are raised and need to be addressed. Moreover, the Kritis Regulation of the Federal Office of Information Security (BSI) categorises tunnel control centres as critical infrastructure facilities. Therefore, the number of processes that can be handed over to a DT is already limited due to security implications. In the DIDYMOS project, the research partners are developing methods and processes for setting up DT for road tunnels, with the aim to implement them as a part of optimized operating approaches. In this context, the authors conducted extensive interviews with all stakeholder groups involved in tunnel operation. The results of the interviews show that, on the one hand, there is great curiosity about such approaches, but on the other hand, substantial concerns have been expressed as to whether tunnel operation needs to be redefined and reorganized if a DT is to be introduced into everyday operations. The interviews also address which tunnel operation tasks can or may be automated by DTs. In this article, the authors present a summary of the interview results and highlight where stakeholder expectations and technical implementation concepts correlate or conflict with each other. Furthermore, preliminary dashboards of the developmental DT and how analyses can be carried out for the daily work are presented.
• R&D project tunnel sensor fusionHarbauer, Dietmar; 10.3217/978-3-99161-087-8-008This paper describes the processes and results of an R&D project implemented by the author in the context of his work for ASFINAG. Thanks to intelligent sensor data fusion it could be shown that the detection probability of events in road tunnels can be increased significantly while at the same time markedly reducing false positives. The project was tested in three ASFINAG (Austrian Corporation for the Funding, Construction and Operation of the Country's High-Ranking Road Network) tunnels.
• Development of a systematic approach for evaluation of the condition of the tunnel equipmentLehan, Anne; Hudecek, Gerhard; Kammerer, Harald; Heim, Frank; 10.3217/978-3-99161-087-8-009Road tunnels play a central role in ensuring the efficiency of the road transport network. Maintaining their availability and safety is therefore of great importance. To ensure this, the condition of the structures must be regularly recorded, documented and evaluated. The structural inspection of road tunnels in the federal trunk road network in Germany is carried out according to a systematised procedure in accordance with DIN 1076, although the focus is primarily on the structural condition assessment. The question of the condition of the operational and safety-related tunnel equipment remains largely unanswered. This is recorded and summarised via regular maintenance and inspection. To date, it has not been summarised, e.g. by means of a condition mark as for the structure. In Austria, an evaluation methodology for operational equipment already exists, but it is to be updated based on experience gained from its application. As part of a research project by the Federal Highway and Transport Research Institute, a system for assessing the condition of operational and safety equipment has therefore been developed. This provides a basis for forecasting the availability and necessary maintenance measures for the tunnel equipment in Germany and will thus be available in future as additional information alongside the condition rating for the structure. For this purpose, practical evaluation criteria and an evaluation methodology were developed, and weighting approaches for the various equipment components were studied to take into account their relevance to tunnel safety. In addition, further parameters were defined to consider the importance of the tunnel in the road network for prioritization of measures. This article presents the results of the study and highlights the challenges involved in developing and applying the system, the findings of the evaluation of the system on a specific structure, and the steps required to further refine the system for application.
• Methodology for the performance enhancement of longitudinal ventilation systems during transient stage of a firedel Moral, Miguel; Gratch, Alexander; D’Eustacchio, Davide; Meneses, Álvaro; Suarez, Justo; 10.3217/978-3-99161-087-8-010Ventilation systems in tunnels are designed for a maximum fire load. However, during the initial stages of a fire, the fire would not be completely developed and the activation of the system at maximum speed may disrupt smoke stratification, compromising occupants’ evacuation. This paper presents a methodology to assist designers in defining the optimal activation protocol for a longitudinal ventilation system, focusing on the response of the ventilation system during the transient stage of the fire. This methodology would aim to: 1. Enhance Available Safe Egress Time (ASET) over Required Safe Egress Time (RSET). 2. Assess the effectiveness and robustness of the ventilation system and its response in the design stages. 3. Help to define the safest procedures for the control centers, advising on how to operate the ventilation system depending on the real conditions in the event of a fire. The methodology is presented in a case study, which is provided with a longitudinal ventilation system designed to achieve a specific air velocity for a given fire load. This methodology is not limited to a specific critical/confinement velocity model and a different formulation is also assessed in the process for comparison. For the case study and the considered model, critical/confinement velocity is numerically estimated along time to serve as starting point in the process of defining the activation protocol for the ventilation system. This considers both sequential activation for jet fans and activation through variable speed drive. Once the activation protocol is defined, the effectiveness of the response is assessed through Computational Fluid Dynamics (CFD) software, and the results are analyzed together with models for Required Safe Egress Time.
• Performance improvement of a hybrid ventilation system via predictive controlAngeli, Diego; Levoni, Paolo; Cingi, Pietro; Barozzi, Giovanni Sebastiano; Verraz, Paolo; Petitcolin, Cedric; 10.3217/978-3-99161-087-8-011Accurate and responsive ventilation control is of primary importance in the airflow management in tunnels, especially in the case of fire events. This is even more critical in long single-tube, two-way road tunnels such as the Mont Blanc Tunnel, where the ventilation system is hybrid (longitudinal and transverse), and smoke must be confined and conveyed to suitable ceiling vents connected to an extraction shaft, while stratification must be kept as stable as possible. Jet fans are employed to realize the confinement, coupled with a PID controller which acts on the velocity excess in the position of the fire event, with the aim of nullifying it in the shortest possible time. The action of the controller is crucially subject to the action of several different factors: (i) the barometric pressure difference between portals, (ii) the accuracy and frequency of the reconstruction of pointwise velocity, and (iii) the delays related to the operation of the extraction system. All these factors, and especially the last one, can hinder the correct performance of the controller, by introducing perturbations leading the system to unwanted oscillatory behavior, potentially disrupting smoke stratifications and delaying smoke extraction and intervention of firefighting squads. To this aim, in this work we propose a novel approach based on predictive control, aimed at improving the performance of the Mont Blanc Tunnel ventilation system. The method is based on an a priori analysis of the ventilation transients and asymptotic conditions for a wide range of scenarios, using both field data and a 1D numerical model. Results of the analysis are then used to construct corrective factors for the PID input signal. The constants for the corrected PID are then optimized using a DOE approach. Preliminary numerical assessments indicate a significant improvement of the system response and a drastic reduction of oscillations.
