Automatic Road Tunnel Crack Inspection Based on Crack Area Sensing and Multiscale Semantic Segmentation

The detection of crack defects on the walls of road tunnels is a crucial step in the process of ensuring travel safetyand performing routine tunnel maintenance. The automatic and accurate detection of cracks on the surface of roadtunnels is the key to improving the maintenance efficiency of road tunnels. Machine vision technology combinedwith a deep neural network model is an effective means to realize the localization and identification of crackdefects on the surface of road tunnels.We propose a complete set of automatic inspection methods for identifyingcracks on the walls of road tunnels as a solution to the problem of difficulty in identifying cracks during manualmaintenance. First, a set of equipment applied to the real-time acquisition of high-definition images of walls inroad tunnels is designed. Images of walls in road tunnels are acquired based on the designed equipment, whereimages containing crack defects are manually identified and selected. Subsequently, the training and validationsets used to construct the crack inspection model are obtained based on the acquired images, whereas the regionscontaining cracks and the pixels of the cracks are finely labeled. After that, a crack area sensing module is designedbased on the proposed you only look once version 7 model combined with coordinate attention mechanism (CAYOLOV7) network to locate the crack regions in the road tunnel surface images. Only subimages containingcracks are acquired and sent to the multiscale semantic segmentation module for extraction of the pixels to whichthe cracks belong based on the DeepLab V3+ network. The precision and recall of the crack region localizationon the surface of a road tunnel based on our proposed method are 82.4% and 93.8%, respectively. Moreover, themean intersection over union (MIoU) and pixel accuracy (PA) values for achieving pixel-level detection accuracyare 76.84% and 78.29%, respectively. The experimental results on the dataset show that our proposed two-stagedetection method outperforms other state-of-the-art models in crack region localization and detection. Based onour proposedmethod, the images captured on the surface of a road tunnel can complete crack detection at a speed often frames/second, and the detection accuracy can reach 0.25 mm, which meets the requirements for maintenanceof an actual project. The designed CA-YOLO V7 network enables precise localization of the area to which a crackbelongs in images acquired under different environmental and lighting conditions in road tunnels. The improvedDeepLab V3+ network based on lightweighting is able to extract crack morphology in a given region more quicklywhile maintaining segmentation accuracy. The established model combines defect localization and segmentationmodels for the first time, realizing pixel-level defect localization and extraction on the surface of road tunnelsin complex environments, and is capable of determining the actual size of cracks based on the physical coordinatesystemafter camera calibration. The trainedmodelhas highaccuracy andcanbe extendedandapplied to embeddedcomputing devices for the assessment and repair of damaged areas in different types of road tunnels.

Application Strategies of Shotcrete Anchor Support Technology in Highway Bridge and Tunnel Engineering

This article analyzes the application strategies of shotcrete anchor support technology using a highway bridge-tunnel construction project as an example.The article covers various strategies,including support plan formulation,mortar shotcrete anchor construction,grid steel frame construction,steel mesh construction,and concrete support construction.This analysis aims to provide a guideline for those interested in applying this technology and improving the quality and safety of highway bridges and tunnels construction.

Discussion on Structural Health Monitoring of Urban Underground Road Tunnel

The number of urban underground road tunnels in China is increasing year by year,and health monitoring of tunnels is an effective management method to ensure their structural integrity.However,for shorter underground road tunnel projects,insufficient investment often leads to less frequent application of health monitoring systems.The application of intelligent structural health monitoring means can not only reduce the project cost but also help workers fully understand the actual situation of the tunnel structure.Therefore,this paper analyzes the characteristics,problems,and design of the urban underground road tunnel structural health monitoring system,and discusses the implementation of the urban underground road tunnel structural health monitoring system.

