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Abstract: Many transportation authorities in the United States and Canada require condition assessments of concrete bridge decks and roadways as part of scheduled rehabilitation and maintenance programs. Nondestructive test (NDT) methods and laboratory studies are commonly used by engineering consultants to perform these evaluations. Amongst typical NDT methods, ground-penetrating radar (GPR) is one of the best suited to accomplish this task. Unfortunately, reported test results are oftentimes ambiguous, due to the current numerical analysis approach to evaluate the data. This paper describes some of the shortcomings of numerical analysis of GPR profiles and it introduces an alternative method developed by the authors. Several examples of actual field investigations are described, where the computer-assisted visual interpretation of GPR profiles was used to validate and eventually improve this new analysis approach. The authors’ project experiences on several structures indicate that mapping defects by visual identification of corrosion-induced anomalies in concrete is a much more accurate way of mapping defects. The results obtained from the field applications suggest that use of the computer-assisted visual interpretation of GPR data is an efficient and reliable approach that can be used by experienced GPR analysts. [Copyright &y& Elsevier]

Ground penetrating radar (GPR) and lithologic data reveal six Pleistocene sea-level highstand sequences, forming two composite terraces along the northern margin of Delaware Bay in southern New Jersey, USA. The upper terrace (+18 to +9 m MSL) is underlain by four estuarine-marine sequences of middle Pleistocene age, while the lower terrace (+6 m–MSL) contains 2 middle to late Pleistocene sequences. Separating the 2 terraces is a variably sloping escarpment (Cedarville) created by erosion during at least 2 high sea-level events. Intensive radar imaging and boring of these 6 unconformity-bounded units allows for their interpretation in a sequence-stratigraphic context, identifying transgressive, highstand, and regressive phases. Higher than present sea levels of +14, +12, +6, and +16 m during the middle Pleistocene, and +5 m during the middle and/or late Pleistocene are indicated by these sedimentary sequences, suggesting relative stability of this section of the Atlantic Coastal Plain during the past 500 ka. GPR analysis of coastal drainage modification reveals a contrasting lowstand sequence of incised paleovalleys, supporting the interpretation that these bay-margin deposits contain one of the most complete sections of late Quaternary highstand stratigraphy in the Mid-Atlantic region. For appendix see http://www.elsevier.nl/locate/quascirev. [Copyright &y& Elsevier]

Data gathered by electrical resistivity tomography (ERT) and ground-penetrating radar (GPR) were used to produce a three-dimensional image of subsurface soft-sediment deformation structures developed on the modern Lake Powell delta at Hite, Utah. ERT and GPR lines were run orthogonal across the crater. ERT resolved a low-resistivity layer up to 2 m thick in the area near the vents within the crater. This low-resistivity layer thins toward the margins representing clays ejected from the vents. Below and adjacent to this layer is a high-resistivity layer that reflects delta top and pro-delta sands. The deepest zone recognized in the ERT profiles consists of a low-resistivity layer, clay deposits that accumulated during the maximum lake high stand. This clay zone is connected to the vent within the crater by a conduit that changes diameter vertically. GPR profiles recognized the presence of collapse features restricted to the proximity of the vent. The geometry of the model is consistent with those proposed for marine pockmarks that can be generated seismically or aseismically with the exception of subaerial exposure after the dome stage development. [ABSTRACT FROM AUTHOR]

In order to develop a new field method for the science of paleontology, Ground Penetrating Radar (GPR) surveys were conducted at two sauropod (Dinosauria) quarries in the Cretaceous rocks of Texas. These sites were chosen due to the presence of vertebrate fossils and the varying lithologic settings. The surveys were conducted using a Pulse EKKO transmitter and receiver antennae pair at varying frequencies. Higher survey frequencies allow for greater resolution at the cost of decreased survey penetration depth. Anomalies detected in the subsurface were plotted on quarry maps. The GPR-enhanced maps were then given to paleontological field teams to guide their excavation efforts. Fossils were accurately located and excavated using this technique. [Copyright &y& Elsevier]