• Enhancements of tunnel ventilation system for road tunnels adopting aerodynamic control & monitoring strategiesCheung, Kelvin; Chan, Leo; Wan, Anthony; Lee, Hau Ming; 10.3217/978-3-99161-087-8-012Control of tunnel air quality during normal operation and control of smoke under fire emergency are two essential functions of tunnel ventilation system for road tunnels. Effectiveness of these two functions depends on many tunnel design elements such as tunnel alignment, cross-sectional geometry, traffic operations, location of ventilation shafts/plants, control strategy for ventilation and smoke in tunnel, etc. Semi-transverse ventilation strategy is a widely adopted scheme in many vehicular road tunnels worldwide due to its many advantages, in particular its comparative balanced effectiveness between performance of normal ventilation and that of emergency smoke control, over other schemes. There are several major aspects that can be further enhanced to provide a more cost-effective and safer tunnel environment for tunnel users. The paper aims to firstly identify the critical elements affecting the performance of tunnel ventilation system and to illustrate their potential implications to ventilation and smoke control. Secondly, study of feasible technical resolutions to cope with these effects are then introduced and supplemented with some practical examples of ventilation schemes for illustration. Moreover, further review using computer simulation analyses is also conducted for verification of the system performance from aerodynamic and thermodynamic points of view. Furthermore, the system design and implementation with real-time automatic system control and monitoring on relevant tunnel environmental elements are then illustrated including air quality monitoring system, airflow velocity, fire detection system, fire alarm system and associated mechanical/ electrical system design elements. Potential application of Internet-of-Things (IoT) and digital twin technologies for further enhancement of the system operation is also discussed. Last but not the least, the paper shares some case-studies including computer simulation analysis and testing results for tunnel projects to illustrate the practical implementation of these enhancements.
• Ventilation control optimisation for short longitudinally ventilated road tunnels in case of temporary bidirectional traffic operationHeger, Oliver; Schmölzer, Gregor; 10.3217/978-3-99161-087-8-013Maintenance closures in modern tunnel infrastructure often require temporary bidirectional operation of short, longitudinally ventilated road tunnels, creating significant challenges for ventilation control and fire safety. These tunnels, originally designed for unidirectional traffic, face increased risk during such phases, particularly when regulatory requirements cannot be fully met due to spatial and operational constraints. This paper examines optimization strategies for ventilation control under these conditions using a representative two-lane motorway tunnel as a case study. The Austrian TuRisMo risk assessment methodology was applied, combining quantitative scenario analysis with coupled 1D–3D smoke propagation modeling. A key focus was the impact of jet fan activation near fire locations, which can destroy smoke stratification and impair evacuation. To address this, an adapted modeling approach approximating jet fan-induced destratification was introduced. Results show that natural ventilation—deactivating jet fans in smoke-filled areas—can significantly reduce expected fatalities in certain scenarios compared to configurations involving temporary overblowing. However, controlled longitudinal ventilation remains advantageous in other cases. The findings highlight the need for flexible, risk-based approaches and performance-based design principles to balance safety, regulatory compliance, and operational feasibility during temporary bidirectional operation.
• External smoke movement and its impact on station design – Guidance for ventilation layoutThompson, Jolyon; Gilbey, Mark; 10.3217/978-3-99161-087-8-014Space or planning considerations can lead to the need to use pavement level grilles for forced smoke exhaust from metros. The emitted smoke might be ingested into station entrances or stair pressurisation system intakes which could impact the ability to evacuate the station. This challenge is not unique to underground stations - guidance on vent separation distance is available with building codes, but the quantities of smoke in metro application vents can be much higher than commercial buildings. There is very limited similar guidance on vent separation available to the design engineer for metros/stations. This paper explores the impact of smoke release at low level on key intakes for an assumed vent and entrance location for a simple station and urban configuration. It reviews a range of parameters which could impact upon the design and provides guidance on those which may be of importance. The paper also explores the benefits that an elevated release of smoke can offer so that the visual impact of an additional structure can be considered against the engineering consequences. The paper finally concludes with design advice that can be used during initial station layout. Whilst each station will have a wind microclimate that will affect smoke movement, some simple guidance as a starting point for laying out vents was considered as useful.
• Safety challenges of highway lids in the USPospisil, Petr; Santangelo, Colin; Hagenah, Bernd; 10.3217/978-3-99161-087-8-015Covering highways with lids creates space for recreation and urban development, reduces noise and pollution, and improves traffic safety, among other benefits. Urban highways are characterized by large traffic numbers on multiple lanes with regular congestion. While actual road tunnel safety knowledge is mostly derived from European tunnels with two or three lanes per tunnel cell, there are a few examples of modern urban highway tunnels with many lanes in each direction. Local driving habits and codes need to be considered alongside the laws and provisions in the US. Basis of design is a safety concept, describing safety systems and equipment in order of their effectiveness, prioritizing preventive measures. An Engineering Analysis for approval by the Authority Having Jurisdiction (AHJ) is required by the governing fire safety code NFPA 502. For that, we propose a Quantitative Risk Analysis (QRA), focusing on accident risks based on statistical data, and on fire risk based on simulations of smoke spread and egress for different scenarios under varying initial and boundary conditions. Statistical data about accidents and vehicles fires are available from the vast US road network. Tunnel specific European data and adapted to conditions in US high-way lids which differ from European tunnels. The appropriate simulation of different traffic scenarios is essential to understand the application of measures such as detection and traffic control, emergency exits, mechanical ventilation and Fixed Fire Fighting Systems. This paper describes a holistic approach to tunnel safety by providing a methodology for developing safety concepts and QRA with focus on tunnel ventilation aspects.