Research progress and development trends of highway tunnels in China

The highway tunnel system in China has in recent years surpassed Europe, the United States, and other developed countries in terms of mileage, scale, complexity, and technical achievement. Much scientific research has been conducted, and the results have greatly facilitated the rapid development of China＇s highway tunnel building capacity. This article presents the historical development of highway tunneling in China, according to specific charac- teristics based on construction and operation. It provides a systematic analysis of the major achievements and chal- lenges with respect to construction techniques, operation, monitoring, repair, and maintenance. Together with future trends of highway tunneling in China, suggestions have been made for further research, and development prospects have been identified with the for a Chinese-style highway aim of laying the foundation tunnel construction method and technical architecture.

Kinematical analysis of highway tunnel collapse using nonlinear failure criterion

For different kinds of rocks,the collapse range of tunnel was studied in the previously published literature.However,some tunnels were buried in soils,and test data showed that the strength envelopes of the soils followed power-law failure criterion.In this work,deep buried highway tunnel with large section was taken as objective,and the basic expressions of collapse shape and region were deduced for the highway tunnels in soils,based on kinematical approach and power-law failure criterion.In order to see the effectiveness of the proposed expressions,the solutions presented in this work agree well with previous results if the nonlinear failure criterion is reduced to a linear Mohr-Coulomb failure criterion.The present results are compared with practical projects and tunnel design code.The numerical results show that the height and width of tunnel collapse are greatly affected by the nonlinear criterion for the tunnel in soil.

Determination of critical parameters in the analysis of road tunnel fires

The analysis of the fluid characteristics downstream of a fire source in transportation tunnels is one the most important factor in the emergency response, evacuation, and the rescue service studies. Some crucial parameters can affect the fluid characteristics downstream of the fire. This research develops a statistical analysis on the computational fluid dynamics(CFD) data of the road tunnel fire simulations in order to quantify the significance of tunnel dimensions, inlet air velocity, heat release rate, and the physical fire size(fire perimeter) on the fluid characteristics downstream of the fire source. The selected characteristics of the fluid(response variables) were the average temperature, the average density, the average viscosity, and the average velocity. The prediction of the designed statistical models was assessed; then the significant parameters' effects and the parameters interactive effects on different response variables were determined individually. Next, the effect of computational domain length on the selection of the significant parameters downstream of the fire source was analyzed. In this statistical analysis, the linear models were found to provide the statistically good prediction. The effect of the fire perimeter and the parameters interactive effects on the selected response variables downstream of the fire, were found to be insignificant.

Landslide characteristics and its impact on tourism for two roadside towns along the Kathmandu Kyirong Highway

Frequent landslide events affect the Kathmandu Kyirong Highway(KKH),one of the most strategic Sino-Nepal highways,with multiple social effects.Amongst them,the impacts on local tourism,although being substantial,have not been studied so far.The aim of this research is to analyze the characteristics of such landslides and their influence on road damages and/or blockages as well as on local tourism industry.We analyzed the co-seismic landslides triggered by the Gorkha Earthquake,2015(7.8 Mw),the post-seismic landslides that occurred during the monsoons following the earthquake,as well as landslides which occurred or reactivated in 2018,with relation to the damage that they caused to the highway.High resolution satellite images from 2015 to 2018,and field data were used for the analysis.The Langtang avalanche that locates off the highway was also mapped due to its high impacts on tourism.Between 2015 and 2018,the number of road damaging landslides in the Betrawati-Rasuwagadhi section of KKH(where Dhunche and Syafrubesi towns are located)was 101 in the main track(MT)and 103 in the new track(NT),with respective average density of 1.46/km and 3.63/km.The dominant observed landslide types were debris slides and rock falls.Landslides were mostly concentrated in the locations with the following characteristics:1)having higher elevated area,2)being located with the‘main central thrust’and other lineaments’belts,3)belonging to the Proterozoic lesser Himalayan rocks,4)having a slope gradient of 25°-45°,5)having northern,western and southern slope aspect,6)being subjected to average annual rainfall of higher than 1,000 mm,and 7)having less than 4 km distance from the past earthquake epicenters.The results further indicated that 7 rain-induced and 4 co-and post-seismic landslides have great impact on tourist flows.An impact analysis was also assessed through a door to door questionnaire survey with local hotel operators from Dhunche and Syafrubesi towns(n=29+31).The results reveal that out of six rigorously affected sectors by landslides leading to road blockage,tourism business is the most impacted livelihood sector in these towns.The reduction of visitors in different hotels ranged from 50%-100%in Dhunche and 70%-100%in Syafrubesi for the first year aftermath of the tremor.This is higher than the respective 5%-50%tourist reduction due to raininduced landslides.Using as a reference the base year 2014,the income loss of hotels in both towns was found to be 50%-100%in 2015,20%-100%in 2016,5%-75%in 2017,and similar to 35%in 2018.These results provide insights on the synergic effect of contributing factors for cut slope as well as down slope instability along mountainous motorways and their impact on income sources for local communities.

