Assessment of climate change adaptation costs for the U.S. road network

The U.S. road network is one of the nation's most important capital assets and is vital to the functioning of the U.S. economy. Maintaining this asset involves approximately $134 billion of government funds annually from Federal, State, and local agencies. Climate change may represent a risk or an opportunity to this network, as changes in climate stress will affect the resources necessary for both road maintenance and construction projects. This paper develops an approach for estimating climate-related changes in road maintenance and construction costs such that the current level of service provided by roads is maintained over time. We estimate these costs under a baseline scenario in which annual mean global temperature increases by 1.5 °C in 2050 relative to the historical average and a mitigation scenario under which this increase in mean temperature is limited to 1.0 °C. Depending on the nature of the changes in climate that occur in a given area, our analysis suggests that climate change may lead to a reduction in road maintenance and/or construction costs or an increase in costs. Overall, however, our analysis shows that climate change, if unchecked, will increase the annual costs of keeping paved and unpaved roads in service by $785 million in present value terms by 2050. When not discounted, this figure increases to $2.8 billion. Policies to reduce greenhouse gas emissions are estimated to reduce these costs by approximately $280 million in present value terms and by $885 million when not discounted. These costs vary substantially by region and time period, information that should be important for transportation planners at the national, state, and local levels.     

Enhancing the durability of flooded low-capacity soils by utilizing lime-activated ground granulated blastfurnace slag (GGBS)

Flooding has a significant impact on road infrastructural development and maintenance. This study was aimed at mitigating the effects of flooding of low-bearing capacity soils, a solution that could alleviate the effects of flooding on road structural layers, especially, those constructed on flood susceptible soils and/or regions. The achievement of such an improvement would foster the growth of road infrastructural development, particularly for low income economies where critical savings accruing from this mitigation effect could be invested in further development projects.Laboratory simulation of flooding was carried out on stabilized soil test specimens. The production of the test specimens involved the use of Lower Oxford Clay (LOC) as a typical low-bearing capacity soil, stabilized using varying proportions of a latently hydraulic industrial by-product material – Ground Granulated Blastfurnace Slag (GGBS) – blended with quicklime (CaO) as an activator. Reducing the use of lime by incorporating GGBS enhances sustainability of the proposed process. Cylindrical test specimens of 50 mm in diameter and 100 mm in height were statically compacted to achieve maximum dry density (MDD), prior to moist curing for varying time periods before simulating prolonged flooding. Water absorption was monitored during the flooding process, and the specimens then tested for compressive strength. The results suggest potential of these lime–GGBS–LOC mixtures in overcoming the deleterious effect of flooding, by reduced water absorption and maintenance of a rigid cementing matrix structure after prolonged flooding. This is believed to offer savings from the improved robustness of road structural layers upon flooding, through resource conservation and material durability enhancement.     

Long-term changes in the seasonality of selected diatoms related to grazers and environmental conditions

The decoupling of trophic interactions could be one of the severe consequences of climate warming in aquatic systems. The timing of phytoplankton blooms, in particular, can affect competition within the plankton community as well as food-web interactions with zooplankton and fish. Using long-term data from Helgoland Roads in the southern North Sea, we examine diatom seasonality, using three representative diatom species combined with environmental and copepod time series over the last four decades. The long-term annual abundances of Guinardia delicatula, Thalassionema nitzschioides and Odontella aurita exhibited interannual variations and dissimilar cyclic patterns during the time period under study (1962-2008). Of the three diatoms, G. delicatula showed a significant trend towards earlier bloom timings for 1962-2008 and a later decline of its abundance over time was found. Grazing and water transparency explained most of the bloom timing fluctuations of the diatoms considered. The annual timing of occurrences of each diatom species was correlated with their preceding concentrations. Earlier bloom timings occurred when autumn/winter concentrations were higher than average and later bloom timings occurred when autumn/winter concentrations were lower than average. Different environmental and predation variables related to the diatom bloom timings were found suggesting that climate warming might not affect the onset of the blooms of the three diatom species in the same manner. The results of the multiple linear regression analyses showed that the timings of decline of the three diatoms were mainly correlated with decreasing nutrient concentrations. Sunshine duration could prolong the duration of the blooms of T. nitzschioides and O. aurita provided that enough nutrients were available. In the case of G. delicatula, however, sunshine duration was negatively correlated with its end of the growth period. G. delicatula and T. nitzschioides showed later decreases in abundances under warmer spring and summer temperatures. Such species specific differences in the sensitivity to the forcing variables could lead to shifts in community structure and could ultimately have wider implications to the overall ecosystem health of the North Sea.     

Transportation costs and the spatial distribution of land use in the Brazilian Amazon

We examine the question of whether reducing transport costs in the Amazon has lead to increased land clearing. Data on land clearing, transport costs and other related variables from 1975 to 1995 is analyzed using econometric approaches that exploit the dynamic time series dimension of the data to control for possible omitted variables and endogeneity. Our results suggest that the impact of changes in transport costs on clearing depends greatly on the initial land use. Specifically, we find that in regions where a greater proportion of the land is already cleared, reducing transport costs can lessen the rate of future clearing. On the other hand, reducing transport costs through areas that have seen little human activity is more likely to increase deforestation.     

