Showing papers by "Ontario Ministry of Transportation published in 2000"

Preferential sorption of planar contaminants in sediments from Lake Ketelmeer, The Netherlands

Abstract: Organic carbon normalized sediment-water distribution coefficients (KOC) of a series of in situ and (mass-labeled) added chlorobenzenes, PCBs, and PAHs were determined in an aged and a more recently deposited sediment layer from Lake Ketelmeer, The Netherlands, using the cosolvent method. The resulting log KOC's for both in situ and added compounds are rather high compared to literature data (up to 9.3 for benzo[ghi]perylene), with the ones in the recently deposited layer being generally higher than those in the aged layer (up to 1.6 log units). The results do not show the well-established effects due to increased contact time of contaminants with sediments (i.e. “aging” or “slow sorption”) and indicate that after only short equilibrium times (11 days) KOC's can even be higher than after several decades of contact time in the field. In addition, distribution coefficients show a remarkable dependence on sorbate planarity, manifested by significantly different log KOC−log KOW relationships for planar (chlor...

A comparison and measurement standardisation of four in situ devices for determining the erosion shear stress of intertidal sediments

Abstract: Predictive modelling of estuarine sediment erosion and transport requires a description of the erosional properties of the bed. The two main variables of interest are the critical erosion shear stress (τcr) and the erosion rate (e). A number of different erosion devices exist to measure the erosion shear stress of intertidal sediments in situ. These devices apply different strategies to induce and measure erosion, and the area over which erosion is integrated varies greatly. In addition, the definition of erosion threshold differs between workers. This makes comparison of data collected from different devices very difficult. Four different types of erosion device, Microcosm system, In Situ Erosion Flume (ISEF), SedErode and cohesive strength meter (CSM) were used during the July 1997 EC INTRMUD Humber estuary (UK) field campaign. These devices were deployed simultaneously on the Skeffling intertidal mudflat to allow comparison of the data generated. This involved the comparison of suspended particulate matter (SPM) time series, the nature of the applied shear stress (τo) and the area over which erosion was integrated. The initial goal was to develop a standard analysis procedure for comparison of stability measurements. The erosion threshold calculated from area normalised suspended particulate matter (SPMn) time series was relatively comparable between devices especially between the Microcosm and ISEF. However, device size and natural sediment spatial heterogeneity affected the results. The erosion rate varied by orders of magnitude between the different devices. This variation seemed to be due to the considerable differences in device deployment time. In conclusion, SPM data from different devices are broadly comparable, whilst erosion rates are only comparable if the shear stress steps are of the same duration.

Albatross: multiagent, rule-based model of activity pattern decisions

Abstract: The development of ALBATROSS: A Learning-Based, Transportation-Oriented Simulation System is summarized. This activity-based model of activity-travel behavior is derived from theories of choice heuristics that consumers apply when making decisions in complex environments. The model, one of the most comprehensive of its kind, predicts which activities are conducted when, where, for how long, and with whom, and the transport mode involved. In addition, various logical, temporal, spatial, spatial-temporal, and institutional constraints are incorporated in the model. The conceptual underpinnings of the model, its architecture, the functionality of its key agents, data collection, and model performance are discussed.

Global Positioning System as Data Collection Method for Travel Research

Abstract: The technology of Global Positioning Systems (GPS) provides new ways for collecting information about travel behavior. When it is used in combination with an electronic travel diary, valuable information of high quality about travel behavior becomes available. To learn about the possibilities of this new technology, a pilot study involving 151 people was performed in the Netherlands. What makes this pilot unique is the monitoring of all modes of travel, not just travel by motorized vehicles. The findings suggest that although it is possible to monitor all travel modes, data quality differs among them. The GPS device registered nearly all car driver trips, compared to half of the tram and train trips. When trips are registered, public transport trips are registered with a higher accuracy level than car trips. For specific trips, respondents did not use the equipment because of the burden placed on them or because of a lack of time. This was especially the case for walking, cycling, public transport, shoppi...

Differential response of macrozoobenthos to marine sand extraction in the North Sea and the Western Mediterranean

Abstract: Sublittoral benthic coastal communities of the North Sea and of the Western Mediterranean were studied before and after sand extraction between 1993 and 1995 at borrow sites in Denmark, The Netherlands, and Spain. Recolonization of disturbed areas was fast owing to the rapid increase of opportunistic species. At the North Sea sites, the benthic community largely recovered within 2–4 years, whereas in Spain recovery is expected to take longer. The response of zoobenthos to sand extraction is discussed, taking into account differences in site characteristics, extraction methods, and recovery time of the habitats. The effects on the benthic community appear to be related to the physical impact on the sea floor. Small-scale disturbances in seabed morphology and sediment composition result in short-term effects on the benthic community. However, larger disturbances mainly caused by sediment composition may have a prolonged effect, particularly in low dynamic systems such as those present in the Mediterranean. 2000 International Council for the Exploration of the Sea

