Roadway Tunnel Research Articles

Abandoned coal mine tunnels: Future heating/power supply centers

We have studied three plans for re-use of the abandoned mine roadway tunnels as an energy center. These are the thermostat plan, the thermal accumulator plan, and the CAES plan. Calculations show that the thermostat plan can provide over 15,000 m 2 of building air-conditioning/heating load for each kilometer of roadway, but electric power is needed to run the system. Numerical research proved that the accumulation of hot water in the roadway for seasonal heating purposes (a temperature swing from 90 to 54 °C) is a viable possibility. The CAES plan proposes using the discarded coal mine tunnel as a peaking power station with an energy storage density over 7000 kJ/m 3. It can be concluded that presently abandoned coal mines could be reformed into future energy centers for a city.

OC/EC ratio observations in Europe: Re-thinking the approach for apportionment between primary and secondary organic carbon

Abstract This study explores a large set of OC and EC measurements in PM 10 and PM 2.5 aerosol samples, undertaken with a long term constant analytical methodology, to evaluate the capability of the OC/EC minimum ratio to represent the ratio between the OC and EC aerosol components resulting from fossil fuel combustion (OC ff /EC ff ). The data set covers a wide geographical area in Europe, but with a particular focus upon Portugal, Spain and the United Kingdom, and includes a great variety of sites: urban (background, kerbside and tunnel), industrial, rural and remote. The highest minimum ratios were found in samples from remote and rural sites. Urban background sites have shown spatially and temporally consistent minimum ratios, of around 1.0 for PM 10 and 0.7 for PM 2.5 .The consistency of results has suggested that the method could be used as a tool to derive the ratio between OC and EC from fossil fuel combustion and consequently to differentiate OC from primary and secondary sources. To explore this capability, OC and EC measurements were performed in a busy roadway tunnel in central Lisbon. The OC/EC ratio, which reflected the composition of vehicle combustion emissions, was in the range of 0.3–0.4. Ratios of OC/EC in roadside increment air (roadside minus urban background) in Birmingham, UK also lie within the range 0.3–0.4. Additional measurements were performed under heavy traffic conditions at two double kerbside sites located in the centre of Lisbon and Madrid. The OC/EC minimum ratios observed at both sites were found to be between those of the tunnel and those of urban background air, suggesting that minimum values commonly obtained for this parameter in open urban atmospheres over-predict the direct emissions of OC ff from road transport. Possible reasons for this discrepancy are explored.

Size distribution of polycyclic aromatic hydrocarbons in a roadway tunnel in Lisbon, Portugal

Atmospheric aerosols of four aerodynamic size ranges were collected using high volume cascade impactors in an extremely busy roadway tunnel in Lisbon (Portugal). Dust deposited on the tunnel walls and guardrails was also collected. Average particle mass concentrations in the tunnel atmosphere were more than 30 times higher than in the outside urban background air, revealing its origins almost exclusively from fresh vehicle emissions. Most of the aerosol mass was concentrated in submicrometer fractions (65%), and polycyclic aromatic hydrocarbons (PAH) were even more concentrated in the finer particles with an average of 84% of total PAH present in sizes smaller than 0.49 μm. The most abundant PAH were methylated phenanthrenes, fluoranthene and pyrene. About 46% of the total PAH mass was attributed to lower molecular weight compounds (two and three rings), suggesting a strong influence of diesel vehicle emissions on the production of local particulate PAH. The application of diagnostic ratios confirmed the relevance of this source of PAH in the tunnel ambient air. Deposited dust presented PAH profiles similar to the coarser aerosol size range, in agreement with the predominant origin of coarser aerosol particles from soil dust resuspension and vehicle wear products.

