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Road networks are essential elements of a community's infrastructure and need regular inspection. Present practice requires traffic interruptions and safety risks for inspectors. The road detection system based on vehicle-mounted lasers is also quite mature, offering advantages such as high-precision defect detection, high automation, and fast detection speed. However, it does have drawbacks such as high equipment procurement and maintenance costs, limited flexibility, and insufficient coverage range. Therefore, this paper proposes a low-cost unmanned aerial vehicle (UAV)-based alternative using imagery for automatic road pavement inspection focusing on pothole detection and classification. A slicing-based method, entitled the Pavement Pothole Detection Algorithm, is applied to the imagery after it is converted into a three-dimensional point cloud. When compared with manually extracted results, the proposed UAV-structure-from-motion (SfM) method and the associated algorithm achieved 0.01 m level accuracy for pothole depth detection and maximum errors of 0.0053 m3 in volume evaluation for cases studies of both a road and a bridge deck. [ABSTRACT FROM AUTHOR]

In many tunneling and excavation projects, free-field vertical ground movements have been used to predict subsidence, and empirical limits have been employed to evaluate risk. Validity of such approaches is largely unknown given that ground movements are in fact not one-dimensional and that adjacent applied loads are known to have an impact. This paper employed analytical and large-scale experimental efforts to quantify these issues, in the case of excavation adjacent to a reinforced concrete frame with tieback anchors and a sheetpile wall in dry sand. With this flexible system, a disproportionate amount of the soil and building movements occurred prior to installation of the first tieback, even when conservative construction practices were applied. Furthermore, free-field data generated a trough as little as one-half the size of that recorded near the building frames. Empirically based relative gradient limits generally matched the extent and distribution of the damage, while the application of various structural limits did not fully identity local damage distribution but did generally reflect global response. The use of fully free-field data or a failure to include lateral soil displacements both underpredicted building displacements by as much as 50% for low-rise concrete frames without grade beams on sand. DOI: 10.1061/(ASCE)GT.1943-5606.0000128 CE Database subject headings: Damage; Excavation; Reinforced concrete; Soil settlement; Frames; Predictions.

Aerial light detection and ranging (LiDAR) offers the potential to autogenerate detailed, three-dimensional (3D) models of the built environment in urban settings. Autogeneration is needed as manual generation is not economically feasible for large areas, and such models are needed for a wide range of applications from improved noise and pollution prediction to disaster mitigation modeling and visualization. Current laser scanning hardware and the dense geometry of urban environments are two major constraints in LiDAR scanning. This paper outlines the difficulties related to effective surface data capture, with emphasis on vertical surfaces, in an urban environment for the purpose of 3D modeling. A flight planning strategy to overcome these difficulties is presented, along with a case study of a data set collected with this strategy. The main conclusions of this study are that an appropriate amount of strip overlap, together with a flight path diagonal to the underlying street grid produces a vastly enhanced level of detail on vertical surfaces, beyond what has been previously available. DOI: 10.1061/(ASCE)0887-3801(2009)23:6(330) CE Database subject headings: Aerial surveys; Remote sensing; Three-dimensional models; Geographic information systems; Urban areas; Infrastructure.

Despite tremendous advances by women in the natural and applied sciences, where in selective fields women have surpassed men in the earning of doctoral degrees for more nearly 20 years, female enrollment levels in engineering continue to be a fraction of male enrollment. Gender disparities of more than 60% persist in undergraduate engineering enrollments and have recently worsened. As American female civil engineering enrollment has been flat for over 25 years, efforts must be taken to understand this stasis. This paper focuses primarily on secondary education preparation in terms of both attitudes toward and enrollment levels in preengineering courses such as calculus, chemistry, and physics. Additional consideration is given to enrollment and achievement in advanced placement courses, as reflected in national examination rates. This paper concludes that secondary school participation and achievement in physics courses is a critical differential factor as one explanatory element of female engineering enrollment levels and provides specific recommendations as to how to increase interest, enrollment, and achievement in physics, including the segregation of entry-level engineering courses based on previous experience. DOI: 10.106 I/(ASCE) 1052-3928(2009)135:3(95) CE Database subject headings: Engineering education; Women; Mathematics; Undergraduate study; Workplace diversity.