Incorporating Road Safety into Pavement Management

Abstract: Improving road safety through proper pavement engineering and maintenance should be one of the major objectives of pavement management systems. When pavements are evaluated in terms of safety, a number of factors related to pavement engineering properties are raised, such as pavement geometric design, paving materials and mix design, pavement surface properties, shoulder type, and pavement color and visibility. Each year there are voluminous annual reports on traffic accident statistics and discussions of such road safety issues as road safety modeling and pavement safety measurements and criteria. Although road safety may be considered a separate area, it should be incorporated into pavement management systems. The main pavement engineering relationships associated with road safety are identified, and the various aspects of road safety related to pavement management, such as pavement types, pavement surface macrotexture and microtexture, and pavement safety measurements, criteria, and evaluation methods, are discussed. A systematic approach is proposed for the coordination of pavement maintenance programs with road safety improvement and the incorporation or integration of safety management with pavement and other management systems. Finally, a list of possible remedial measures for road safety improvements associated with pavement maintenance activities is recommended.

Method for Identifying Factors Contributing to Driver-Injury Severity in Traffic Crashes:

Abstract: Numerous driver, vehicle, roadway, and environmental factors contribute to crash-injury severity. In addition to main effects, interactions between factors are very likely to be significant. The large number of potentially important factors, combined with the complex nature of crash etiology and injury outcome, present significant challenges to the safety analyst, who must select from a large number of factors and specify a comprehensive but feasible set of main factors and interactions for testing in statistical models. In addition, some factors contain a relatively large number of categories (e.g., weather conditions), and the selection of cut-off points for categorization of continuous factors may not be readily obvious (e.g., driver age). It is also important that statistical tests underlying these analyses accurately address the frequent problem of data sparseness. The development and testing of a variable-selection procedure to address each of these problems is the stated objective. Bus-involved cra...

A probabilistic (max,+) approach for determining railway infrastructure capacity

Abstract: We consider the problem of determining the capacity of a planned railway infrastructure layout under uncertainties. In order to address the long-term nature of the problem, in which the exact (future) demand of service is unknown, we develop a “timetable”-free approach to avoid the specification of a particular timetable. We consider a generic infra-element that allows a concise representation of many different combinations of infrastructure, safety systems and traffic regimes, such as mixed double and single track lines (e.g., a double track line including a single tunnel tube), and train operations on partly overlapping routes at station yards. We translate the capacity assessment problem for such a generic infra-element into an optimization problem and provide a solution procedure. We illustrate our approach with a capacity assessment for the newly built high-speed railway line in The Netherlands.

Experimental Investigation of Natural Convection in a Core of a Marine Reactor in Rolling Motion

Abstract: A series of single-phase natural circulation experiments in a simulated marine reactor mounted on a rolling bed was performed and the average Nusselt number in the core was evaluated in order to investigate effects of the rolling motion on the heat transfer in the core. Heat transfer with an upright attitude is well correlated with the Rayleigh number and is slightly lower than El-Genk's correlation. Heat transfer in the core is not affected by the inclination angle because the inclination of the present experiment is not large enough to cause any remarkable changes in the flow pattern of the core. Heat transfer in the core is enhanced by the rolling motion which is thought to cause internal flow in the core. Heat transfer during the rolling motion is correlated with the Richardson number for rolling motion, R iR , and is classified into three regimes: (1) region A (0.05

Interannual Variation of Growth Rate of Atmospheric Carbon Dioxide Concentration Observed at the JMA's Three Monitoring Stations Large Increase in Concentration of Atmospheric Carbon Dioxide in 1998

Abstract: The Japan Meteorological Agency has been monitoring carbon dioxide (CO 2 ) concentrations in the atmosphere continuously with non-dispersive infrared gas analyzers since January 1987 at Ryori, March 1993 at Minamitorishima, and January 1997 at Yonagunijima. At Ryori with our longest record, a large variation was found in CO 2 growth rate in association with significant global events such as El Nino and the eruption of Mt. Pinatubo, suggesting that global changes in the carbon cycle are closely connected with the climate. The annual growth rates in CO 2 concentration were 3.0 ppm at Ryori, 2.8 ppm at Minamitorishima, and 3.1 ppm at Yonagunijima in 1998. At Ryori and Minamitorishima, they were the largest since the beginning of measurement. It is supposed that this large growth rate is attributed to the strong El Nino event in 1997/98.