• Cultural differences in road tunnel fire safetyStacey, Conrad; Beyer, Michael; 10.3217/978-3-99161-087-8-016In these days of easy international travel, the world seems to be becoming more homogenous. You can get good sushi in Graz and Brisbane, good steak in Osaka and Graz, and schnitzel everywhere including Osaka and Brisbane. Why then are our approaches to tunnel fire safety so different? For real cultural experiences when you travel, forget the food – go and look at the tunnels. This paper notes differences in approaches to ventilation, fire suppression and tunnel operation and, within the limits of our knowledge, tries to rationalise them. Simply thinking about the differences may assist advancements in any of the jurisdictions, perhaps in a direction not identical to any of them.
• The best thing FEDRO has provided us within recent years! Experience from over 50 operational concepts for Swiss road tunnelsWetzel, Ralf; Jäger, Christian; 10.3217/978-3-99161-087-8-017After a fire, various defects are discovered in the operating and safety equipment (OSE) of a tunnel! A truck enters a tunnel with an extended crane and damages the OSE in the entrance area! The system control of the tunnel ventilation fails! What to do? In Switzerland, Regional Units (RU) are responsible for operating the national road tunnels. They are regularly confronted with these or similar issues. The options for further action are many: tunnel closure, tube closure, lane reduction, operation under minimum requirements or normal operation with/without measures. Other questions also arise: Act immediately or later? Who should be informed? Who decides? The operating concepts (OC) for road tunnels enable the RU to correctly assess the situation in the event of system failures or external events (accident, fire, …), make quick decisions and involve the right people. This ensures the safety of road users and maximizes the availability of high-performance roads. RU and planners can use the OC to optimize spare parts inventory. Components with long permissible downtimes do not need to be procured as spare parts. Components with short permissible downtimes or components whose failure would lead to operation under minimum conditions or to a tunnel closure must be available quickly and kept in stock as spare parts. OC developed during the planning phase enables the planner to align his concepts at an early stage to clarify the availability and safety requirements of the project and agree them with the client. These include redundancy concepts, failure strategies and refurbishment concepts. This article will share the experience of IG BeSt (ILF Beratende Ingenieure AG / WSP Ingenieure AG) from over 50 implemented OC and answer the question of why a RU employee describes them as the best that Federal Roads Office (FEDRO) has provided to RU in recent years.
• Thrust comparison of conventional jet fans and fans with shaped silencers in an Italian road tunnel based on In-Situ measurementsTarada, Fathi; Stantero, Luca; Bertacche, Pier; Boffa, Natalino Daniele; Bezzi, Francesco; Lucatelli, Natalino; 10.3217/978-3-99161-087-8-018This paper presents the results of an extensive in-situ measurement campaign aimed at quantifying the performance of conventional jet fans and using fans with shaped silencers. The tests were conducted at the Verta Tunnel, an existing 3.5 km long road tunnel with an arched cross-section operated by the Italian road authority (ANAS). A detailed velocity grid measurement was undertaken within the tunnel, capturing the airflow profile across the entire cross-section. This measurement allowed for an evaluation of the flow distribution resulting from fan operation, as well as a calculation of the effective thrust generated by the two different jet fan types. Additional parameters, such as pressure differentials, were recorded at strategic locations to support the overall analysis. The results demonstrate differences in thrust and flow development between conventional jet fans and those with shaped silencers. The findings not only provide insight into the in-tunnel thrust of each jet fan type, but also highlight the impact of tunnel geometry and installation layout on the actual ventilation performance.
• Optimization of the main fans and associated drives for the E4 Stockholm bypassBrandt, Rune; Stevelink, Peter; 10.3217/978-3-99161-087-8-019The Stockholm Bypass project is part of the European motorway E4 and will connect the southern and northern regions of the Stockholm County. The Bypass is 21 km long, of which 18 km are in tunnels. The ventilation system of the unidirectional tunnel consists of 241 jet fans (124 x 1000 N and 117 x 1500 N) and 47 main axial fans rated at 200 m³/s, installed in 17 ventilation stations. Minimising environmental impact is a key objective of the Swedish Transport Administration (Trafikverket). The total installed fan power amounts to 27 MW (17 MW for the main axial fans and 10 MW for the jet fans). Optimising fan and drive efficiency as well as minimising flow losses are therefore essential. Eighteen of the 47 main axial fans must provide 120 m³/s in reverse-flow mode (60% reversibility), while the remaining 29 are operated only in forward direction. Pressure losses and ventilation regimes vary among the 17 ventilation stations. For system-redundancy reasons, all 47 motor-impeller units are required to be identical. The paper discusses: design requirements for the axial fans and the resulting main design parameters; duty points for the ventilation stations and for the axial fans; evaluation of three variable-speed configurations (A: variable speed drive (VSD), B: two-speed 50% / 100 % (6/12-pole), and C: two-speed 75% / 100 % (6/8-pole); analysis of the performance of ventilation stations operating at 20 % to 100 % capacity; evaluation for five typical operating scenarios to determine the most energy-efficient configuration. The study concludes that the intended configuration i.e. axial fans with variable pitch in motion combined with variable speed drives offers the highest overall energy efficiency. Only in one scenario is variant C marginally more efficient.
