K. Arthur Endsley

Evaluation of Commercially Available Remote Sensors for Highway Bridge Condition Assessment

Improving transportation infrastructure inspection methods and the ability to assess conditions of bridges has become a priority in recent years as the transportation infrastructure continues to age. Current bridge inspection techniques consist largely of labor-intensive subjective measures for quantifying deterioration of various bridge elements. Some advanced nondestructive testing techniques, such as ground- penetrating radar, are being implemented; however, little attention has been given to remote sensing technologies. Remote sensing technologies can be used to assess and monitor the condition of bridge infrastructure and improve the efficiency of inspection, repair, and rehabilitation efforts. Most important, monitoring the condition of a bridge using remote sensors can eliminate the need for traffic disruption or total lane closure because remote sensors do not come in direct contact with the structure. The purpose of this paper is to evaluate 12 potential remote sensing technologies for assessing the bridge deck and superstructure condition. Each technology was rated for accuracy, commercial availability, cost of measurement, precollection preparation, complexity of analysis and interpretation, ease of data collection, stand-off distance, and traffic disruption. Results from this study demonstrate the capabilities of each technology and their ability to address bridge challenges.

Expanding Alaska–Canada Rail: Jointly Visualizing Revenue Freight, Development Cost, Mineral Commodity Value, and Impact of Carbon Dioxide

Recent changes in global markets have raised the value of mineral resources in northwestern Canada and Alaska. The development of these resources depends on the economics of rail infrastructure expansion. Transportation decision makers need revenue and cost assessments to plan investment in rail infrastructure. A tool based on a geographic information system was developed for mineral resource evaluation and visualization. The tool incorporated expert-augmented mineral resource data for more than 22,000 occurrences in the region. The tool included the proposed Alaska–Canada Rail Link, which would connect Alaska rail to the lower 48 states. Users selected locations of known mineral occurrences near actual or proposed rail routes and used statistical mineral deposit models to estimate resource sizes and extractable value over time by combining current or user-entered commodity prices with multimodal revenue freight volumes and optimally routed transportation costs. The tool translated the revenue scenario into likely carbon dioxide emissions according to the transport of mineral concentrates to regional and international destinations. Users could select and visualize multimodal transportation networks to understand and minimize mobile-source carbon emissions as part of their scenarios. Statistical estimates of mine capital expenditure and operating costs were also calculated according to type. The tool calculated the gross metal value of a mineral occurrence with statistical deposit models. This index was linked to the positive regional economic impact associated with the developed resource in terms of jobs, taxes and royalties, and resupply. This information helped decision makers close the loop on infrastructure investment assessments.

Melt water input from the Bering Glacier watershed into the Gulf of Alaska

The annual runoff from the melting of large glaciers and snow fields along the northern perimeter of the Gulf of Alaska is a critical component of marine physical and biological systems; yet, most of this freshwater is not measured. Here we show estimates of melt for the watershed that contains the largest and longest glacier in North America, the Bering Glacier. The procedure combines in situ observations of snow and ice melt acquired by a long-term monitoring program, multispectral satellite observations, and nearby temperature measurements. The estimated melt is 40 km3 per melt season, ± 3.0 km3, observed over the decadal period, 2002–2012. As a result of climate change, these estimates could increase to 60 km3/yr by 2050. This technique and the derived melt coefficients can be applied to estimate melt from Alaska to Washington glaciers.