Building reuse is a linchpin to managing solid waste. Despite the various benefits beyond contributing to sustainability that tan be realized through building reuse, including direct and indirect cost savings, truncated construction schedules, and reduced site disruptions, little formal consideration has been given to this topic, which places professional engineers at a disadvantage when considering this as a design option. As each building project has its own specific requirements, reuse is not always the most economical solution, but, in cases where reuse is in part motivated by other factors such as heritage protection, substantial economic and environmental savings can be realized in tandem. Based on nearly two decades of professional experience, a generalized assessment method for reuse is proposed to facilitate benefit maximization. Applying this 10-step method, the costs related to building replacement and sustainable reuse are compared using two case histories and a theoretical building. A clear correlation is shown with the potential for savings as a function of project size. DOI:10.1061/(ASCE)0733-9364(2008)134:3(217) CE Database subject headings: Sustainable development; Urban areas; Rehabilitation; Pile foundations; Renovation; Demolition; Reconstruction.

A three-tiered, enterprise, geographic information system architecture offers a robust, efficient, and secure platform to potentially revolutionize disaster management by enabling support of all of the phases of governmental activity that must occur before, during, and after a disaster. Presently, both publicly and privately initiated, computer-based systems designed for disaster management cannot meet the real-time data access and analysis needs at crucial stages, especially those occurring during an actual disaster. Impediments are reflective of the proprietary, stand alone, and segregated nature of current systems. This paper proposes an integrated, infrastructure management information system as a reliable and effective alternative. Issues related to sharing data, customizing applications, supporting multiple data formats, querying visually, facilitating ubiquitous computing, and upgrading are all addressed. Achieving maximum flexibility and capacity in a disaster management system relies upon recent advances in the following areas: (1) standardized data specifications; (2) middleware services; and (3) Web-enabled, distributed computing. Key resources in designing and implementing such an arrangement are prototyped in a system that was initially designed for addressing disaster management of urban explosions. The critical details of that system are presented herein. DOI: 10.1061/(ASCE)0887-3801(2007)21:2(90) CE Database subject headings: Disasters; Databases; Emergency services; Computer models; Information management; Geographic information systems; Spatial data; Damage.

Falling trees pose a great hazard to the safe and uninterrupted use of the road transportation system during storm events. The present process of manually identifying potentially hazardous trees is laborious and inefficient. This paper presents a novel methodology for automating the tree threat identification process by using airborne laser altimetry data and a geographical information system (GIS). This methodology has the potential to be used for selecting the best possible evacuation routes based on tree hazards. The proposed method harnesses the power of spatial analysis functionality provided by existing GIS software and high-quality, three-dimensional (3D) data obtained from an airborne laser scanning system. This paper highlights the benefits related to using: (1) Height calculation of tall objects; (2) identification of hazardous objects; and (3) object identification from irregular 3D light detection and ranging point data over the currently employed manual methods. DOI: 10.1061/(ASCE)0733-947X(2006) 132:4(312) CE Database subject headings: Geographic information systems; Hazards; Highway maintenance; Trees; Highway safety; Transportation management; Evacuation.

