A conflict model and interactive simulator (FASTCARS) for predicting enroute driver behavior in response to real-time traffic condition information

This paper proposes a theoretical methodology and practical data collection approach for modeling enroute driver behavioral choice under Advanced Traveler Information Systems (ATIS). The theoretical framework is based on conflict assessment and resolution theories popularized in psychology and applied to models of individual consumer behavior. It is posed that enroute assessment and adjustment is a reactionary process influenced by increased conflict arousal and motivation to change. When conflict rises to a level at which conflict exceeds a personal threshold of tolerance, drivers are likely to alter enroute behavior to alleviate conflict through either route diversion of goal revision. Assessment and response to conflict arousal directly relate to the driver's abilities to perceive and predict network conditions in conjunction with familiarity of network configurations and accessible alternate routes.Data collection is accomplished through FASTCARS (Freeway andArterialStreetTrafficConflictArousal andResolutionSimulator), in interactive microcomputer-based driving simulator. Limited real-world implementation of ATIS has made it difficult to study or predict individual driver reaction to these technologies. It is contended here that in-laboratory experimentation with interactive route choice simulators can substitute for the lack of real-world applications and provide an alternate approach to data collection and driver behavior analysis. This paper will explain how FASTCARS is useful for collecting data and testing theories of driver behavior.     

Reconsidering the multinomial probit model

Recently developed computational methods have greatly reduced the difficulty of estimating multinomial probit models and may soon make multinomial probit a computationally feasible option in applied travel demand modeling. This paper discusses some of the benefits and costs that are associated with the use of multinomial probit in demand modeling. It is argued that although there are situations in which multinomial probit is essential for achieving a satisfactory model, most problems with existing demand models are unlikely to be mitigated by the use of multinomial probit.     

Jack-up conversion for production

For the production development of marginal offshore oil fields or to achieve early production in offshore fields scheduled for full production facilities a jack-up drilling rig can be converted to operate as a mobile production unit. This paper presents a summary discussion of the main aspects to be considered in the design, conversion, installation and operation of a jack-up production unit.     

Size-fractionated phytoplankton biomass and species composition in the Indian sector of the Southern Ocean during austral summer

During the late austral summer of 1994, Antarctic waters were characterized by low phytoplankton biomass. Along the 62°E meridian transect, between 49°S and 67°S, chlorophyll (Chl.) a concentration in the upper 150 m was on average 0.2 mg m⁻³. However, in the Seasonal Ice Zone (SIZ) chlorophyll a concentrations were higher, with a characteristic deep chlorophyll maximum. The highest value (0.6 mg Chl. a m⁻³) was measured at the Antarctic Divergence, 64°S, corresponding to the depth of the temperature minimum (100 m). This deep biomass maximum decreased from South to North, disappeared in the Permanently Open Ocean Zone (POOZ) and reappeared with less vigour in the vicinity of the Polar Front Zone (PFZ). In the SIZ, the upper mixed layer was shallow, biomass was higher and the >10 μm fraction was predominant. In this zone the >10 μm, 2–10 μm and <2 μm size fractions represented on the average 46%, 25.1% and 28.9% of the total integrated Chl. a stock in the upper 100 m, respectively. The phytoplankton assemblage was diverse, mainly composed of large diatoms and dinoflagellate cells which contributed 42.7% and 33.1% of the autotrophic carbon biomass, respectively. Moving northwards, in parallel with the decrease in biomass, the biomass of autotrophic pico- and nanoflagellates (mainly Cryptophytes) increased steadily. In the POOZ, the picoplanktonic size fraction contributed 47.4% of the total integrated Chl. a stock. A phytoplankton community structure with low biomass and picoplankton-dominated assemblage in the POOZ contrasted with the relatively rich, diverse and diatom-dominated assemblage in the SIZ. These differences reflect the spatial and temporal variations prevailing in the Southern Ocean pelagic ecosystem.     

Lateral Stability of Towed Flexible Vehicles

The highway transport of mobile homes is a matter of concern for the increasingly safety-minded driving public. The low speeds of towed vehicles necessary to maintain stability, together with the requirements for excessive lane widths due to clearance for the lateral motion, result in increased likelihood of traffic accidents, impeded traffic flow, and reduced highway capacity. A safe increase in the stable cruising speed, coupled with a decreased amplitude in the pendular motion helps alleviate all three of the aforementioned problems. Energy input at hitch point and lateral forces between the road and tires permit lateral vehicular motions, which occur above a critical speed, to increase in amplitude until possibly a limit cycle or instability is reached. One would expect that structural dynamics could have a pronounced influence on the lateral response of towed vehicles with large and relatively flexible chassis, such as mobile homes. The objective of this research is to determine the influence of chassis structural parameters on the lateral stability of towed flexible bodies during transport. The mass of the towing vehicle is assumed infinitely large, thus eliminating any dynamic interconnection between the towing and towed vehicles. The assumed modes method is used to describe the lateral deflection of the flexible towed vehicle. Results of the study of this model indicate that increase in structural rigidity of towed vehicle increases the critical towing speed whereas increase in the tire cornering coefficient reduces the safe towing speed, which is true only for this simplified model where the dynamic interaction with the towing vehicle is not included.     