Trends in landslide occurrence in Nepal

Nepal is a mountainous, less developed kingdom that straddles the boundary between the Indian and Himalayan tectonic plates. In Nepal, landslides represent a major constraint on development, causing high levels of economic loss and substantial numbers of fatalities each year. There is a general consensus that the impacts of landslides in countries such as Nepal are increasing with time, but until now there has been little or no quantitative data to support this view, or to explain the causes of the increases. In this paper, a database of landslide fatalities in Nepal has been compiled and analysed for the period 1978–2005. The database suggests that there is a high level of variability in the occurrence of landslides from year to year, but that the overall trend is upward. Analyses of the trends in the data suggest that there is a cyclicity in the occurrence of landslide fatalities that strongly mirrors the cyclicity observed in the SW (summer) monsoon in South Asia. Perhaps surprisingly the relationship is inverse, but this is explained through an inverse relationship between monsoon strength and the amount of precipitation in the Hill District areas of Nepal. It is also clear that in recent years the number of fatalities has increased dramatically over and above the effects of the monsoon cycle. Three explanations are explored for this: land-use change, the effects of the ongoing civil war in Nepal, and road building. It is concluded that a major component of the generally upward trend in landslide impact probably results from the rural road-building programme, and its attendant changes to physical and natural systems.     

Railroads, roads and lateral disconnection in the river landscapes of the continental United States

Railroads and roads are ubiquitous features in the river corridors of the United States. However, their impact on hydrologic, geomorphic, and ecological processes in fluvial and riparian landscapes has not been systematically explored at regional or continental extents. This study documents the geographic distribution of roads and railroads in the alluvial floodplains of the continental United States and the regional variability of their potential impacts on lateral connectivity and resultant channel and floodplain structure and function. We use national scale data sets and GIS analysis to derive data on stream–transportation network interactions in two broad categories: (1) crossing impacts, such as bridges and culverts, and (2) impacts where transportation infrastructure acts as a longitudinal dam along the stream channel, causing lateral floodplain disconnection. Potential stream crossing impacts are greatest in regions with long histories of road and railroad development and relatively low relief, such as the Mid-Atlantic, New England, and the Lower Mississippi and Ohio Valleys. Potential lateral disconnections are more prevalent in rugged regions such as the Western U.S. and Appalachians where transportation routes follow river corridors along valley bottoms. Based on these results, we develop a conceptual model that suggests that the area of lateral disconnection due to transportation infrastructure should be most extensive in mid-sized alluvial valleys in relatively rugged settings. The result of this disconnection is the disruption of the long-term, cut-and-fill alluviation and of the shorter-term flood and flow pulse processes that create and maintain ecosystem function in river landscapes. The tremendous extent of transportation infrastructure in alluvial valleys documented in this study suggests a revision to H.B.N. Hynes' statement that the valley rules the stream. Instead, it appears that in modern landscapes of the U.S. the valley rules the transportation network — and the transportation network rules the stream.     

The roads of the Sayan Mountains: Theorizing remoteness in eastern Siberia

The Sayan crossroads is a distinct cultural and economic region in the mountains of eastern Siberia. It spans three federal units in the Russian Federation: the national republics of Tyva (Todzha kozhuun) and Buryatia (Okinskii raion), as well as Irkutsk oblast (Tofalarskoe municipality). Attempts at integration by the state during the Soviet period and afterwards have privileged the construction of roads in a variety of forms to connect these areas economically with regional centers and, in turn, the rest of the country. Yet this process has been uneven and led to divergences in the economic regimes in each of the three regions that make up the crossroads. The evolution of subsistence economies, exploitation by extractive industries, and the development of tourism as an alternative source of income all differ across the three federal subunits. In turn, these divergences within the crossroads as a region point to variation in the condition of remoteness. Remoteness is an instance of relative immobility, determined by physical geography, environment, and ethnicity. And remoteness influences the function that roads play in integrating state spaces both economically and politically. In turn, this article argues for the foregrounding of the remote in the literature on mobilities in human geography, considering what the condition of remoteness allows for and forecloses in the articulation of state power and the integration of hard-to-reach areas.     

一种新型的公路核子检测仪

本文介绍了一种基于康谱顿背散射扫描（ＣＢＳ）的新型的公路核子检测仪的主要特点,软件流程框图和数据处理的基本算法。     

Regional integration or disintegration? Recent road improvements in Petén, Guatemala: A review of preliminary economic, agricultural, and environmental impacts

Many studies have examined the impacts of new roads in tropical forest frontiers. In general, these have led to substantial deforestation because they provide access to peasant farmers in need of land for food production and income generation. But few studies have investigated the impacts of improvements made to existing roads in frontier regions, and more specifically, their effects on the rural economy, land use, and land cover. This paper discusses the results of a 2001 study of these impacts, following the recent paving of the main road between Petén, a lowland frontier region in northern Guatemala, and the more densely populated highland regions of the country. This improvement, completed in late 1999, has yielded a major reduction in travel time between Flores, Petén and Guatemala City, the capital, from 12 to 14 h, or more, previously, to 7-8 h currently. The effects of this substantial change were examined through interviews and discussions with farmers, market vendors, and representatives of governmental and non-governmental organizations in the region, and through analyzing the limited available data on imports to Petén from other parts of the country. The results indicate that to date, the farmers in the study area have not altered their land use patterns because the prices they receive from intermediaries have not changed, and no market for new crops has emerged. However, more agricultural products raised in other regions of Guatemala are now being sold in Petén. Therefore, producers in Petén seemingly face greater competition from those elsewhere in the country. This trend has important implications regarding the impacts of regional integration, and for the difficult challenge of improving agricultural and environmental conditions in Petén.