Shifting Patterns of Fuel and Wood Use by Households in Rural Zimbabwe

Abstract: A questionnaire survey of fuel and wood use was administered to approximately 1500 households in rural Zimbabwe in 1994 and repeated in 1999. The nine localities covered by the survey fell into four strata distinguished by woodland cover, distance from urban centres and whether communal or resettlement (ex-commercial farming) areas. Over time household assets increased, but incomes remained constant in all but one stratum. Simultaneously wood became scarcer according to respondents. In all four strata firewood consumption fell markedly between 1994 and 1999. This was partially, but not entirely, due to switches to other fuels, either electricity near towns or non-wood biomass fuel in deforested areas further from towns. In other areas, non-wood biomass fuels declined considerably. Kerosene use showed mixed patterns, with decreases in the numbers of consumers but increased rates of consumption. Wealthier households were more likely to use modern fuels such as kerosene for cooking, candles and electricity. ...

Determination of (mono-, di- and) tributyltin in sediments. Analytical methods

Abstract: Methods for the reliable determination of butyltin compounds in sediments are required for both national and international marine monitoring programmes. This evaluation of current commonly used approaches to the analysis identifies critical aspects of extraction, derivatisation, clean-up, separation, standardisation and detection with the objective of improving the analytical capabilities both of experienced laboratories and of those addressing the problems for the first time.

Redox processes in recent sediments of the river Meuse, The Netherlands

Abstract: Pore-water concentrations of inorganic solutes were measured at four locations in a recent sedimentation area of the river Meuse in The Netherlands. The pore-water concentration profiles were interpreted using the steady state one-dimensional reaction/transport model STEADYSED1. This model explicitly accounts for the organic matter degradation pathways and secondary redox reactions. Results show that the model reproduces the measured pore-water profiles of redox species reasonably well, although significant divergence is observed for pH. The latter is due to the absence of pH buffering by CaCO3 in the model. At all locations, methanogenesis is the major pathway of organic matter degradation below 3 cm from the sediment-water interface. However, organic matter degradation rates by methanogenesis may be overestimated, because methane ebullition is not included. Differences in profiles of redox-sensitive ions among the four locations are explained by differences in depositional conditions, in particular the sediment accumulation rate and supply of organic matter.

A Database of Historical Flood Events in the Netherlands

Abstract: The Netherlands is situated on the delta of three of Europe’s main rivers: the Rhine, the Meuse and the Scheldt. As a result of this, the country has been able to develop into an important, densely populated nation. But living in the Netherlands is not without risks. Large parts of the Netherlands are below mean sea level and water levels which may occur on the rivers Rhine and Meuse. High water levels caused by storm surges on the North Sea or by high discharges of the rivers are a serious threat to the low-lying parts of the Netherlands. Construction, management and maintenance of flood defences are essential conditions for the well-being of the population and further development of the country.

Applications of the Mild-Slope Equation to Tidal Computations in the Taiwan Strait

Abstract: Employing harmonic analysis of tidal data in the Taiwan Strait, the cross-strait tidal characteristics are completely illustrated. Based on the two dimensional mild-slope equation which can be reduced to the shallow-water wave equation, a finite element model (Tsay et al., 1989) is applied to investigate the characteristics of tides in the Taiwan Strait. The co-range and equi-phase charts of major tidal constituents, such as M2, S2, N2, and K1, are reproduced. Anomalous amplification of semidiurnal tides in the Taiwan Strait is verified. With rotation effects neglected and by applying a non-reflective condition on the open boundaries, the numerical results of phase-lag and co-range distributions show very good agreement with observed data for semidiurnal tides in the Taiwan Strait. Due to crude representation of the topography at two ends along the China coast, computed tidal distributions deviate from the observations. However, both computed amplitudes and phase-lags compare very well with observed data along the central half of the China coast.

SSR station and aircraft secondary surveillance network

Abstract: An SSR reply, which is sent out from an aircraft, is received and separated into one SSR reply to one SSR station and the other SSR reply to the other SSR station, thereby generating aircraft information of the aircraft based on one of the one SSR reply and the other SSR reply.

Pavement and bridge cost allocation analysis of the Ontario, Canada, intercity highway network

Abstract: Continuous growth of road transportation demand has resulted in soaring rates of road deterioration and maintenance costs Full road cost recovery by direct charging of road users is gaining more popularity as governments face pressure to reduce general taxes, and full road cost recovery can promote more efficient use of the road system A sound charging system requires reliable models for infrastructure deterioration and sound methodologies for cost allocation In Ontario, new pavement performance models have been recently developed with more emphasis on separating the effects of traffic from the effects of environmental forces on flexible pavements in different geographic locations The recent models and data have been used to investigate the cost implications of different vehicle configurations and road characteristics for the Ontario pavements and bridges The results are used for the allocation of costs to various users of the road system The results generally have implied that initial road design s