The proposed voxel change (VC) algorithm provides accurate, scalable, and quantifiable change detection for urban aerial Light Detection and Ranging (LiDAR) scans. This VC algorithm uses MapReduce, a big data programming model, to map neighboring points into cubes. The algorithm converts each data set into a group of cubes, and classifies them into categories of building, ground, or vegetation. It then compares and quantifies changes in area or volume. Spatial discontinuity is overcome by clustering. Quality metrics are demonstrated by comparing a 1 km2 data set of Dublin, Ireland, using a 2007 scan with a point density of 225 points per square meter (pts/m2) and a 2015 scan with 335 pts/m2 (totaling more than 500 million points). By using only positional LiDAR information as the data input, the quality metric exceeded 90% across the full data set with respect to lost, new, and unchanged designations for vegetation, buildings, and ground areas, and regularly exceeded 98% for buildings. The technique successfully processes nonrectilinear features and robustly provides a quantification of change for both building expansion and vegetation at a 1 m3 level using dense, modern data sets. [ABSTRACT FROM AUTHOR]

This paper describes an investigation into the use of advanced manufacturing techniques for the creation of a new class of intermeshed steel connections that rely on neither welding nor bolting. The project detailed herein lays the groundwork to transform the steel building construction industry by advancing the underlying science and engineering precepts for intermeshed connections created from precise, volumetric cutting. The proposed system enhances the integration between design, fabrication, and installation. Fully automated, precise, volumetric cutting of open steel sections poses challenges regarding the load-transfer mechanisms and failure modes for intermeshed connections. Implementation of the intermeshed connection would cause a discontinuity in the beam; therefore, the effects of such a configuration on the behavior of the steel frame are investigated in the current paper. Load resistance and design of these connections are also explored with physical tests and finite element modeling to investigate the mechanics of intermeshed connections, including stress and strain concentrations, fracture and failure modes, and connection geometry optimization. [ABSTRACT FROM AUTHOR]

Imagery-based, three-dimensional (3D) reconstruction fromunmanned aerial vehicles (UAVs) holds the potential to provide safer, more economical, and less disruptive bridge inspection. In support of those efforts, this paper proposes a process using an imagery-based point cloud. First, a bridge inspection procedure is introduced, including data acquisition, 3D reconstruction, data quality evaluation, and subsequent damage detection. Next, evaluation mechanisms are proposed including checking data coverage, analyzing point distribution, assessing outlier noise, and measuring geometric accuracy. The overall approach is illustrated in the form of a case study with a low-cost UAV. Areas of particular coverage difficulty involved slim features such as railings, in which obtaining sufficient features for image matching proved challenging. Shadowing and large tilt angles hid or weakened texturing surfaces, which also interfered with the matching process. [ABSTRACT FROM AUTHOR]

This paper proposes a big-data approach to automatically identify and extract buildings from a digital surface model created from aerial laser scanning data. The approach consists of two steps. The first step is a MapReduce process where neighboring points in a digital surface model are mapped into cubes. The second step uses a non-MapReduce algorithm first to remove trees and other obstructions and then to extract adjacent cubes. According to this approach, all adjacent cubes belong to the same object and an object is a set of adjacent cubes that belong to one or more adjacent buildings. Finally, an evaluation is presented for a section of Dublin, Ireland, to demonstrate the applicability of the approach, resulting in a 91% quality level for the extraction of 106 buildings over 1 km², including buildings that have more than 10 adjacent components of different heights and complicated roof geometries. The proposed approach is notable not only for its big-data context but for its usage of vector data. [ABSTRACT FROM AUTHOR]

A new, meshfree method employing the node-based, smoothed point interpolation method (NS-PIM) is presented as an alternative to the nonlinear finite-element approach for concrete members. The nonlinear analysis is replaced by sequentially linear analyses (SLA), and a smeared, fixed concrete cracking model was used. A notched concrete beam was employed for validation. Using a crack band width factor of 2.0 and 10-mm nodal spacing, the peak load differed by only 3.5% from experimental results. Overall results were similar to experimental ones, as well as to those published by researchers using finite-element SLA. The approach provides two major advantages over finite-element-based SLA: (1) nodal distortion insensitivity, and (2) nodal spacing insensitivity. [ABSTRACT FROM AUTHOR]