• Experimental investigation of thermal runaway in lithium-ion batteries: Implications for tunnel safety and structural integrityPapurello, Davide; Musso, Luca; Barbetta, Carlo; Borchiellini, Romano; Sobótka, Maciej; Fruhwirt, Daniel; 10.3217/978-3-99161-087-8-020The increasing use of lithium-ion batteries (LIBs) in electric vehicles and energy storage systems raises new safety concerns, particularly in confined environments such as road tunnels. This study presents an experimental investigation into thermal runaway (TR) events in LIBs triggered by mechanical, thermal, and electrical abuse conditions. The work focuses on characterising temperature and pressure evolution, gas emissions, and the effects of battery fires on surrounding structural materials, specifically concrete, representative of tunnel linings. Abuse tests, including nail penetration, overheating, and external short circuits, were conducted using an Accelerating Rate Calorimeter (ARC). The maximum temperature, pressure and released gases were monitored. Pre- and post-mortem computed tomography analyses provided insight into internal cell degradation and structural changes. Importantly, TR events in proximity to cement mortar samples revealed their thermal damage, leading to microstructure degradation (mostly microcrack network development) after repeated exposure. The results show that thermal runaway of cells can rapidly propagate in confined spaces, developing flammable gases, toxic substances and thermal loads capable of compromising tunnel structures. Cells triggered at higher ambient temperatures are more reactive, reaching higher peak temperatures and pressures during TR. The state of health (SOH) of cells influences the severity of TR, with degraded cells producing less intense but still dangerous reactions. Overheating tests demonstrated a critical delay window (~350 s) enabled by safety valve activation, crucial for mitigation in real tunnel scenarios. For external short circuit, no thermal runaway occurred for different SOC states. These findings contribute to a better understanding of LIB behaviour under critical conditions and support the development of safety strategies, emergency response plans, and structural containment systems for tunnels. The data will serve as a basis for future risk assessments and engineering models aimed at improving resilience to battery-induced fires in underground infrastructure.
• Smart tunnel in industry 5.0: Improving road tunnel resilience by dynamic risk analysisFocaracci, Alessandro; Zacchei, Francesca; Martirano, Luigi; 10.3217/978-3-99161-087-8-021Safety in tunnels is being contemplated through a holistic approach due to accidents that occurred through years. Technological innovations have led to the tunnel concept evolution from civil to technological infrastructure, where technology overcomes the limits of the geometric design, increasing its operating capacity. This paper aims to illustrate SCADRA principles (Supervisory Control Acquisition and Dynamic Risk Analysis), developed thanks to EURAM (EUropean Risk Analysis Method) methodology, which assessed the risk of over 600 road tunnel tubes, focusing on the following values: users and managers' needs (Human-centricity), usage of green technologies and application of energy saving strategy (Sustainability), and improvement of tunnels resilience (Resilience). SCADRA is used in monitoring continuously the tunnel state by gathering the safety influence variables and performing a dynamic risk analysis, quantitative and probabilistic, in real-time. The system was installed in three Italian road tunnels, executing over 130,000 instantaneous risk analyses. The applications’ results and the future developments will be presented according to tunnels’ safety improvement, maintenance, and management.
• Acceptance criteria for design of longitudinal ventilation systems in road tunnels: Theoretical frameworkPachera, Matteo; Chaudhary, Ranjit; Van Nerom, Jef; Vernieuwe, Stefaan; 10.3217/978-3-99161-087-8-022This paper investigates the relationship between fire risk and tunnel ventilation and its integration into the ventilation design process. Longitudinal ventilation is commonly applied in road tunnels with unidirectional traffic, as it confines smoke downstream of the fire and protects road users upstream of the incident. The risk of fatalities among road users in case of fire is primarily associated with the potential smoke propagation and exposure of road users. In addition, elevated temperatures during tunnel fires may cause damage to structural and electro-mechanical components, resulting in economic losses. Both life safety and economic risks are related to the installed ventilation capacity and to air velocity in the tunnel for different fire sizes, fire locations and wind conditions. Two formulations are derived to quantify the equivalent risk indicators for road users and for the structural damage. These indicators are expressed as functions of tunnel geometry, traffic intensity, and traffic composition, enabling specific risk evaluation for each tunnel. The proposed indicators are then applied to a case study in which the same tunnel is analysed under different traffic conditions. The results show that the tunnel ventilation design should not be based solely on critical velocity evaluation; but it should also consider other factors such as traffic conditions and tunnel connectivity. A comprehensive design should address both the risk associated with road user safety and with the business continuity in the event of a fire.
• State of the art and lines of development for the ARTU risk analysis softwareScozzari, Rugiada; Fronterrè, Michele; 10.3217/978-3-99161-087-8-023ARTU, acronym for “Risk Analysis in Tunnels”, determines the societal risk related to fire in road tunnels and calculates the FN-curve accordingly to the European Directive 2004/54/EC. ARTU performs a quantitative assessment of risk, coupling probabilistic Monte-Carlo and deterministic approach. In the last years, some updates were made in order to make ARTU suitable to address a wider range of tunnel typologies. As an example, a multi-scale approach to fluid-dynamics has been included, based on a zone model developed by Lund University, called MZ. At the same time, many efforts were put in assuring that ARTU results are reliable. Fire tests have been performed at the Lund University scale tunnel facility to validate the software and study the applicability limits. Based on these results, a methodology has been drawn up to identify the cases in which ARTU gives satisfactory results and cases in which further analysis are needed. Regarding the smoke dynamic, the use of the 1D model introduces some errors in particular for what concerns the presence of stratification and back-layering. These errors are partially corrected by the multi-scale approach but could have a relevant effect in the risk estimation for tunnels with specific characteristics as the absence of mechanical ventilation or bidirectional traffic. In these case, further analysis, as CFD simulations, could be needed to obtain robust and appropriately conservative results. The methodology aims at a systematically classification of tunnels and procedure to be followed to properly assess the risk. The present paper discusses the above mentioned methodology in the framework of existing risk analysis methods. The paper also includes an overview of main road tunnel risk analysis developed by ARTU. This allows to clarify the ARTU applicability limits, strong points and possible future developments.