Landscape fragmentation associated with the Qingzang Highway and its influencing factors-A comparison study on road sections and buffers

Many studies have examined the effect of roads on landscape fragmentation.Yet they rarely considered local characteristics of the road and road buffer widths.Therefore,this study that took place in the Qingzang Highway(QH)examined the variations in road buffers and road sections of landscape fragmentation.The QH was divided into 32 sections with 23 buffer areas.Based on the indicators of landscape fragmentation from 1980 to 2018,we found significant spatial heterogeneity between sections and buffers.Generally,landscape fragmentation de-creased with increasing buffer distance to the QH.For different sections,the coefficients of variation between buffers were rather high and significantly different.Therefore,fixed-width buffers may overestimate or underes-timate the spatial scope and influence intensity of a road.The impacts of road sections around provincial capitals,prefecture-level cities and main counties on landscape fragmentation were relatively extensive and formed clus-ters of highly fragmented areas.Geodetector results indicated that natural and anthropogenic factors,such as altitude,climate,distance to major settlements and socioeconomic conditions,could well explain the spatiotem-poral characteristics of landscape fragmentation.Altitude,precipitation and the distance to major settlements had higher explanatory power for landscape fragmentation in permafrost regions,whereas slope and socioeconomic condition had higher explanatory power for non-permafrost regions in Xizang Autonomous Region.

Wind tunnel tests on aerodynamic characteristics of vehicles on same-storey highway and rail bridge under crosswind

In recent years,the safety and comfort of road vehicles driving on bridges under crosswinds have attracted more attention due to frequent occurrences of wind-induced disasters.This study focuses on a container truck and CRH2 high-speed train as research targets.Wind tunnel experiments are performed to investigate shielding effects of trains on aerodynamic characteristics of trucks.The results show that aerodynamic interference between trains and trucks varies with positions of trains(upstream,downstream)and trucks(upwind,downwind)and numbers of trains.To summarize,whether the train is upstream or downstream of tracks has basically no effect on aerodynamic forces,other than moments,of a truck driving on windward sides of bridges(upwind).In contrast,the presence of trains on the bridge deck has a significant impact on aerodynamic characteristics of a truck driving on leeward sides(downwind)at the same time.The best shielding effect on lateral forces of trucks occurs when the train is located downstream of tracks.Finally,the pressure measuring system shows that only lift forces on trains are affected by trucks,while other forces and moments are primarily affected by adjacent trains.

An In-Depth Analysis of the Causes of Road Accidents in Developing Countries: Case Study of Douala-Dschang Highway in Cameroon

This paper is aimed at identifying the risk factors that mainly contribute to reckless driving and other related causes of road accidents along the Douala-Dschang highway of Cameroon. The research work started with the collection of accident reports for 2018 and 2019 from security officials in charge of road safety and the police stations of the different localities included in the sample of the study. Three hundred and eighty-two (382) road accidents reports were collected and analyzed using the 2020 version logit regression model of XLSTAT. From these analyses, it appears that, of the 382 accidents recorded during this period, six factors were identified and classified as follows: causes of accidents related to speed and carelessness, location of the accident, type of vehicle at fault, day the accident occurred, time of the accident and the age of drivers involved. These results could contribute to reduce the gravity of accidents along the Douala-Dschang highway and develop other policies in the program for road safety. In addition, this study can as much as possible equally contribute to reorienting road construction trends and development techniques in our environment.