Physical modeling of an underground roadway excavation in geologically 45° inclined rock using infrared thermography

Physical modeling of excavation of a roadway tunnel in the geologically 45° inclined rock strata by using a newly developed physical modeling approach, the so-called “Physically Finite Elemental Slab Assemblage (PFESA)”, together with infrared (IR) thermography, were conducted for visualization and observation of the progressive development of the excavation damaged zone (EDZ). The excavation was schemed as two phases, i.e. phase 1: the full-face excavation and phase 2: the staged excavation. The experiment was performed under unbalanced confinement found in underground coal mining. The relative temperatures of the excavation zone were mapped by the IR camera, in real time and over the entire field, into thermography series which were processed using such procedures as statistics, noise removal and spectral-frequency analysis for image feature extraction. IRT, defined as the statistical mean of the thermography matrix, was used as a measure of rock responses, characterizing the full-face excavation and the staged excavation as a multi-linearity and nonlinearity processes respectively by its time-marching scheme. The temporal and spatial evolutions of the EDZ were described in detail by the denoised thermographies. Directional propagations of the excavation induced stress wave were characterized by the spectral-frequency analysis of the resultant thermographies.

Structured Distribution of Electric Power Systems: The Example of a Roadway Tunnel Architecture

Modeling of the electric system “architecture” aims to achieve performances of safety, maintenance, operation, and reliability. This paper discusses the criteria in designing special cases, such as roadway tunnels, that need a structured architecture complying with electrical loads extensively distributed and with installation requirements proper to external stresses hazards such as fire hazard. Recommendations of mechanical and electrical criteria have to be graduated according to duty categories (as environment parameters for the road tunnels). Their consideration is essential for the settlement of the design criteria, which have to concern variable configurations to simplify installation problems, to allow a flexible operation, and to optimize the cost-benefit efficiency. A special power distribution, “brush-distribution,” is suitable for the strategic buildings with higher risk for seismic event and for the road tunnels against fire. The electrical power system of a roadway tunnel could raise high values with a relevant contribution by the mechanical ventilation and the support lighting. The authors suggest an adaptive criterion in designing the support lighting system in order to mitigate the cost and the energetic impact.

Optimization of Emergency Ventilation Strategies in a Roadway Tunnel

In order to evaluate the effectiveness of in-place emergency ventilation strategies to control smoke spread in the event of a fire in a section of a roadway tunnel, both numerical and experimental studies were performed. The experimental study was conducted to provide the necessary initial and boundary conditions for the numerical phase of the investigation. A fire heat release rate of 1 MW was used in all fire tests. This fire heat release rate was selected to minimize the risk of damage to the tunnel and its associated systems while producing reliable data for visualizing the smoke movement in the tunnel. The numerical study used Computational Fluid Dynamics, Fire Dynamic Simulator version 4.0 to investigate smoke removal in the tunnel for large fire of 30 MW (bus or truck on fire). In total, four field fire tests and seven numerical simulations were conducted. Based on the study results, recommendations were made to optimize the ventilation scenarios in the tunnel section. This article presents the details of the study as well as the recommendations made.

Modal Characteristics of Elemental and Organic Carbon in an Urban Location in Guangzhou, China

Carbonaceous matter is a major constituent in urban aerosols, especially in those collected in China. The size distributions of elemental carbon (EC) and organic carbon (OC) in the range of 0.01–18 μm were measured in an urban location in Guangzhou, China in July 2006. The EC size distribution in the accumulation-mode size was characterized by three significant modes with mass median aerodynamic diameters (MMAD) of ∼0.15 μm, ∼0.40 μm, and ∼0.90 μm, with the second one being the most prominent and accounting for approximately half of the total EC mass. The coexistence of the first two accumulation modes in Guangzhou's urban atmosphere could be explained to be a result of emissions from vehicles operating at different loadings. The dominance of the EC accumulation mode at ∼0.40 μm has not often been reported in studies conducted in developed countries, but this observation is consistent with EC size distributions measured in a roadway tunnel in this region. This information is important when modeling the role of EC in modulating the radiative balance and investigating the health effects of EC. The third accumulation mode was postulated to be a result of in-cloud processing after emission. OC had the same size modes as EC but different mass distributions among the modes. The carbonaceous materials in the nucleation mode were dominated by OC. Among particles in the accumulation size range, the OC/EC ratio was higher in the third accumulation mode (MMAD: 0.90 μm) than in the first two accumulation modes, suggesting that in-cloud processing was an important pathway for accumulating OC mass during atmospheric processing of EC particles.

