Vehicles In Tunnel Research Articles

Assessment of vehicle exhaust PM emissions using high-resolution on-road measurements in Seoul, Korea

In megacities, road traffic is a major source of particulate matter (PM), requiring a critical understanding of effective air pollution control. Despite existing methods to determine PM emission factors (EFs) of vehicles, accurate estimation of PM emissions under real driving conditions remains challenging. We aimed to assess the EFs of organic aerosol (OA) and equivalent black carbon (eBC) from vehicles through on-road measurements in Seoul, Korea, to understand real-world PM emissions. We used a mobile laboratory equipped with an aerosol mass spectrometer and an aethalometer to measure the composition of PM. On-road measurements were conducted in vehicle tunnels, urban roadways, and residential areas, and the characteristics of measurement points were compared and analyzed. Our results showed that concentrations of OA increased proportionally with the influence of vehicle exhaust, while oxidation states of the OA decreased. Mobile measurements revealed spatial heterogeneities in aerosols, highlighting distinct characteristics of fresh OA on vehicle roads and elevated oxidation state values in residential areas. Active nitrate formation near vehicles led to elevated NO3 concentrations on roads compared to residential areas. Our study shows that mobile PM measurements, including OA and eBC, are valuable for the direct evaluation of emission inventories. However, given that the calculated EFs may not be applicable to other cities due to differences in vehicle composition and traffic conditions, the development of city-specific EFs will be necessary in the future. Furthermore, it is recommended to integrate this methodology with conventional emission inventories to identify vehicle-type-specific emissions.Graphical

Research on construction and environmental impacts of a large-diameter pipe jacked along curve underwater

The pipe jacking method is widely used in water supply and drainage, power tunnels, vehicle tunnel construction, and other fields. The main challenges include friction resistance, axis deviation, and environmental disturbance, especially when large-diameter pipes are jacked along the curve underwater. Based on a large-diameter pipe jacking project under Jinshan Lake, this paper records the settlement of surrounding structures, the jacking force, and the deviation in the axis and elevation during the jacking process. Furthermore, the factors affecting the monitoring data under different working conditions are studied, and the key points are concluded. The outcomes of the study will provide a reference and serve as a guidance for future related projects.

Fluid–Vehicle–Tunnel Coupled Vibration Analysis of a Submerged Floating Tunnel Based on a Wake Oscillator Model

Abstract The submerged floating tunnel (SFT) is a newly developed traffic structure for crossing the long waterway. On the basis of the vehicle–tunnel coupled vibration, the vortex-induced effect o...

Theoretical, Numerical, and Experimental Study on the Identification of Subway Tunnel Structural Damage Based on the Moving Train Dynamic Response.

As an important part of urban rail transit, subway tunnels play an important role in alleviating traffic pressure in mega-cities. Identifying and locating damage to the tunnel structure as early as possible has important practical significance for maintaining the long-term safe operation of subway tunnels. Summarizing the current status and shortcomings of the structural health monitoring of subway tunnels, a very economical and effective monitoring program is proposed, which is to use the train vibration response to identify and locate the damage of the tunnel structure. Firstly, the control equation of vehicle–tunnel coupling vibration is established and its analytical solution is given as the theoretical basis of this paper. Then, a damage index based on the cumulative sum of wavelet packet energy change rate (TDISC) is proposed, and its process algorithm is given. Through the joint simulation of VI-Rail and ANSYS, a refined 3D train-tunnel coupled vibration model is established. In this model, different combined conditions of single damage and double damage verify the validity of the damage index. The effectiveness of this damage index was further verified through model tests, and the influence of vehicle speed and load on the algorithm was discussed. Numerical simulation and experimental results show that the TDISC can effectively locate the damage of the tunnel structure and has good robustness.