Analysis of Detection and Treatment Schemes of Highway Tunnel Lining Cracks

Highway tunnels play a very important role in people's daily life.Among them,lining is an essential part of tunnel engineering,and the quality of lining greatly affects the overall quality of the tunnel.On this basis,the causes of lining cracks and the detection methods of existing highway tunnel lining cracks are analyzed,and the treatment countermeasures for highway tunnel lining cracks are proposed.

Applications of airtight concrete grouting to road tunnels

Road tunnel excavation often traverses coal strata, which is at risk of firedamp explosion that usually results in disaster. Airtight concrete grouting is popularly used in this kind of tunnel project. Based on the essential theory of mechanics of fluids in porous media, the principle of improving concrete airtight property and its influential factors are investigated. The proportioning tests and monitoring method for airtight concrete are introduced, which is illustrated by a case study applied to the project of the Huayinshan Tunnel. It is proved by engineering practices that the achievement of this research work is beneficial to tunneling project across coal strata.

An air cleaner for road tunnels

an air cleaner employing pulse induced plasma chemical process to remove dust and carbon monoxide (CO) in road tunnels is presented, which is composed of mainly a precipitator, a reactor, a flow control system, a power supply and a measurement system. Its performances are studied in simulated air conditions. It is found that the rate of dust removal is dependent on the voltage of the pulse power, the distance between the two dust collecting plates of the electrostatic precipitator, the effective length of the precipitator and the air flow rate in the precipitator, and that of CO removal is affected by the voltage and frequency of the super pulse power, the air flow rate in the reactor and the relative humidity of air. Applying such an cleaner of a proper design to the treatment of polluted air at a flow rate of 7 m/s can achieve the rate of dust removal up to 93 % and that of CO removal up to 72.6 %, which efficiently controls the concentrations of CO and dust under allowable limits. It is implied that the proposed air cleaner is a potential solution to air control in road tunnels, and is prominent for its performances and saving the huge cost of longitudinal ventilation tunnel or vertical vent and ventilation facilities.

Monitoring in Building Road Tunnel Across Coal Measures

In some cases coal measures,goaf,big caves,and huge faults,as well as high initial stress cannot be avoided in road tunnel excavation.These geological features may make it more difficul practical tunnel construction. So it is necessary to take strong precautious measures against gas outburst,water bursting and roof fall in a tunnel across coal measures with risk of gas outburst.The techniques,such as advance drilling exploration,multiple-cycle shallow depth hole controlled blasting,reinforced supporting,which include concrete grouting and twice supporting,and monitoring measures are often applied in the construction of tunnels and satisfied results are achieved. Results in this paper can help others to get experiences in road tunnel construction with similar geological features.

Stability analysis of tunnel face reinforced with face bolts

Face bolting has been widely utilized to enhance the stability of tunnel face,particularly in soft soil tunnels.However,the influence of bolt reinforcement and its layout on tunnel face stability has not been systematically studied.Based on the theory of linear elastic mechanics,this study delved into the specific mechanisms of bolt reinforcement on the tunnel face in both horizontal and vertical dimensions.It also identified the primary failure types of bolts.Additionally,a design approach for tunnel face bolts that incorporates spatial layout was established using the limit equilibrium method to enhance the conventional wedge-prism model.The proposed model was subsequently validated through various means,and the specific influence of relevant bolt design parameters on tunnel face stability was analyzed.Furthermore,design principles for tunnel face bolts under different geological conditions were presented.The findings indicate that bolt failure can be categorized into three stages:tensile failure,pullout failure,and comprehensive failure.Increasing cohesion,internal friction angle,bolt density,and overlap length can effectively enhance tunnel face stability.Due to significant variations in stratum conditions,tailored design approaches based on specific failure stages are necessary for bolt design.