Optical and physical properties of primary on-road vehicle particle emissions and their implications for climate change

During the summers of 2004 and 2006, extinction and scattering coefficients of particle emissions inside a San Francisco Bay Area roadway tunnel were measured using a combined cavity ring-down and nephelometer instrument. Particle size distributions and humidification were also measured, as well as several gas phase species. Vehicles in the tunnel traveled up a 4% grade at a speed of approximately 60 km h −1. The traffic situation in the tunnel allows the apportionment of emission factors between light duty gasoline vehicles and diesel trucks. Cross-section emission factors for optical properties were determined for the apportioned vehicles to be consistent with gas phase and particulate matter emission factors. The absorption emission factor (the absorption cross-section per mass of fuel burned) for diesel trucks (4.4±0.79 m 2 kg −1) was 22 times larger than for light-duty gasoline vehicles (0.20±0.05 m 2 kg −1). The single scattering albedo of particles—which represents the fraction of incident light that is scattered as opposed to absorbed—was 0.2 for diesel trucks and 0.3 for light duty gasoline vehicles. These facts indicate that particulate matter from motor vehicles exerts a positive (i.e., warming) radiative climate forcing. Average particulate mass absorption efficiencies for diesel trucks and light duty gasoline vehicles were 3.14 ± 0.88 m 2 g PM - 1 and 2.9 ± 1.07 m 2 g PM - 1 , respectively. Particle size distributions and optical properties were insensitive to increases in relative humidity to values in excess of 90%, reinforcing previous findings that freshly emitted motor vehicle particulate matter is hydrophobic.

Ground Vibration Caused by Tunnel Construction and its Effect on an Electron Microscope

In this study, we observed the vibrations caused by the construction of a roadway tunnel excavated using the New Austrian Tunneling Method (NATM) in an urban area. We analyzed the resulting vibrations and disturbances and their effect on a high-voltage electron microscope (HVEM). The characteristics of the construction equipment, various construction tasks, wave propagation and attenuation in the soil, along with the transmission of vibration forces to adjacent buildings were also clarified. These findings were combined and the effects on the HVEM were examined to model vibration-induced disturbances. The accuracy of these findings was confirmed by comparing the results obtained with actual observations that were recorded later. The findings of this study are expected to enhance the ability to distinguish between the many factors involved in vibration-induced disturbances caused by equipment. The findings could also be applied to monitoring construction activities and predicting the effects of vibration-induced disturbances on high-precision equipment.

Emission factors of PM species based on freeway measurements and comparison with tunnel and dynamometer studies

Emission factors of various particle species from light- and heavy-duty vehicles (LDVs and HDVs, respectively), including organic and elemental carbon (OC and EC), sulfate, polycyclic aromatic hydrocarbons (PAHs), hopanes, steranes, trace metals, elements, and particle number (PN), were estimated based on roadway measurements. Sampling campaigns were conducted at two different roadways: the CA-110 highway (where only gasoline-powered vehicles are allowed), and the I-710 freeway (where about 20% of the total number of vehicles are diesel-powered trucks). The particulate matter (PM) emission factors determined in these roadways were compared to those reconstructed from recent source emission data from the Caldecott tunnel [Phuleria, H.C., Geller, M.D., Fine, P.M., Sioutas, C., 2006. Size-resolved emissions of organic tracers from light- and heavy-duty vehicles measured in a California roadway tunnel. Environmental Science and Technology 40 (13), 4109–4118], and those from previous tunnel and chassis dynamometer studies. Very good agreement between estimated and reconstructed emission factors was found for PN, EC, sulfate, high-molecular-weight (MW) PAHs, hopanes and steranes. This suggests that PM-speciated chemical data collected at roadsides can be used to calculate reliable emission factors for several important particle species at other locations characterized by a similar mix of on-road motor vehicles. The agreement between our results and other studies in the emission factors of trace elements and metals varied from very good (for species such as Cu, Mo, Ba, Pb) to poor (for species such as Mg, Fe, Ca), probably because the atmospheric concentrations of the latter elements are associated with both traffic and non-traffic sources, and the relative abundances of Mg, Ca, and Fe in road dust varies considerably across locations. The emission factors of OC and EC were clearly the highest for HDVs, and those of PAHs, hopanes, and steranes from our roadway measurements were well within the range of values reported in the literature from tunnel and dynamometer studies. The approach presented in this paper allows for a straight-forward estimation of PM emission factors from ambient, near-freeway measurements. Although the uncertainties inherent in the method proposed here must be acknowledged (e.g. assumptions were made to estimate the average fleet composition and the total carbon content in the vehicles’ exhaust), our results are generally in very good agreement with those in the available literature for most non-labile PM species.