This paper promotes the further development and adoption of infinite elements for unbounded problems. This is done by demonstrating the ease of application and computational efficiency of infinite elements. Specifically, this paper introduces a comprehensive set of coordinate and field variable mapping functions for one-dimensional and two-dimensional infinite elements and the computational steps for the solution of the affiliated combined finite-infinite element models. Performance is then benchmarked against various parametric models for deflections and stresses in two examples of solid, unbounded problems: (1) a circular, uniformly-distributed load, and (2) a point load on a semiinfinite, axisymmetrical medium. The results are compared with those from the respective closed-form solution. As an example, when the vertical deflections in Example 2 are compared with the closed form solution, the 45% error level generated with fixed boundaries and 14% generated with spring-supported boundaries is reduced to only 1% with infinite elements, even with a coarse mesh. Furthermore, this increased accuracy is achieved with lower computational costs. [ABSTRACT FROM AUTHOR]

Automated conversion of point cloud data from laser scanning into formats appropriate for structural engineering holds great promise for exploiting increasingly available aerially and terrestrially based pixelized data for a wide range of surveying-related applications from environmental modeling to disaster management. This paper introduces a point-based voxelization method to automatically transform point cloud data into solid models for computational modeling. The fundamental viability of the technique is visually demonstrated for both aerial and terrestrial data. For aerial and terrestrial data, this was achieved in less than 30 s for data sets up to 650,000 points. In all cases, the solid models converged without any user intervention when processed in a commercial finite-element method program. [ABSTRACT FROM AUTHOR]

A new algorithm is introduced to directly reconstruct geometric models of building façades from terrestrial laser scanning data without using either manual intervention or a third-party, computer-aided design (CAD) package. The algorithm detects building boundaries and features and converts the point cloud data into a solid model appropriate for computational modeling. The algorithm combines a voxel-based technique with a Delaunay triangulation-based criterion. In the first phase, the algorithm detects boundary points of the façade and its features from the raw data. Subsequently, the algorithm determines whether holes are actual openings or data deficits caused by occlusions and then fills unrealistic openings. The algorithm's second phase creates a solid model using voxels in an octree representation. The algorithm was applied to the façades of three masonry buildings, successfully detected all openings, and correctly reconstructed the façade boundaries. Geometric validation of the models against measured drawings showed overall dimensions correct to 1.2%, most opening areas to 3%, and simulation results within 5% of those predicted by CAD-based models. [ABSTRACT FROM AUTHOR]

Despite billions of dollars of annual exposure from claims and litigation related to construction-induced damage, there are no quantitatively based, agreed upon standards or procedures as to what constitutes due diligence with respect to a preconstruction, condition assessment. Similarly, the relative accuracy, reliability, and costs for various inspection approaches are not well established. This paper compares the relative performance capabilities of crack detection by sidewalk-based manual inspection with digital photography, terrestrial Light Detection and Ranging (LiDAR), and elevated manual inspections based on two brick and two concrete buildings (8.2–14.3 m high) in Dublin, Ireland. Results showed that nonmanual methods tended to overpredict crack widths by at least 5 mm and underestimate crack lengths by one-half. Digital photography, however, detected the shortest cracks (as short as 17 mm) and had no significant decline in accuracy beyond 12 m high, which has the added benefit of generating a permanent objective record. The terrestrial LiDAR proved neither particularly accurate nor cost-effective at the selected point density of less than 2 mm×2 mm. Finally, operator-based reliability problems emerged with all methods with discrepancies of at least 11%. Overall, digital photography taken and archived, but not analyzed, was the most cost-effective, accurate, and reliable approach. [ABSTRACT FROM AUTHOR]

The article discusses the need for baseline data characteristics for geographic information system-based disaster management systems. By embracing the four key characteristics of comprehensiveness, accuracy, timeliness, and accessibility for baseline data collection, an infrastructure management information systems can completely accommodate the vast range of information necessary to address the multiphase nature of disaster management and to provide capabilities to store, analyze, query, and visualize critical disaster information throughout many organizations.