Exploration on Defect Prevention and Maintenance Methods of Highway Tunnel Structure

Highway tunnel traffic safety is an important part of traffic safety.With the aging of tunnels,increase in traffic flow,changes in the operating environment and traffic accidents,the many problems started to occur in tunnels,affecting the operational and structural safety.In this paper,we summarize and analyze the types and causes of defects found in the process of tunnel maintenance at home and abroad,and propose corresponding suggestions for the current maintenance of the main structure of highway tunnels.

Field Test of Concrete Impermeability of Side Wall of Lakeside Highway Tunnel

The impermeability of concrete of the exterior wall of the underground tunnel in water-rich stratum is a key concern of engineers.Taking the Aixihu highway tunnel in Nanchang city as an example,the impermeability of the concrete in the side wall of the highway tunnel is tested,through multiple tests,such as the embedded steel pipe,water injection,and field observation.The results show that,under the action of 2mpa of water pressure,no water flow permeates from the side wall of the concrete tunnel,indicating that the impermeable performance of concrete tunnel in this section meets the engineering requirements,and hoping that this research can be used as a reference for other similar projects.

Resilience analysis of road tunnels subject to refurbishment work

After some tragic fire events,Directive 2004/54/EC was issued to ensure a minimum safety level for tunnels belonging to the Trans-European Road Network longer than 500 m.Nowadays,most of the Italian road tunnels are still not in compliance with the minimum safety requirements,thus refurbishment works are often planned.By developing a traffic macro-simulation model,this paper aims at assessing the resilience of an existing twin-tube motorway tunnel when one of its tubes is partially or completely closed due to planned activities.Several scenarios were investigated,also considering the availability or not of an alternative itinerary in the surrounding transportation network.The average vehicles’speed was used as a functionality parameter,while the resilience metrics were the resilience loss,the recovery speed,and the resilience index.The findings showed higher resilience losses for complete closure rather than partial closure of the tube under planned refurbishment works.The implementation of digital technologies,such as variable message signs,might reduce the resilience loss of the tunnel system.This research might represent a reference for tunnel management agencies in the choice of the most appropriate traffic control strategy to improve tunnel resilience in the event of planned activities.

Limiting Nuisance for Traffic during the Refurbishment of the Heinenoord Tunnel in The Netherlands:In Search of Resilience Possibilities

The Heinenoord Tunnel in The Netherlands connects the Hoeksche Waard Island with the city of Rotterdam.The tunnel is 614 m long,consists of two unidirectional tubes(3 lanes each)and has an average daily traffic load of 92,100 vehicles.The tunnel was opened for traffic in 1969.The structure is basically still sound,but a full refurbishment of the installations and systems is required,because they are end of life.A long closure of the tunnel(or even one tube)is not possible,because alternative routes are scarce and require significant extra travel time,not suitable for the high traffic load.Thus,various scenarios were considered to assure the accessibility of the Hoeksche Waard during the works,scheduled for 2023-2024.Multi-criteria analyses were performed for each scenario,taking into account the total project cost,societal cost(due to extra travel time)and the total required time span for the works.Refurbishment through“parallel assembly”proved to be optimal.This concept means that the new installations and systems are installed next to the current ones,that will remain in service until the end phase of the refurbishment.The existing installations and systems are only dismantled after integral testing has shown that the completed new ones work properly.This approach allows most of the works to be carried out during a series of night and weekend closures of just one tube.This limits nuisance,because one driving direction is always left undisturbed,while the closure for the other driving direction takes place in low-traffic periods.This paper describes the applied method to select the optimal refurbishment approach,as well as the(partly unconventional)measures that are implemented to enhance the resilience of the tunnel system to assure as much availability for traffic as possible,also during future maintenance works.

Overall Selection Design Based on the Mega Highway Bridge Project

In the continuous development of the modern highway and bridge engineering industry,the reasonable selection of mega highway bridges and their design is crucial.Based on this,this paper takes the actual bridge project as an example,and analyses the overall selection design of such highway bridges,including the basic overview of the project,the basic selection principle of mega highway bridge project structure and its design strategy,etc.,to provide scientific reference for its selection design.