Meroplankton abundance in the Northeast Water Polynya: Insights from oceanographic parameters and benthic abundance patterns

We investigated meroplankton (planktonic larvae of benthic organisms) abundance and distribution in the Northeast Water (NEW) Polynya, located on the northeast coast of Greenland, from July 15 to August 15, 1992. Meroplankton was present at all sites visited (0.03–84.83 individuals per m³); at one station meroplankton comprised 8.28% of total zooplankton. Total meroplankton abundance was correlated with total zooplankton abundance and total benthic infaunal abundance but was not correlated with either microscopic carbon concentration or primary productivity. Examination of distribution data for barnacle nauplii and adults indicated that both adults and larvae were concentrated at the same locations. Patterns of distribution were also examined for stelleroid plutei, polychaete larvae and trochophores. There were distinct geographic patterns in total and class-specific meroplankton distributions, with maximal abundances occurring over the Belgica Bank and in the eastern regions of the Westwind Trough and minimal abundances in the Belgica Trough. The apparent control of meroplankton distribution by the hydrography of the region, coupled with the correlation between meroplankton, zooplankton and adult infaunal abundance, reinforces the hypothesis that hydrography plays a major role in controlling the distribution of biota in the NEW polynya (Ambrose and Renaud, 1995; Ashjian et al., 1995, 1997-this volume; Smith et al., 1995; Piepenburg et al., 1997-this volume).     

Life cycle of Epischura baicalensis Sars (Copepoda, Calanoida) in Lake Baikal

Epischura baicalensis Sars is a dominant pelagic species of Lake Baikal zooplankton. This is endemic to Lake Baikal and inhabits the entire water column. It produces two generations per year: the winter–spring and the summer. These copepods develop under different ecological conditions and vary in the duration of life stages, reproduction time, maturation of sex products and adult males and females lifespan. The total life period of the animals from each generation is one year. One female can produce 10 egg sacks every 10–20 days during its life time. The ratio of males and females is 1:1. One of the most essential features of the ecology of E. baicalensis is the alteration of its mass inhabited areas during a year, as well as in day time. This is due to the need for various conditions for gonad maturation, reproduction, nourishing and protection from being consumed by planktivors.     

Analyzing the preference for non-exclusive forms of telecommuting: Modeling and policy implications

This study examines three models of the individual's preference for home- and center-based telecommuting. Issues concerning the estimation of discrete models when the alternatives are non-exclusive are discussed. Two binary logit models are presented, one on the preference to telecommute from a center versus not telecommuting from a center (adjusted ² = 0.24), and the other on the preference to telecommute from a center over telecommuting from home (adjusted ² = 0.64). A nested logit model is also estimated on the following four alternatives: preferring not to telecommute, preferring either form of telecommuting, preferring to telecommute from home, and preferring to telecommute from a center (adjusted ² = 0.35).The results of the models illustrated the importance of attitudinal measures in measuring an individual's preference to telecommute. Oblique factor scores representing workplace interaction, stress, workaholism, internal control, and commute stress were statistically significant in some or all of the models. Other explanatory variables which were found to be consistently significant were education, job suitability, and age. Most respondents preferred either to telecommute from home or were indifferent between either form of telecommuting, which raises the question as to whether there really is a sizeable market niche to be filled by telecommuting centers, and hence whether they may make a significant contribution to transportation demand reduction.     

Evaluating marginal improvements to a transport network: An application to the Santiago underground

This paper describes a simplified methodology designed for quick investment appraisal of improvements to a transport network, and discusses its limitations and advantages particularly in the context of a developing country. The approach basically considers:

- a method to define the total population (relevant origin-destination pairs) affected by the project

- the selection of a low-cost background model to represent transport demand on a network at an aggregate level

- the choice of a suitable marginal demand model (in this case a discrete mode choice model) capable of providing the required sensitivity and accuracy to model the project

- the estimation of the marginal demand due to the project during all the years of the study horizon, and

- a sensitivity analysis to assess the robustness of the decision recommended using these two models.

Finally, the paper summarises the results of applying the methodology to the case of an extension to the Santiago underground; it was found that the project has a high social rate of return (almost 20 per cent). However, from the point of view of a private evaluation, it can cover its operating costs only.