• Heat transmission between ground and tunnel air for different configurations and usesSanz Sacristán, Juan Manuel; 10.3217/978-3-99161-087-8-024From exhaustive measurements of the temperature variation in different positions of different tunnels, the phenomena of heat transmission between ground and air are explained for different configurations, depths and uses of the infrastructure. The tunnels for which temperature data are available over time at different points and for which the processes of heat exchange between ground and air are analysed based on their comparison with the outside temperatures and air velocities inside are: urban tunnel of great extension and complexity (M30), metro line (L1 Metro de Barcelona) and 24 km long mountain railway tunnel (in its stage prior to operation). This data is complemented by calibrated 1D CFD simulation models of these infrastructures that allow for a deeper analysis of these phenomena and additional situations that have not occurred. From these analyses we can conclude that the transmission of heat between the ground and the tunnel is a phenomenon of great importance to obtain in the design stage the evolution of the temperature over time and its variation between winter and summer. These conditions can imply natural currents due to the chimney effect at certain times of the year or cyclical currents throughout the day and that in the tunnels in operation can be masked by the piston effect. As an example, on the M30 every night there are important natural currents in a fixed direction at each point even though traffic is very low and that even in many areas it is contrary to the direction of traffic. This phenomenon occurs in the same direction and similar values throughout the year and it has been proven that its reason is that at night the temperature in the tunnel is close to the average day and it is higher than the lower temperatures of the night, which causes chimney effects between portals of different heights due to air density variations. Heat transmission is also quantified according to the depth of the tunnel and connection points with the outside. This allows to calculate the transition distances between the outside and the ground temperature.
• Enhancement of the dispersion of pollutants near a tunnel ending in a street canyon, a CFD case studyRemion, Gabriel; Vidal, Bruno; Kubwimana, Thierry; Yaghzar, Marouane; Mos, Antoine; Boissat, Romain; Revelat, Edwige; Stepanian, Alexis; 10.3217/978-3-99161-087-8-025Covered expressways have several advantages in terms of quality of living inside cities. However, they concentrate pollutants at their portals, which are often located in street canyons. The configuration of these street canyons, which are often below the street level, hinders the wind inflow. This can result in the stagnation of pollutants and the exposure of people living or working in their vicinity. A mitigation solution has been assessed in order to enhance the dispersion of pollution, and thus, reduce the exposure risk. Urban tunnels are usually equipped with a ventilation system that dilutes pollutants to comply with regulatory thresholds. The idea of the mitigation solution is to additionally control the ventilation system using NO2 sensors located outside of the tunnel. This article first aims at characterizing the exposure risk around the street canyon, and then at testing the influence of the proposed mitigation solution. A Reynolds-Averaged Navier-Stokes model of a real field case with two tunnels ending in an cut street canyon in Marseille, France, was implemented. The topography, the thermal stability of the atmosphere, and buildings were modelled. An experimental campaign was also conducted to validate the model. Both the experimental campaign and the CFD model demonstrated the sensitivity of the site in terms of air quality. The risk of exceeding the hourly NO2 regulatory threshold at the ground level, and on building facades, was ascertained. The proposed mitigation solution was found to be highly effective in reducing the exposure risk for people living or working near the street canyon.
• Smoke recirculation at road-tunnel portalsBettelini, Marco; Tobler, Marco; Defert, Raphaël; 10.3217/978-3-99161-087-8-026In case of fire in twin-tube tunnel systems, the parallel tube is commonly used as a haven for self-rescue and plays an essential role for intervention. This requires a high level of protection against smoke penetration through cross connections and tunnel portals. Structural (e.g. shifting of portals or anti-recirculation walls) and technical measures (primarily appropriate ventilation control) are commonly adopted for preventing portal recirculation. Anti-recirculation walls are frequently unwanted, mainly because of their visual and operational impact as well as cost. Project-related detailed investigations showed that the benefits from anti-recirculation walls are at times lower than expected. This paper provides guidance for screening and detailed assessment of requirements and benefits. Appropriate numerical simulations can help to avoid large structural measures with low effectiveness.
• Application of low-tech and lean-tech concepts to road tunnels for greater energy efficiencyRegnier, Tristan; Martinetto, Olivier; Guiral, Florent; 10.3217/978-3-99161-087-8-027Our planet is facing a major climatic challenge, which is becoming increasingly acute and critical. The need for underground communications infrastructure, to be maintained or created, remains strong in all countries to meet the needs of trade, travel and development. These infrastructures can be money pits with a high carbon footprint. Simply optimising a system, is not enough to meet the challenges. The usual reliance on technology and the development of new systems in the hope of reducing the energy balance, while relevant in some cases, can be a headlong rush or an illusion with no guarantee of overall savings. In this context, a different, holistic approach seems necessary in terms of design, operation and maintenance, and even use. The entire life cycle of the structure is concerned, particularly the design and operation phases: The design phase is totally structuring even if it is one of the shortest. It obviously involves a series of technical choices dictated by regulatory requirements, but which must also meet the specific constraints of operation and maintenance and the level of service expected of the structure, a level that is often poorly defined. It also deals with the criteria for choosing and procuring supplies, which are often neglected for lack of a suitable analysis tool. The operating phase, which is intended to be as long as possible, is crucial. Beyond the ‘established regime’, this phase includes major maintenance and renewal stages that must be taken into account right from the design stage. This article looks at the practical implementation and convergence of different approaches: Low-Tech: using solutions technologically “sober” in terms of natural resources and energy consumption. Lean-Tech: using technology as “leanly” as possible. Design for Maintenance (DfM): maintenance/maintainability-oriented design. Reliability Maintainability Availability Safety (RAMS) of “systems”.
• Effects of contributing to decarbonization by model-based predictive ventilation control (MPVC) on expresswaysUeda, Hiroki; Ichikawa, Atsushi; Yuhara, Minoru; Hiro, Masaki; Fujita, Yuichiro; Takahashi, Wataru; Vardy, Alan; 10.3217/978-3-99161-087-8-028Although the scale of ventilation in highway tunnels has been decreasing due to stricter exhaust gas regulations, normal ventilation is still required under special conditions, such as long tunnels with two-way traffic and tunnels that require environmental measures at the portal. Historically, achieving stable, effective ventilation control in such complex tunnels without wasteful power consumption has been an issue. To address this, the NEXCO Research Institute and NEXCO companies have introduced the tunnel ventilation control software MPVC, which performs optimal control Based on a survey of the operational status of tunnels where MPVC has been introduced, this paper evaluates the optimization of control and the effect of reducing power consumption, and clarifies the contribution to decarbonization, future issues, and prospects.
