Quantifying anthropogenic shoreline modification of the Hudson River and Estuary from European contact to modern time

Abstract

Anthropogenic modifications to the shoreline of the New York Harbor estuary and the tidal portion of the Hudson River have been mapped and quantitatively assessed. Modifications studied include the filling of tidal salt‐ and freshwater marshes and the creation of fast land as well as dredging, shoreline armoring, and dike installation. Because the Hudson Estuary and River comprise a historically and commercially important harbor and waterway, shoreline modification commenced shortly after European colonization. While in the harbor segment of the estuary only about 20% of the original wetland areas remain today, the tidal Hudson River has seen a net increase in tidal freshwater wetland area of about the same magnitude resulting principally from shoreline railroad construction. Several different methods were used in compilation of the historical shoreline. Because determination of historical shorelines is important to public trust lands and to estuarine rehabilitation, data bases are being constructed incorporating those shorelines. The experience of this project suggests the benefits and problems associated with the techniques used.     

Ocean energy—an update

The oceans of the world, which comprise 71% of the earth's surface, provide a vast resource of renewable energy which has only been used in limited quantities. The feasibility of the extraction of energy from the ocean has been discussed and deemed possible, but with very few successful applications. However, as the world energy and economic situation changes, many countries are initiating R&D programmes to use the ocean waves, tides, currents, and temperature differentials to produce electricity. The transmission and utilization of this oceanderived electricity requires the integration of an ocean facility into an existing land-based electric power transmission grid. Extensive use of this energy source is still years in the future; however, prototype systems have been and are being developed so that this limitless supply can be successfully tapped.     

Development of simplified analytical methods for predicting the response of offshore structures to blast and fire loading

This paper discusses structural response to blast loading and temperature changes in fires. Both extreme events can be modelled using a range of analytical techniques from simple methodologies to the very complicated finite element analysis. The relatively simple techniques are appropriate for this type of problem and degree of accuracy required given the level of uncertainty in the loading. Given specific boundary conditions and physical properties, the methodologies proposed in the paper provide as good estimates of the dynamic response to blast loading and temperature increases in fires as the more sophisticated finite element method. Experimental data compares well with the analytical results.     

Suburban service in North America today—Which way will we go?

The current situation of suburban rail services is reviewed. Differences between seemingly similar services—urban transit, commuter service, suburban rail service and regional rail -are discussed. The suburban rail commuter is described as the true intermodal traveler. Differences of the political backgrounds of the inner-city compared to the suburbs complicate implementation of programs to improve service and suggest deep problems over the long term. Because the transition of suburban rail service from the private to public sector has been so recent, it is difficult for many to recognize that the profit of the service is in the lower total transportation costs for the community as compared to a cash dividend. Existing railroad lines in many cities have the potential of being a cost-effective solution to traffic problems, although the specific solutions vary widely, ranging from the operation of new commuter trains over the lines of a heavy duty railroad (Toronto) to a completely new light rail system (San Diego).     

What Does Happen to Our Driving When We Get Older?

Abstract

The objective of this paper is to uncover the main antecedents associated with driving errors among older drivers in order to establish a framework for analyzing potential skill improvements using other approaches, for example, games. The article also aims at classifying age-related declines in seniors' abilities associated with their driving performance. The research undertakes an analysis of attempts made through the investigation of the literature. We have systematically searched papers and extracted (1) prevalent driving errors among seniors and (2) underlying age-related declines in seniors' abilities associated with their driving performance. We have also identified some characteristics of the research in this area (e.g. the research methods and geographical distribution of the research). Our expert panel mapped the functional declines in seniors' abilities to the driving errors to identify the relationship between these findings. A reliability test resulted in 81% reliability of findings. We have identified eight groups of driving errors, which could be affected by physical, visual, and cognitive declines among seniors. According to the experts' opinions, the underlying relationship of physical, visual, and cognitive declines among seniors and their driving errors were also presented. Our findings show that there is a potential for the use of innovative interventions such as playing video games to create an inexpensive, motivational, and enjoyable method that may provide a transfer effect to specific driving skills. This could help improve seniors' driving performance by improving specific functional abilities associated with driving.     

Examining the effect of speed,roadside features,and roadway geometry on crash experience along a rural corridor

This paper presents a current investigation into crash experience along a 15.7-mile rural corridor in southwest Montana with the aim of better understanding crash causal factors along the corridor. The study utilized ten years of crash data, geometric data, and observed freeflow speed data along the corridor. A systematic approach was used where every tenth of a mile was described in term of the crash experience, speed, alignment, and roadside features. Using bivariate and multivariate statistical anal-yses, the study investigated the crash experience along the corridor as well as some of the underlying relationships which could explain some of the crash causal factors. Results show a strong association between crash rates and horizontal curvatures even for flat curves that can be negotiated at speeds above the posted speed limit, per the highway design equations. Higher crash rates were also found to be associated with the difference between the observed free-flow speeds and the speed dictated by the curve radius or sight distance as per the design equations. Further, results strongly support the safety benefits of guardrails as evidenced by the lower crash rates and severities. The presence of fixed objects and the steepness of side slopes were also found to have an effect on crash rates and severities.     

Modal split models based on car availability: the application of such models in studies of medium sized towns

This paper discusses the need for a new approach to urban transportation modelling in recognition that at least in medium sized towns the choice of model is largely dominated by car availability.     

Bond Graphs, Normal Modes and Vehicular Structures

Bond graph modeling techniques are used to represent the normal mode dynamic behavior of uniform Bernoulli-Euler beams. The independent beam models are then coupled together to form a distributed system structure of arbitrary complexity. The resulting overall system bond graph is shown to yield the governing state equations in a straightforward manner. Then, through proper ordering of the equations, the normal modes and frequencies of the coupled system are easily obtained

This procedure is demonstrated for a vehicle A-frame structure. In addition, the bond graph model is modified to include primary and secondary suspension dynamics.     

Unlimited Access

Universities and public transit agencies have together invented an arrangement – called Unlimited Access – that provides fare-free transit service for over 825,000 people. The university typically pays the transit agency an annual lump sum based on expected student ridership, and students simply show their university identification to board the bus. This paper reports the results of a survey of Unlimited Access programs at 35 universities. University officials report that Unlimited Access reduces parking demand, increases students' access to the campus, helps to recruit and retain students, and reduces the cost of attending college. Transit agencies report that Unlimited Access increases ridership, fills empty seats, improves transit service, and reduces the operating cost per rider. Increases in student transit ridership ranged from 71 percent to 200 percent during the first year of Unlimited Access, and growth in subsequent years ranged from 2 percent to 10 percent per year. The universities' average cost for Unlimited Access is $30 per student per year.