NUMERICAL INVESTIGATION ON SMOKE MANAGEMENT IN UNDERGROUND BRANCHED TUNNELS

Soot is perhaps the most harmful element in vehicle tunnels fire as smoke moves harmonize with the way passengers flee. It decreases visibility and can cause suffocation fatalities.
 This paper presents an empirical analysis on the effect of removing smoke through different ventilation systems on smoke distribution inside the vehicle tunnel, such as water mist system with transverse ventilation with several extractions of exhaust fans Sustainable human conditions were also tested. FDS 2019 ver. was used to predict temperature, visibility, and concentration of co.
 Motivation/Background: Present work to investigate the effect of extracting the smoke by different system of ventilation on smoke spread inside the vehicular tunnel. 
 Method: By FDS 2019 that used governing equations and naver-stocks equations. 
 Results: We predicted in this paper smoke spread, temperature distribution, co concentration distribution and visibility. 
 Conclusions: This study looks at the importance of smoke control generally as well as the smoke control criteria in the automotive tunnel configuration which acknowledged them. 
 Because the smoke barrier water mist screen with a transverse ventilation device improves the smoke removal technique. FDS is a valuable method for simulating smoke diffusion as well as other effects.

AIR CLEANING TECHNOLOGIES FOR TUNNELS - HONESTY IS THE BEST POLICY FOR PROTECTING HUMAN HEALTH

Motor Vehicle tunnels capture both direct emission and re-mobilized particles as well as gasses. These captured particles and gasses must be responsibly managed to ensure risks to human health are mitigated. Active air cleaning technologies which can remove particles and gasses are sometimes used in road tunnels. Passive air dispersal techniques are commonly used. In some rare instances Passive and Active systems are used together. Unfortunately, active air cleaning technologies are often NOT used once a project is approved and operating. In the absence of a passive ventilation strategy – not using the active ventilation system may result in a greater risk of harm to people than if no active air cleaning system was used at all. The best policy for managing the risks to human health from vehicle emissions is to ensure exposure is managed – by whatever method is best in the unique circumstances of each tunnel.

Assessing the Tenability Conditions for a Heavy Goods Vehicle Tunnel Fire under the Effects of Vehicular Blockage and Point Extraction Ventilation System

Assessing the Tenability Conditions for a Heavy Goods Vehicle Tunnel Fire under the Effects of Vehicular Blockage and Point Extraction Ventilation System

Study of smoke movement characteristics in tunnel fires in high‐altitude areas

SummaryUnderstanding smoke temperature distributions and transport characteristics is of great importance to control and exhaust thermal‐driven smoke. However, previous studies have focused on this problem in plain areas, whereas ambient pressure decreases as elevation increases. This study investigates the influence of ambient pressure on the hot gas temperature distribution and movement characteristics in a tunnel fire. A series of numerical simulations are carried out in a vehicle tunnel with various heat release rates (HRRs) and ambient pressures. The results show that the maximum temperature and longitudinal temperature distribution under the tunnel ceiling increase with decreasing ambient pressure due to less heat loss caused by lower air density. In addition, the vertical temperatures of the smoke are slightly higher under lower ambient pressure, and this phenomenon makes the smoke spread slightly faster while the smoke layer thickness remains nearly the same under different ambient pressures. The results can provide a reference for tunnel lining design and ventilation arrangements in high‐altitude areas.

Simulation and Assessment of Fire Evacuation Modes for Long Underwater Vehicle Tunnels

The objective of this study is to propose a new method to evaluate the performance of different evacuation modes, and to find a rational evacuation mode for long underwater vehicle tunnels. In this study, a combined evacuation model (TPES) incorporating both a traffic flow module and a crowd evacuation module is proposed to simulate the integrated crowd evacuation with the effects of traffic flow, and the model is partially validated by a field evacuation test and a verified model Simulex. A vehicle tunnel was modeled to simulate fire-related traffic congestion and passenger evacuation, and then the evacuation performance index Im of three evacuation modes in different fire situations were calculated. The results revealed that the hybrid evacuation mode performs best among the three modes, with Im superior to other two modes by up to 26%. The transversal evacuation passage mode performs better than the longitudinal mode under the same conditions. However, the transversal and longitudinal modes can be equivalent when the passage spacing difference is within a range of 150–200 m. The critical spacing of the evacuation passage in a simple evacuation process lies in between 100 m and 350 m at confidence level of 90% for the transversal evacuation mode.