Roadside measurements of size-segregated particulate organic compounds near gasoline and diesel-dominated freeways in Los Angeles, CA

Individual organic compounds such as hopanes and steranes (originating in lube oil) and selected polycyclic aromatic compounds (PAHs) (generated via combustion) found in particulate emissions from vehicles have proven useful in source apportionment of ambient particulate matter (PM). Detailed information on the size-segregated (ultrafine and accumulation mode) chemical characteristics of organic PM during the winter season originating from a pure gasoline traffic freeway (CA-110), and a mixed-fleet freeway with the highest fraction of heavy-duty diesel vehicles in the state of California (I-710) is reported in this study. Hopanes and steranes as well as high molecular weight PAHs such as benzo(ghi)perylene (BgP) and coronene levels are found comparable near these freeways, while elemental carbon (EC) and lighter molecular weight PAHs are found much elevated near I-710 compared to CA-110. The roadway organic speciation data presented here are compared with the emission factors (EFs) measured in the Caldecott tunnel, Berkeley, CA [Phuleria, H.C., Geller, M.D., Fine, P.M., Sioutas, C., 2006. Size-resolved emissions of organic tracers from light- and heavy-duty vehicles measured in a California roadway tunnel. Environmental Science and Technology 40, 4109–4118] for light-duty vehicles (LDVs) and heavy-duty vehicles. Very good agreement is observed between CA-110 measurements and LDV EFs as well as I-710 measurements and corresponding reconstructed EFs from Caldecott tunnel for hopanes and steranes as well as heavier PAHs such as BgP and coronene. Our results, therefore, suggest that the EFs for hopanes and steranes obtained in tunnel environments, where emissions are averaged over a large vehicle-fleet, enable reliable source apportionment of ambient PM, given the overall agreement between the roadway vs tunnel concentrations of these species.

Particle Concentration and Characteristics near a Major Freeway with Heavy-Duty Diesel Traffic

This study presents the number, surface and volume concentrations, and size distribution of particles next to the 1-710 freeway during February through April 2006. 1-710 has the highest ratio (up to 25%) of heavy-duty diesel vehicles in the Los Angeles highway network. Particle concentration measurements were accompanied by measurements of black carbon, elemental and organic carbon, and gaseous species (CO, CO2). Using the incremental increase of CO2 over the background to calculate the dilution ratio, this study makes it possible to compare particle concentrations measured next to the freeway to concentrations measured in roadway tunnels and in vehicle exhaust. In addition to the effect of the dilution ratio on the measured particle concentrations, multivariate linear regressions showed that light and heavy organic carbon concentrations are positively correlated with the particle volume in the nucleation and accumulation modes, respectively. Solar radiation was also positively correlated with the particle surface concentration and the particle volume in the accumulation (40-638 nm) mode, presumably as a result of secondary particle formation. The methods developed in this study may be used to decouple the effect of sampling position, meteorology, and fleet operation on particle concentrations in the proximity of freeways, roadway tunnels, and in street canyons.

Optimal interval of tunnel with small spacing considering visco-elastic plasticity

Based on different surrounding rock classifications, the numerical simulation of visco-elasto-plastic surrounding rock was studied for three roadway tunnels with small spacing, especially analyzing the visco-elasto-plastic effect in the process of rock mass excavation by the step. By the numerical imitation and comparing analysis, the damage characteristic and the deformation law of surrounding rock were given under the same construction method for different surrounding rock classifications of three driveway tunnels, and the deformation law of interval wall and the relationship between the surrounding rock classification and the interval were obtained under the particular construction method for tunnels with small spacing. The minimum interval was selected for engineering design reference under the same excavation way, and a set of reasonable value ranges was given. The reference data and the theoretical basis were provided for the development and construction design of roadway tunnels with small spacing.