• Improving energy efficiency in road tunnelsKirchebner, Lorenz; Wierer, Alexander; Sistenich, Christof; Bacher, Michael; Hinterhofer, Marlene; Marcher, Thomas; Kaml, Georg; 10.3217/978-3-99161-087-8-029The operation of road tunnels leads to considerable energy costs, which are expected to increase further due to the rising energy prices and stricter climate policies. This elaboration highlights technical, operation and planning-based approaches to reduce energy demand and life-cycle costs, based on the findings of the BASt research project “Ermittlung und Bewertung zur Steigerung der Energieeffizienz”. Energy consumption data from more than 35 road tunnels have been analyzed, revealing that lighting accounts for the largest share – 50 % to 60 % – of the total energy demand, consistent with findings across the DACH region (Germany, Austria and Switzerland). Based on these insights, the project identifies three main pillars for energy optimization: Energy sources near or within the tunnel: integration of renewable energy systems, such as photovoltaic panels, hydropower from drainage systems and electricity generation from natural airflows. Energy saving measures: implementation of energy-efficient components and design strategies, including optimized tunnel portals, high-reflectivity road surfaces and daylight-introducing elements like entrance light shafts. Operation strategies: improves system control and regular maintenance, such as adaptive lighting control, demand-based ventilation control and implementation of energy monitoring with benchmark integration Beyond technical measures a methodical framework for assessing tunnel energy performance as a basis for systematic energy management is developed. These results contribute to the development of a practical planning tool that supports sustainable tunnel operation and energy-efficient infrastructure design.
• On smoke detection systems in road tunnels – a quantitative comparisonGehrig, Samuel; Frey, Simon; Pollinger, Benjamin; Buchmann, Reto; Crausaz, Bernard; 10.3217/978-3-99161-087-8-030Reliable incident detection is crucial for safety and operation of road tunnels. On the one hand, rapid and accurate detection of incidents allows for timely activation of electromechanical equipment such as tunnel closure or ventilation systems. On the other hand, high reliability or low false alarm rates is a prerequisite for daily operations and user satisfaction. In Swiss road tunnels, smoke sensors based on visibility measurement have been in use for nearly 20 years. Combined with an evaluation logic to distinguish between moving and stationary smoke sources, this has become an established solution. Nevertheless, continuous optimisation and development is being performed regarding sensor technology, sensor placement as well as evaluation logic. Video based Automatic Incident Detection (V-AID) is only sporadically used for fire detection, primarily due to the perceived lack of quality and reliability. As part of a general study on smoke detection in road tunnels, the performance of conventional smoke detection and of modern V-AID systems is quantitatively compared, based on a large number of smoke tests. The tests include both moving and stationary smoke sources as well as different longitudinal airflows (intensity and direction). Each test was performed at least 3 times to account for variations. The performance of both systems is evaluated and compared using various parameters and, in particular, a dimensionless number accounting for the spatial and temporal sequence of smoke detection. The work shows promising results using V-AID regarding the detection quality but also reveals a certain number of points to be addressed, prior to a wide use of modern V-AID systems for smoke detection.
• Ventilation system upgrade for Huguenot tunnel in South AfricaMassingue, Tiago; Kearns, Julia; 10.3217/978-3-99161-087-8-031Worldwide, tunnel operators increasingly adopt modern ventilation technologies to enhance safety and operational standards. This is the case for ventilation systems in the Huguenot Tunnel, South Africa, where the current ventilation system that has been in operation since 1982, is now inadequate and subject to immediate replacement. The major drive for this effort is that the existing system, built in the 80s, no longer meets the requirements of a modern tunnel. A single 375 KVA axial fan in each 4km bore for both air inlet and extraction partnered with one for extraction at the portal of each bore cannot respond to the 100 MW fire load requirement. The two axial fans are located exactly at the ceiling portal at less than 5 m from the entry. 'While ventilation alone cannot fully mitigate fire risks, modern localized solutions significantly improve tunnel safety.
• Web-SCADA: A web-based supervisory control and data acquisition platform for road tunnel safety in JapanDickel, Leon; Ruffieux, Mathis; Rouge, Jean; Lai, Yen-Hung; Nakamura, Masahide; Vardy, Alan; 10.3217/978-3-99161-087-8-032The proposed paper introduces a web-based, remote-access platform for tunnel supervisory control and data acquisition (“SCADA”). The system enables operators and emergency services to monitor safety systems (e.g. fire detection and location) and ventilation systems, and to activate desired responses. The platform consists of an operational technology (OT) layer where real-time data is collected in a conventional database, and an information technology (IT) layer where web-based technology has replaced conventional display methods on monitoring screens. We propose a Web-SCADA architecture built on the latest web technology. It is designed to support ubiquitous monitoring, with data displayed not only on conventional PC screens at the control centre, but also on tablets and smartphone screens in the office or even at home. By enabling direct access to the data in this way, the system facilitates fast responses by the police and fire services as well as by tunnel controllers. Also, by ensuring that everyone has access to the same up-to-date information, it enhances both the speed and reliability of information transfer, frees up humans for other tasks, and reduces the risk of potentially-flawed human communication. Simulation-based modelling is integrated into the web-SCADA to extend the real-time modelling with forecasts of the potential development of conditions (e.g. fire and smoke propagation). The modelling also assists in the detection of potential failures of sensors and other equipment. Overall, the platform represents a significant enhancement of tunnel management whilst simultaneously reducing the need for human resources (a particular concern in Japan). It is expected to enhance both safety and operational efficiency.