차량 배출가스 규제기준이 소요환기량에 미치는 연구

차량 배출가스 규제기준이 소요환기량에 미치는 연구

Investigation of the channelling effect on pollutants dispersion between adjacent roadway tunnels

The health risks presented by noxious vehicle emissions inside tunnels has been amplified due to the increasing use of roadway tunnels. Particularly, for adjacent roadway tunnels, vehicular emissions from the upstream tunnel can further deteriorate the air quality within the following tunnels. A scale vehicle tunnel model was designed to experimentally modelled the airflow and pollutants dispersion in contiguous roadway tunnels. The channelling effect on pollutants dispersion between adjacent roadway tunnels was studied, and factors such as ventilation speed, open road section length, traffic condition (e.g. car free, car running and traffic congestion) were considered. Pollutants mass flow rate ratio between downstream and upstream tunnels was calculated to evaluate the variation of the entrained pollutants amount. For the car free condition, pollutant can be easily entrained into the downwind tunnel when the gap distance between roadway tunnels decreased. For the car running condition with fixed tunnel gap distance, the traffic speed variation barely changed the pollutants mass flow rate ratio. Furthermore, evident influences on pollutants concentration were observed from continuous congestion and partial congestion. Lastly, numerical simulation using computational fluid dynamics approach was conducted for the car free scenario, and reasonably good agreements were found for pollutants concentration ratio compared with the experimental data. The results yielded from this study further quantified the relationships among different influential factors on the pollutants dispersion between roadway tunnels, and can contribute to an improved tunnel ventilation system design, especially for the downstream tunnel.

Designing Method of Anti-Neutralization for Vehicle Tunnel Lining Concrete

The neutral erosion of lining concrete in vehicle tunnel under the condition of load and composite acid gases is noticeable. The anti-neutral analysis and prediction of an under-river tunnel lining concrete were discussed, and the neutral level was analyzed by a numerical way based on the effect of load level and composite acid gases. It was proposed that the anti-neutral level affected by moisture content exists a high and low range and the neutral depth increase with the increase of capillary porosity. Then the design method for highly anti-neutral lining concrete of vehicle tunnel was put forward based on the corrected carbonation depth. Finally the micro-structural parameters of highly anti-neutral lining concrete, such as moisture content, content of Ca(OH)2 and capillary porosity in concrete, were analyzed. The content of Ca(OH)2 was determined to be greater than or equal to the solubility of Ca(OH)2 under the condition of environmental temperature. The critical maximum connected capillary porosity was 9.15%. The research provides basis for the design and preparation of anti-neutral lining concrete of vehicle tunnel.

A study of wind effects on smoke extraction strategies in vehicle tunnels

The effects of winds on smoke spread in a vehicle tunnel have been studied. A 2.6km vehicle tunnel in Taiwan was taken to be the case study with 50MW ultra-fast fire scenarios. It has been found that wind can have adverse effects on smoke control. The results show that winds from the tunnel ends would cause high temperature smoke spreading through the tunnel. This study explored the strategies of using tunnel ventilation jet fans and point smoke extraction in combination to counter the wind effects. It has been found that proper control strategies could restrain smoke spread in the tunnel for a period of time. Different control strategies are presented separately for fire occurs at the tunnel center and at the tunnel entrance. The results were evaluated in terms of temperature, visibility and CO concentration, specifically at 2m height from the floor level. The results show that smoke can be contained to a span of about 100m for more than 300s, and for as long as 900s in more favorable cases. The results show that tenable conditions can be maintained a period of time to prolong the evacuation time.