Low Molecular Weight Dicarboxylic Acids, Ketoacids, and Dicarbonyls in the Fine Particles from a Roadway Tunnel: Possible Secondary Production from the Precursors

Low molecular weight dicarboxylic acids (DCAs), ketoacids, and alpha-dicarbonyls have been determined for the PM2.5 samples in a Hong Kong roadway tunnel, using a water extraction followed by a butyl ester and/or dibutyl acetal derivatization technique. For the most wintertime sampling runs, outlet and inlet concentrations of the quantified compounds were found to be quite similar (ca. 10% differences), leading to the conclusion that direct emissions of the organic compounds are insignificant from vehicles in hot-stabilized operations although vehicular emissions can provide important precursors to them. In contrast, a significant concentration increase of most compounds was observed at the outlet station compared to the inlet station in the summertime runs, which might be explained by the secondary production of aerosols in the tunnel. The organic compounds studied comprised a small fraction (<1%) of aerosol organic carbon (OC). In winter, their abundances relative to that of OC in outlet samples were found to be significantly less than those in inlet samples. On the basis of the summer data, apparent secondary production factors of the compounds were calculated, which indicate that adipic and m-phthalic acids can be favorably formed in the tunnel. However, like other DCAs, direct emissions of adipic, m-phthalic, and p-phthalic acids from automobiles are suggested to be insignificant.

Size Distribution Characteristics of Elemental Carbon Emitted from Chinese Vehicles: Results of a Tunnel Study and Atmospheric Implications

The size distribution characteristics of elemental carbon (EC) emissions from Chinese vehicles have not been previously described. In this study, we collected size-segregated aerosol samples using a 10-stage MOUDI sampler (0.056-18 microm) in the Zhujiang tunnel, a roadway tunnel in the urban area of Guangzhou, China. The samples were analyzed for EC, organic carbon (OC), and inorganic ions. Fine particles had an OC/EC ratio of 0.57, indicating a dominant contribution of EC from diesel vehicles. Both EC and OC showed a dominant accumulation mode with a mass median aerodynamic diameter (MMAD) of 0.42 microm. In comparison, studies available in the literature typically reported a much lower MMAD for EC (approximately 0.1 microm) in vehicular emissions in North America. A theoretical analysis indicated that the larger EC particles observed in this study could not have resulted from after-emission growth processes (i.e., water accretion, coagulation, and vapor condensation). This leaves operating conditions such as high engine loads and low combustion efficiencies, which are more prevalent in diesel-fueled Chinese vehicles, as a more plausible inherent reason for producing the larger EC agglomerates. While fresh 0.1 microm EC particles are unlikely to act as cloud condensation nuclei (CCN), calculations showed that EC particles as large as 0.42 microm are effective CCN at atmospherically relevant critical supersaturation values of less than 1%. As a result, fresh EC particles from Chinese vehicle emissions could readily undergo cloud processing and form internal mixtures with sulfate in the residue droplet mode particles. This prediction is consistent with observations that EC frequently showed a dominant droplet mode in urban atmospheres in this region. The internal mixing of EC with highly hygroscopic sulfate would facilitate its removal by wet deposition and shorten its lifetime in the atmosphere. In addition, the light-absorbing capabilities of EC particles could also be enhanced due to their internal mixing with sulfate. Numerical aerosol models need to take these factors into consideration for better predictions of the behaviors and effects of urban aerosols in China.

Size-Resolved Emissions of Organic Tracers from Light- and Heavy-Duty Vehicles Measured in a California Roadway Tunnel

Individual organic compounds found in particulate emissions from vehicles have proven useful in source apportionment of ambient particulate matter. Species of interest include the hopanes, originating in lube oil, and selected PAHs generated via combustion. Most efforts to date have focused on emissions and apportionment PM10 or PM2.5 However, examining how these compounds are segregated by particle size in both emissions and ambient samples will help efforts to apportion size-resolved PM, especially ultrafine particles which have been shown to be more potent toxicologically. To this end, high volume size-resolved (coarse, accumulation, and ultrafine) PM samples were collected inside the Caldecott tunnel in Orinda, California to determine the relative emission factors for these compounds in different size ranges. Sampling occurred in two bores, one off-limits to heavy-duty diesel vehicles, which allows determination of the different emissions profiles for diesel and gasoline vehicles. Although tunnel measurements do not measure emissions over a full engine duty cycle, they do provide an average emissions profile over thousands of vehicles that can be considered characteristic of "freeway" emissions. Results include size-fractionated emission rates for hopanes, PAHs, elemental carbon, and other potential organic markers apportioned to diesel and gasoline vehicles. The results are compared to previously conducted PM2.5 emissions testing using dynamometer facilities and othertunnel environments.