Lack of accurate and complete utility records is a root cause of utility strikes that occur on average once every minute in the United States, leading to hundreds of deaths and billions of dollars in financial losses. Ground-penetrating radar (GPR) has emerged as a promising tool to detect, locate, and measure underground pipes. Many algorithms have been devised to process GPR scans to determine pipe location and burying depth. Their accuracy depends on the relative angles between the GPR survey trajectory and the buried pipes. Perpendicular-to-pipe scanning yields the highest detectability, and along-pipe scanning yields the highest planimetric and depth accuracy. However, the challenge in practice is to maintain such ideal angles while not knowing the exact orientation of the pipes. This paper devises a novel spatial reasoning mechanism to enable the automation of GPR survey trajectory planning and adjustment based on ill-shaped and incomplete GPR signatures to achieve ideal angles in real time. The spatial reasoning mechanism provides trajectory adjustment suggestions based on the connection between the GPR signatures extracted from GPR scans and the relative angles between the GPR trajectory and underground pipes. The adjustment process continues until the GPR signatures from synthetic data under ideal angles and from field survey converge, and further adjustment no longer improves the results. Both indoor and field experiments have been conducted for validation. The results show that the newly developed method is capable of guiding the adjustment process in real time to achieve ideal angles and collect high-quality GPR data, leading to a more accurate estimation of pipe locations and burying depths. It has the great potential to support the operation of robotic unmanned ground vehicles (UGV) or unmanned aircraft system (UAS) to fully automate the GPR field survey. • A spatial reasoning process that guides survey robots to adaptively adjust trajectory in field • The trajectory planning of robotic GPR-UGV is near real-time. • The correlation of GPR signatures and spatial configurations are modeled and established. • Indoor and outdoor experiments were performed to validate the new method. • The new method achieves high accuracy and efficacy in mapping underground pipes. [ABSTRACT FROM AUTHOR]

Abstract: The US Army owns and maintains approximately 2000 bridges on its installations spread out in the United States and around the world. From this inventory, 67% are concrete bridges, most of which do not have design or as-built plans to effectively evaluate their condition/capacity. In addition, military vehicles have unique characteristics that are difficult to take into account when analytical analyses are performed. For these purposes, the US Army Engineer Research and Development Center has been adapting non-destructive techniques. The most promising concept explored thus far involves bridge rating through non-destructive load testing in combination with Ground Penetrating Radar (GPR) techniques. Field load testing techniques are valuable for evaluating the capacity of existing bridges and accurately characterize the structure’s live-load response while GPR techniques provide valuable information regarding the internal reinforcement as well as the condition of the concrete. This article will provide a brief description as well as the results from recent evaluations performed on reinforced concrete bridges at military installations. [Copyright &y& Elsevier]

Abstract: The integration of geophysical data into the subsurface characterization problem has been shown in many cases to significantly improve hydrological knowledge by providing information at spatial scales and locations that is unattainable using conventional hydrological measurement techniques. In particular, crosshole ground-penetrating radar (GPR) tomography has shown much promise in hydrology because of its ability to provide highly detailed images of subsurface radar wave velocity, which is strongly linked to soil water content. Here, we develop and demonstrate a procedure for inverting together multiple crosshole GPR data sets in order to characterize the spatial distribution of radar wave velocity below the water table at the Boise Hydrogeophysical Research Site (BHRS) near Boise, Idaho, USA. Specifically, we jointly invert 31 intersecting crosshole GPR profiles to obtain a highly resolved and consistent radar velocity model along the various profile directions. The model is found to be strongly correlated with complementary neutron porosity-log data and is further corroborated by larger-scale structural information at the BHRS. This work is an important prerequisite to using crosshole GPR data together with existing hydrological measurements for improved groundwater flow and contaminant transport modeling. [Copyright &y& Elsevier]

Abstract: Observations from mapping since the 19th century and aerial imagery since 1930 have been used to study changes in the aeolian geomorphology of coastal parabolic dunes over the last ~170years in the Walking Dune Field, Napeague, NY. The five large parabolic dunes of the Walking Dune Field have all migrated across, or are presently interacting with, a variably forested area that has affected their migration, stabilization and morphology. This study has concentrated on a dune with a particularly complex history of stabilization, reactivation and migration. We have correlated that dune''s surface evolution, as revealed by aerial imagery, with its internal structures imaged using 200MHz and 500MHz Ground Penetrating Radar (GPR) surveys. Both 2D (transect) and high-resolution 3D GPR imagery image downwind dipping bedding planes which can be grouped by apparent dip angle into several discrete packages of beds that reflect distinct decadal-scale episodes of dune reactivation and growth. From aerial and high resolution GPR imagery, we document a unique mode of reactivation and migration linked to upwind dune formation and parabolic dune interactions with forest trees. This study documents how dune–dune and dune–vegetation interactions have influenced a unique mode of blowout deposition that has alternated on a decadal scale between opposite sides of a parabolic dune during reactivation and migration. The pattern of recent parabolic dune reactivation and migration in the Walking Dune Field appears to be somewhat more complex, and perhaps more sensitive to subtle environmental pressures, than an idealized growth model with uniform deposition and purely on-axis migration. This pattern, believed to be prevalent among other parabolic dunes in the Walking Dune Field, may occur also in many other places where similar observational constraints are unavailable. [Copyright &y& Elsevier]