Assessing the influence of fuel geometrical shape on fire dynamics simulator (FDS) predictions for a large-scale heavy goods vehicle tunnel fire experiment

This paper uses four different simple geometrical shapes to simulate a large-scale heavy goods vehicle (HGV) tunnel fire experiment using Fire Dynamics Simulator, version 6 (FDS6) in order to investigate the influence of using different fuel package shapes. Simulations also investigate the influence on temperature profiles when a large target is placed downstream of the fuel package. Predictions of flame extension, temperature profiles and gas species concentrations are compared with the experimental data. The use of the geometrical shapes causes significant differences in flame extension lengths during the fully developed fire phase. The variation in temperature predictions caused by using the different fuel shapes are insignificant when a large target is present behind the fire, however this is not the case if the target is omitted especially during the fully developed phase.

Investigation of aerodynamic drag on tractor-trailer in underground road traffic

Computational fluid dynamics (CFD) simulations in 3D are performed to analyse the aerodynamic drag performance of a truck for two different on-highway road tunnel dimensions. The objective of this work is to investigate the aerodynamic drag performance of single- and multiple vehicle platooning configurations in single- and multi-lane one-way road traffic condition. Significant aerodynamic drag benefit is observed in no-traffic vehicle with an increase in gap between vehicle and road tunnel. In the vehicle platooning, the predicted aerodynamic drag benefit is up to 23% at lower vehicle separation. The aerodynamic drag benefit gradually drops in one-lane traffic and negative performance is observed from 60ft separation distance onwards. In two-lane traffic, where one vehicle is behind the other without a lateral separation, the predicted aerodynamic drag benefit is up to 60 and 44% at vehicle separation distance of 30 and 150ft, respectively. The aerodynamic drag changes are negligible with an increase in vehicle separation distance where two vehicles are separated laterally with 1.2 m distance. In all configurations, the leading vehicle aerodynamic drag changes are negligible irrespective of the vehicle separation distance.

Assessment of Bilateral Thoracic Loading on the Near-Side Occupant Due to Occupant-to-Occupant Interaction in Vehicle Crash Tests

Objective: This study aims, by means of the WorldSID 50th percentile male, to evaluate thoracic loading and injury risk to the near-side occupant due to occupant-to-occupant interaction in combination with loading from an intruding structure.Method: Nine vehicle crash tests were performed with a 50th percentile WorldSID male dummy in the near-side (adjacent to the intruding structure) seat and a THOR or ES2 dummy in the far-side (opposite the intruding structure) seat. The near-side seated WorldSID was equipped with 6 + 6 IR-Traccs (LH and RH) in the thorax/abdomen enabling measurement of bilateral deflection. To differentiate deflection caused by the intrusion, and the deflection caused by the neighboring occupant, time history curves were analyzed. The crash tests were performed with different modern vehicles, equipped with thorax side airbags and inflatable curtains, ranging from a compact car to a large sedan, and in different loading conditions such as car-to-car, barrier, and pole tests. Lateral delta V based on vehicle tunnel acceleration and maximum residual intrusion at occupant position were used as a measurement of crash severity to compare injury measurements.Result: In the 9 vehicle crash tests, thoracic loading, induced by the intruding structure as well as from the far-side occupant, varied due to the size and structural performance of the car as well as the severity of the crash. Peak deflection on the thoracic outboard side occurred during the first 50 ms of the event. Between 70 to 150 ms loading induced by the neighboring occupant occurred and resulted in an inboard-side peak deflection and viscous criterion. In the tests where the target vehicle lateral delta V was below 30 km/h and intrusion less than 200 mm, deflections were low on both the outboard (20–40 mm) and inboard side (10–15 mm). At higher crash severities, delta V 35 km/h and above as well as intrusions larger than 350 mm, the inboard deflections (caused by interaction to the far-side occupant) were of the same magnitude or even higher (30–70 mm) than the outboard deflections (30–50 mm).Conclusion: A WorldSID 50th percentile male equipped with bilateral IR-Traccs can detect loading to the thorax from a neighboring occupant making injury risk assessment feasible for this type of loading. At crash severities resulting in a delta V above 35 km/h and intrusions larger than 350 mm, both the inboard deflection and VC resulted in high risks of Abbreviated Injury Scale (AIS) 3+ injury, especially for a senior occupant.