• Towards accurate tunnel fire simulations: Grid sensitivity and les model comparison in fire dynamics simulatorSarwar, Mahfuz; Moinuddin, K.A.M.; 10.3217/978-3-99161-087-8-033This study examines the grid sensitivity of four Large Eddy Simulation (LES) sub-grid scale (SGS) turbulence models available in Fire Dynamics Simulator (FDS) namely the Standard Smagorinsky, Dynamic Smagorinsky, Deardorff, and Vreman models using a backward-facing step benchmark. Results show that grid resolution has a stronger influence on LES performance than the choice of SGS model, highlighting the inherent challenge of achieving grid-independent solutions in implicitly filtered LES. Among the models assessed, the Standard Smagorinsky model exhibits the most consistent convergence behaviour and produces the closest agreement with experimental data, even though full grid convergence remains elusive. Additional refinement confirms that FDS’s second-order scheme can deliver acceptable accuracy when sufficiently fine meshes are used. These outcomes are directly relevant to tunnel CFD fire simulations, where accurate prediction of smoke movement, temperature distribution, and fire-induced flow fields is critical for occupant safety, ventilation design, and regulatory compliance. By providing a detailed understanding of SGS model behaviour and grid sensitivity, this study highlights the importance of carefully designed mesh strategies and informed SGS selection particularly the Standard Smagorinsky model, which exhibits the strongest convergence tendencies for reducing modelling uncertainty. The insights gained from this work enable more reliable simulation of flow separation, recirculation, and smoke stratification, thereby enhancing the robustness and credibility of FDS-based tunnel fire assessments and supporting better-informed engineering decisions and performance-based design approvals.
• On the flow resistance of tunnel fires – validation by full-scale fire testsRiess, Ingo; Deb, Rajdeep; Weber, Alex; 10.3217/978-3-99161-087-8-034The aerodynamic resistance of a tunnel fire in longitudinal ventilation, also known as “throttling effect”, is relevant for the design and operation of longitudinal tunnel ventilation systems. The throttling effect has been investigated in an extensive CFD study, as presented at the Tunnel Safety Conference in 2020 [1]. It was found that the temperature and airflow stratification downstream of the fire contributes to the pressure drop even far beyond the extent of the fire. A 1-D model of various factors contributing to the air-flow resistance of a tunnel fire has been presented. In June 2024, we performed full scale fire tests in the test facility at the “San Pedro des Anes” Experimental Centre in Spain. The test facility allows controlled fires with a heat release rate up to 10 MW, jet-fan induced longitudinal flow and sufficient distance from the downstream portal to investigate temperature stratification. The experimental setup allowed direct pressure measurements between the tunnel and a parallel service gallery. Still, the observed pressure differentials were small and external meteorological pressures influenced the measurements in some of the tests. It was not possible to validate the increased pressure drop downstream of the fire that was observed in the CFD simulations of the 2020 study. In this paper, an updated 1-D model for the throttling effect is presented that is supported by experimental data and by improved CFD modelling. Furthermore, a frequency analysis of the static pressure has been performed with the goal of comparing the observed frequencies to the characteristic frequencies of the fire source and of the tunnel.
• Effect of road tunnel fitout on smoke controlBeyer, Michael; Stacey, Conrad; 10.3217/978-3-99161-087-8-035A CFD model, previously validated against the Memorial Tunnel fire tests with longitudinal ventilation, is used to investigate the influence of ceiling-mounted road tunnel equipment on upstream smoke propagation in case of a road tunnel fire. Typical road tunnel installations, including cable trays, hangers, lighting, signage, misting pipes, speakers, etc. were incorporated into a representative three-lane TBM tunnel geometry and compared with an otherwise identical tunnel without ceiling obstructions. The study examines differences in smoke behaviour for both the critical velocity case, defined by the prevention of upstream backlayering, and the confinement velocity case, defined by limiting the upstream backlayering length to 30 m. The observed differences are interesting as the tunnel equipment does not materially alter critical velocity required to prevent backlayering. However, for the confinement velocity case, the presence of ceiling obstructions significantly affects upstream smoke propagation, resulting in increased backlayering lengths for the same applied ventilation flow rate. The results are configuration-specific and reinforce the need for project-specific, validated CFD assessments when determining confinement velocity in tunnels with obstructed ceiling spaces.
• Consequences from large EV fires in tunnels - a DACH research activitiyFruhwirt, Daniel; Kores, Alexander; Galler, Robert; Wenighofer, Robert; Lotmann, Bastiaan; Frey, Simon; Thienert, Christian; Leismann, Frank; Schneider, Christoph; 10.3217/978-3-99161-087-8-036In recent years, battery-electric vehicles have reached a significant market share. Although this statement mainly refers to passenger car applications, meanwhile e-mobility has also reached heavy duty vehicles and buses. Many research activities have been conducted in order to evaluate the fire characteristics and the hazards posed by EVs. Available data from full-scale testing of small BEVs show no significant increase of risk compared to fires of conventional vehicles. However, there is only little information available about the fire risk of large EVs. For this reason, the DACH research area has initiated a dedicated research project in order to evaluate the fire characteristics of battery-electric trucks and its consequences for road tunnel safety. A key element of the DACH research activity is to perform a full-scale fire test of an EV truck in a road tunnel environment. Thereby, assessing both the consequences for tunnel users and the tunnel structure. This paper provides a comparative overview of today´s EV landscape and an introduction to the eTRUCK-DACH project.