Video Incident Detection Tests in Freeway Tunnels

European regulations for the management of roadway tunnels became much more stringent after the 1999 Mount Blanc inferno. Several video image processing (VIP) devices for traffic surveillance have automated incident detection (AID) capabilities. Autoscope, Citilog, and Traficon were invited to make installations for testing their VIPs with eight preexisting cameras in Attica Tollway tunnels. The suppliers of the competing devices were responsible for setting and calibrating the devices for best results. No literature was found in which VIPs developed in 2000 or later were evaluated for incident detection. A 3,013-incident database was used to derive the detection rate and false-alarm rate for each device for the whole database, separately for each closed-circuit television camera, and by type of incident. Changes in detection performance after each manufacturer's intervention were evaluated. T-tests were conducted on the significance of effects of low, medium, and high volume in weekday and weekend traffic, and natural or artificial lighting. A separate analysis was conducted for incidents that were artificially generated by Attica Tollway engineers and staff at off-peak times. The results show promise, but the evaluated performance was poor because of three reasons: low maturity of the technology, complex algorithms due to the provision of extensive functionality, and suboptimal camera location and height for image processing, but VIP devices must adapt to tunnel limitations.

Video Incident Detection Tests in Freeway Tunnels

European regulations for the management of roadway tunnels became much more stringent after the 1999 Mount Blanc inferno. Several video image processing (VIP) devices for traffic surveillance have automated incident detection (AID) capabilities. Autoscope, Citilog, and Traficon were invited to make installations for testing their VIPs with eight preexisting cameras in Attica Tollway tunnels. The suppliers of the competing devices were responsible for setting and calibrating the devices for best results. No literature was found in which VIPs developed in 2000 or later were evaluated for incident detection. A 3,013-incident database was used to derive the detection rate and false-alarm rate for each device for the whole database, separately for each closed-circuit television camera, and by type of incident. Changes in detection performance after each manufacturer's intervention were evaluated. T-tests were conducted on the significance of effects of low, medium, and high volume in weekday and weekend traffi...

Geophysical characterisation of a rockslide in an alpine region

A combination of geophysical methods has been used for the characterisation of a rockslide area, located in the Graie Alps, NW of Italy, where the construction of a roadway tunnel has been planned. Electrical resistivity tomography (ERT), seismic refraction tomography (SRT) and spectral analysis of surface waves (SWM) have been adopted to determine the overburden thickness and the geometry of the sliding surfaces. The geomechanical characterisation of rock mass was performed by means of horizontal seismic profiles (HSP) and sonic log in a horizontal borehole. The results have been calibrated by comparing the geophysical responses with the geological evidence derived from boreholes and with the movements recorded using inclinometric probe. Moreover, borehole geophysics results were validated by the results of laboratory measurements performed on core samples. The integration of geophysical and geotechnical results allowed the definition of a subsoil model for the investigated area and provided the necessary data for the design of the roadway tunnel. The study shows that surface and borehole geophysical techniques could be an efficient and cost-effective tool in rockslide investigations.

A case study of the single and size-resolved particles in roadway tunnel in Seoul, Korea

Abstract Particle sampling was conducted at the center of Buk-Ak tunnel, which is one of heavily polluted tunnels in Seoul, in October 2000. The sampling equipments consist of a 2-stage filter pack sampler and an Andersen impactor sampler. Micro-particle induced X-ray emission (PIXE) was applied to determine the elemental composition of individual particles (>1.2 μm). The thermal/optical reflectance (TOR ® ) method was also employed in analyzing of EC and OC. Mass concentrations of fine and coarse particles are 177 and 40 μg m −3 , respectively. The most important contributor to particle mass concentration in the present study is carbonaceous components. Most of the individual particles are found to be internally mixed with soil-derived and trace elemental components.