Experimental and numerical analysis of the cooling performance of water spraying systems during a fire.

The water spray systems are effective protection systems in the confined or unconfined spaces to avoid the damage to building structures since the high temperature when fires occur. NFPA 15 and 502 have suggested respectively that the factories or vehicle tunnels install water spray systems to protect the machinery and structures. This study discussed the cooling effect of water spray systems in experimental and numerical analyses. The actual combustion of woods were compared with the numerical simulations. The results showed that although the flame continued, the cooling effects by water spraying process within 120 seconds were obvious. The results also indicated that the simulation results of the fifth version Fire Dynamics Simulator (FDS) overestimated the space temperature before water spraying in the case of the same water spray system.

Full-scale testing and modeling of the mechanical behavior of shield TBM tunnel joints

For shield TBM (Tunnel Boring Machine) tunnel lining, the segment joint is the most critical component for determining the mechanical response of the complete lining ring. To investigate the mechanical behavior of the segment joint in a water conveyance tunnel, which is different from the vehicle tunnel because of the external loads and the high internal water pressure during the tunnel's service life, full-scale joint tests were conducted. The main advantage of the joint tests over previous ones was the definiteness of the loads applied to the joints using a unique testing facility and the acquisition of the mechanical behavior of actual joints. Furthermore, based on the test results and the theoretical analysis, a mechanical model of segment joints has been proposed, which consists of all important influencing factors, including the elastic-plastic behavior of concrete, the pre-tightening force of the bolts and the deformations of all joint components, i.e., concrete blocks, bolts and cast iron panels. Finally, the proposed mechanical model of segment joints has been verified by the aforementioned full-scale joint tests.

Effects and mechanism of atmospheric multi-acidic gases on cement-based concrete linings of vehicle tunnels

In order to analyze the effects of atmospheric multi-acidic gases inside vehicle tunnels on concrete, mass gains and neutralizing depths of concrete specimens in accelerated simulation chambers filled with multi-acidic gases or single acidic gas were measured and analyzed. The results showed that the neutralizing rate of specimen in multi-gases chambers was higher by 9.6–12% than that of in corresponding single carbonation chamber. Then concrete specimen exposed to single SO2 attack exhibited high mass gain and low neutralized depth compared with those exposed to single NO2 or CO2 attack. This should be attributed to the facts that gaseous SO2 diffused into concrete nearly all dissolved in pore solution of concrete while larger ratio of gaseous CO2 or NO2 still exit and diffused in un-saturated pores of concrete. Furthermore the products CaSO4·xH2O by sulphation in concrete made the further diffusion of SO2 more difficult. Thus the concrete sulphation by SO2 mainly was concentrated on the surface of concrete while the neutralizing process of CO2 or NO2 could promote further inside the concrete.

Promoting, developing and procuring the New Tyne Crossing

This paper introduces and describes the promotion, development and procurement of the New Tyne Crossing; the construction of a new vehicle tunnel followed by refurbishment of the existing Tyne Tunnel. A suite of papers is planned to cover the construction phase and specific issues of interest. The strategy was to award a concession for the financing, design, construction and operation of the new tunnel, refurbishment and operation of the existing tunnel and operation of the Tyne pedestrian and cyclist tunnels, for a period of 30 years. The intention of the Tyne and Wear Passenger Transport Authority was to transfer the traffic risk and significant design and construction risk to the concessionaire as part of a public–private partnership (PPP) contract. This was subsequently achieved with the award of the contract to TT2/Bouygues TP in November 2007. The project boasts a number of UK firsts: a PPP for which funding has been secured totally from the revenue generated from the tolls and the first UK vehicle tunnel to have an active fire suppression system.