Abstract: The Columbia River littoral cell (CRLC) consists of four subcells (totaling 160km in length) that are unique in the West Coast of the United States, in that they contain prograded barriers and beach plains, reaching 0.5–3km in width (Fig. 1). The prograded beach deposits (1–5ka in age) overlie shoreface deposits (1–8ka in age), as identified in 18 ground penetrating radar profiles, and sampled from 24 boreholes. Two competing hypotheses were initially proposed to account for the origins of these unique, progradative shorelines: (1) cross-shore feeding by onshore wave transport of pre-Holocene sand from the submerged shelf, and (2) longshore dispersal of nearshore sand that was supplied to the littoral system by bedload sediment discharge from the Columbia River during the Holocene. The CRLC sand forming the shoreface deposits is fine (diameter 0.2±0.02mm) and rich in lithic fragments (20–40% by volume). Gravel and shell lag layers are uncommon in most of the CRLC shoreface deposits, but they show greater abundance locally near ravinement surfaces, tidal inlets, and in the Clatsop subcell, located south of the Columbia River mouth. Gravel and granule layers increase upsection in barriers south of the Columbia River and downsection in barriers at the northern end of the littoral system. These trends suggest different mechanisms of shoreface sediment feeding within the four subcells. However, borehole samples from all four subcells show the same sand provenance, i.e., post-glacial Columbia River sand, which is identified by high ratios of hypersthene:augite in heavy-mineral fractions. Selected shoreface sections were dated (0.5–8ka) by AMS radiocarbon analysis of articulated-shell and wood fragments recovered from auger flights (3–22m depth subsurface). Relatively young shoreface deposition (2.5ka at −6.5m elevation NGVD88) in the Clatsop subcell south of the Columbia River shows a net-southward beach transport that fed shoreface and beachface progradation into deeper water. Older and deeper shoreface deposition (4.4ka at −7.1m elevation) in the Long Beach subcell north of the Columbia River was a result of the filling of innermost-shelf accommodation space prior to beachface progradation. The total volume of shoreface sand deposited under the barrier spits and beach plains of the CRLC is estimated to be 6–7km3 deposited since 6–8ka. There was a net-northward transport of littoral sand (∼1×106 m3 year− 1) along the nearshore and inner-shelf; subsequently some of this sand was transported onshore to feed beaches of the northernmost subcells. Columbia River sand was also the source for the formation of the offshore shelf wedge above the transgressive ravinement surface, and for the filling of major tidal basins located north of the Columbia River. In summary, the unique progradational history of the CRLC barriers and beach plains derives from the combination of (1) longshore dispersal of fine sand discharged from the Columbia River during Holocene time, and (2) across-shore feeding of beaches at the northern end of the littoral system from fine sand carried north along the nearshore and the inner-shelf. [Copyright &y& Elsevier]

Abstract: Beaches and barrier spits of the Columbia River littoral cell (CRLC), 160km in length, experienced substantial progradation, 0.5–2.5km in width, during the late Holocene. The accreted beach plains and barriers preserved evidence of episodic catastrophic retreat that was forced by coseismic subsidence. The abrupt subsidence events (0.5–1.5m submergence) are associated with slip on the underlying Cascadia megathrust, with a mean recurrence interval of ∼500yr. Ground penetrating radar (GPR) profiles taken across the barriers and beach plains show high-angle beach retreat scarps (3–15m vertical relief) and foredune-ridge slump scarps (5–15m vertical relief). The upper-shoreface retreat features are correlated throughout the littoral cell by radiocarbon age, position relative to abandoned foredune ridges, and distinct sequences of large and small scarps. Particularly large retreat scarps (10–15m in height) are associated with the first oldest and fourth oldest prehistoric scarps, ‘A’ and ‘D’, respectively. A maximum of 10 retreat scarps in the Long Beach subcell date from 216±211 calRCYBP to 4756±114 calRCYBP. The youngest seven scarps (A–G) are correlated between all four subcells, showing a regional response to the coseismic strain cycles. Backshore disturbance features (1–3m vertical relief) are observed in the GPR profiles, but they are not identified here due to their discontinuities between adjacent profiles at ∼5km longshore spacing. The seven regional scarps (A–G) are directly correlated to seven coseismic subsidence events, reported to date between 0.3 and ∼3.2ka. The correlation of scarps to earthquake events provides high-resolution proxy ages for shoreline positions in late Holocene time. The proxy shoreline positions are dated at 0.3, 1.1, 1.3, ∼1.7, ∼2.5, ∼2.8, and ∼3.2ka, based on buried wetland sequences from adjacent tidal basins. The paleoshoreline dating demonstrates that the onset of net shoreface progradation (between 4.7 and 0.3ka) was delayed with increasing distance (0–100km) from the Columbia River sand source. The history of beach progradation reflects the sequential filling of bay and shoreface accommodation spaces located down-drift of the Columbia River mouth. These late Holocene shoreline changes portend future redistributions of existing sand within the littoral system as the limited sand reserves continue to migrate away from the Columbia River mouth source. [Copyright &y& Elsevier]

