Comparative evaluation of microscopic car-following behavior

Microscopic traffic-simulation tools are increasingly being applied to evaluate the impacts of a wide variety of intelligent transport, systems (ITS) applications and other dynamic problems that are difficult to solve using traditional analytical models. The accuracy of a traffic-simulation system depends highly on the quality of the traffic-flow model at its core, with the two main critical components being the car-following and lane-changing models. This paper presents findings from a comparative evaluation of car-following behavior in a number of traffic simulators [advanced interactive microscopic simulator for urban and nonurban networks (AIMSUN), parallel microscopic simulation (PARAMICS), and Verkehr in Statiten-simulation (VISSIM)]. The car-following algorithms used in these simulators have been developed from a variety of theoretical backgrounds and are reported to have been calibrated on a number of different data sets. Very few independent studies have attempted to evaluate the performance of the underlying algorithms based on the same data set. The results reported in this study are based on a car-following experiment that used instrumented vehicles to record the speed and relative distance between follower and leader vehicles on a one-lane road. The experiment was replicated in each tool and the simulated car-following behavior was compared to the field data using a number of error tests. The results showed lower error values for the Gipps-based models implemented in AIMSUN and similar error values for the psychophysical spacing models used in VISSIM and PARAMICS. A qualitative drift and goal-seeking behavior test, which essentially shows how the distance headway between leader and follower vehicles should oscillate around a stable distance, also confirmed the findings.

Clinical supervision in school counselling and career counselling: Is it time to develop a new story?

Supervision provides benefits for school counsellors and career counsellors such as support, an opportunity to gain new ideas and strategies, and personal and professional development. Despite this, studies have also shown that school counsellors perceive that the amount of time they participate in supervision is inadequate. In career counselling, there is little evidence that supervision has even been established as a mainstream professional practice. The reasons for this curious situation, whereby little time is spent on a potentially beneficial activity, are uncertain. The present study investigated the supervisory experiences of a group of school counsellors and career counsellors for a six month period following their completion of an intensive supervision training program. Participants recorded their supervisory experiences in a structured diary. Even though the participants were well informed about supervision, the findings of the present study are consistent with those of previous studies. This history of repeatedly similar findings suggests that it may be timely to ask some fundamental questions about supervision in these two professions. Such questions in turn suggest possible new research directions.

Media constructions of the Schapelle Corby trial

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