• Modelling airborne brake wear particle transport in subway systems: A line-scale frameworkHerrero, Rodrigo; Sánchez, Carla; Rodríguez, Laura; 10.3217/978-3-99161-087-8-037Subway systems present specific challenges for indoor air quality and associated health risks. Stations, platforms and tunnels constitute enclosed or semi‑enclosed environments characterized by complex airflow patterns. This paper proposes a one‑dimensional advection–diffusion transport model to represent the evolution of pollutants generated by mechanical braking along an entire subway line (Line 1 in Metro de Madrid). The formulation incorporates source terms, deposition (sink) mechanisms, detailed station and track geometry, the real dynamics of moving trains, the configuration of ventilation shafts, and time‑dependent forced‑ventilation operating schedules. The model makes it possible to proportionally quantify the spatial and temporal distribution of pollutant emissions resulting from the different mass‑transport mechanisms involved in this environment, and it also enables the prediction of accumulated total values under various operating conditions. This framework enables comparative evaluation of different mitigation strategies aimed at reducing the impact of particulate emissions on air quality, with particular emphasis on assessing on board retrofit filtration systems designed by Tallano technologies to reduce pollutant mechanical brake generation at the source, beyond the conventional strategies of ventilation control and cleaning programs.
• From motion to understanding: How deep learning enhances automatic incident detectionMarchand, Emmanuel; Sekula, Maciej; Colombel, Christophe; 10.3217/978-3-99161-087-8-038Automatic Incident Detection (AID) through video analytics is a cornerstone of modern traffic management. Historically, AID systems relied on pixel-based algorithms, detecting incidents by analysing changes in pixel intensity and movement over time. While foundational, these traditional methods often struggle with environmental noise and static scenes, leading to missed incidents and high false alarm frequencies. This presentation by Citilog explores the paradigm shift brought by Deep Learning (DL) in AID. Unlike pixel-based methods that track abstract motion, DL models are trained for true object recognition and scene understanding. We will demonstrate how this transition fundamentally improves detection quality – simultaneously increasing true detection rates and drastically decreasing false alarms – through three key examples: Stopped Vehicle Detection: Traditional pixel-based systems frequently trigger false alarms from moving shadows or sudden lighting changes. Deep Learning accurately distinguishes between a cast shadow and an actual stationary vehicle, ensuring high reliability. Pedestrian Detection: Legacy analytics typically require tracking a small group of pixels over a long trajectory to confidently identify a pedestrian. In contrast, Deep Learning can recognize a human form instantly within a single frame, enabling much faster and more accurate detection. Smoke Detection: Pixel-based methods are largely limited to detecting a general loss of visibility by comparing the current scene against historical reference images. This requires time to establish a baseline and often cannot confirm if the visibility drop is actually smoke. Deep Learning, however, can instantly recognize the unique visual structure and patterns of smoke within a single frame, resulting in significantly faster and more precise alerts. Deep Learning participates to define a new standard for AID accuracy, paving the way for safer, more efficient, and highly responsive road networks.
• Influence of the tunnel cross-section on tunnel aerodynamicsLangner, Verena; Huber, Andreas; Rodler, Johannes; 10.3217/978-3-99161-087-8-039In addition to technical aspects, financial considerations also play a role in the planning of a railway tunnel. Since the tunnel shell accounts for a significant portion of the construction costs, efforts are made to keep the excavated volume as small as possible. This often results in very small tunnel cross-sections, which, in combination with high train speeds, lead to pressure changes with high amplitudes. The loads caused by the pressure changes generally represent the design reference for the load limit of trains and the components installed in railway tunnels. It has been shown that some of the cost savings in shell construction are offset by increased expenditure on tunnel equipment. In addition, small cross-sections can cause the problem of a so-called “sonic boom”, which can only be solved by additional construction work. This article aims to highlight the connection between tunnel cross-sections and the associated aerodynamic aspects and to raise awareness of the importance of careful coordination of construction planning with regard to these aspects.
• Air speeds near services on tunnel wallsGilbey, Mark; Ajewole, Dami; Soper, David; Jesson, Mike; Strudwick, Ian; 10.3217/978-3-99161-087-8-040Tunnel services can be exposed to pressures and airflows that subject them and their supports to fatigue loads. The fatigue loads can be significant in high-speed tunnels. Pressure changes from train movements in tunnels are well covered by available modelling techniques, and for services completely immersed in the pressure these changes do not often form the design cases. Air speeds in train wakes are less well predicted by numerical modelling, specifically the range and scale of the 3-D velocity fluctuations generated by their highly turbulent nature. This paper describes testing of moving trains in 1/25th scale tunnels. Model trains were fired at high-speed into the scale model tunnels and the tunnel air speeds near the walls measured at high frequency in three directions and at several locations. Different diameter tunnels and train designs and consists were tested. The data from the testing was interpreted using rainflow counting to estimate fatigue loads for discrete (small) items of equipment in the tunnels as well as longer elements where the wake velocity may affect the equipment in different ways.
• Train-induced aerodynamic loads acting on installations of Granitztal tunnelReiterer, Michael; 10.3217/978-3-99161-087-8-041In railway tunnels, highly dynamic pressure waves and flow-induced aerodynamic loads occur during train entry, passage, and exit. These loads act on all tunnel installations and must be considered in the design of the structural elements installed in tunnels. Due to the high number of daily train journeys and the associated high number of load cycles over the entire service life of the structural elements in tunnels, fatigue analyses, in addition to verifications of structural safety, are particularly important. During the planning phase, aerodynamic load assumptions were defined for the different installations in the Granitztal Tunnel, and these assumptions formed the basis for the design. The definition of these load assumptions was based on existing standards and regulations, as well as numerical simulation calculations and/or measurements of train-induced aerodynamic effects in comparable railway tunnels in Austria. During the commissioning runs of the Koralm railway line in 2025, the actual aerodynamic loads occurring during train journeys in the Granitztal Tunnel were measured and compared with the load assumptions defined for the design. This article describes and discusses the measurements carried out in the Granitztal Tunnel and the results obtained. It demonstrates that the aerodynamic load assumptions defined during the planning phase for the various tunnel installations are conservative, thus ensuring both the load-bearing capacity and fatigue resistance of the structures over their entire service life.