Subsurface drainage pipes are commonly used in the Midwestern United States to reduce excess soil moisture and improve crop yields. However, they are the considerable source of nonpoint pollution due to nutrient losses. Detecting the locations of drainage pipes is crucial for water quality management, but information about drainage pipe maps is often privately owned and unavailable. In this study, we propose an ensemble learning approach that uses eight fully convolutional networks (FCNs), including well-known architectures such as Unet, DenseNet, and Wnet, to detect subsurface drainage pipe locations from aerial images. Each FCN model is trained and validated using an aerial image dataset, taking a 256 × 256 × 3 pixel aerial image patch as input and outputting a pixel-wise drainage pipe detection map. Weighted averaging is then applied to the individual FCN outputs to create a unified drain pipe detection map. The performance of the proposed approach is evaluated using large-scale aerial image data that has not been used during the training and validation phases. The results demonstrate that the proposed approach provides accurate and more robust drain pipe detection over the case of using an individual FCN model. We further explore the effects of image resolution for the effective use of the proposed drain pipe detection approach. • Our ensemble learning method detects subsurface pipes accurately and robustly. • The ensemble model outperforms image processing and single machine learning models. • An optimal resolution can enhance the performance of the ensemble learning model. [ABSTRACT FROM AUTHOR]

Smoother pavement provides a comfortable, safe and economical riding experience to the public and prolongs the life of the pavement with low maintenance costs. Hence, obtaining a smooth pavement is considered a necessity by many transportation agencies around the world. In order to achieve a smooth pavement, smoothness specifications are developed. Smoothness specifications mainly consist of four parts: smoothness measuring equipment, smoothness indices and analysis method, acceptance limits, and incentive/disincentive payment schemes. This paper summarizes smoothness specifications in the United States and various countries around the world and provide an overview on the comparison of smoothness measurement. The smoothness measuring devices, indices, limits and payment schemes vary from country-to-country International Roughness Index is the most used smoothness index in the US and around the world. Inertial profilers are used to measure the pavement profile for smoothness. [ABSTRACT FROM AUTHOR]

The Energy Act of 2020 authorizes $1 billion over five years from 2021 to 2025 to support energy storage development in the United States. In addition, the Federal Energy Regulatory Commission (FERC) Orders 841 and 2222 opened the wholesale energy markets for distributed energy resources, including energy storage. The statute and orders pave the way for novel energy storage technologies to participate in electricity markets as the qualifying facilities, thereby expanding opportunities for energy storage development. However, the existing policy, legal, and regulatory regime, including these much-welcomed newcomers, fails to recognize and support the entire spectrum of benefits that some forms of energy storage create. In this paper, we focus on Pumped Underground Storage Hydro (PUSH), a variant of pumped hydro storage (PHS), which currently provides over 90% of the world's energy storage capacity. PUSH operates with the same principle as PHS; however, it is an entirely underground variant of PHS. In addition to becoming competitive in the wholesale electricity market, PUSH facilities can be developed as community infrastructure in the postindustrial landscape, particularly in abandoned underground mines. Given federal energy law and policy development, this paper identifies how communities with abandoned mines, technically feasible for PUSH facilities and operating as municipal-owned utilities or cooperatives, can participate and take advantage of federal legislation. We further look into the implications through the lens of technical, economic, and social aspects of energy justice. We consider energy justice as a conceptual framework that seeks to explain the occurrence of injustice within energy system decisions and outcomes and how policymakers can respond to these injustices. We use it as a conceptual tool for understanding policy formulation and detailing the energy system's missing ethical and justice dimension. We argue that as a technically mature technology, PUSH facilities can act as a potential means to speed up the energy transition in the United States. The federal and state law along with utility market structures are vital in shaping the potential opportunities and barriers for energy storage facilities like PUSH. We show that although it supports PUSH development, there are gaps in the current market structure, specifically in the regulatory framework, when seen through the lens of justice and valuation of just energy services. These gaps limit the realization of utility-scale energy storage technology's potential to fully contribute to a decarbonized energy system that is more resilient and more just than the incumbent system. [ABSTRACT FROM AUTHOR]