GENERALIDADES DE CULTIVO DE MAÍZ

Problem description

A very basic consideration for any monitoring system is precisely what behaviors should be monitored. The literature search conducted during the present project (Section 2.2) revealed a sizable set of candidate driver behaviors that are potentially related to teen driver crashes and/or appear to be viable candidates for use in monitoring systems. Multiple candidate behaviors were found under each of various broad categories, such as vehicle control behaviors, risky/aggressive driving acts, in-vehicle activity, visual search, physical status, and trip features. This same literature, however, was quite lacking in providing a good empirical basis for selecting a specific set of behaviors for use in monitoring systems. The teen driver naturalistic driving study (Section 5.0) is not fully analyzed at this point, and may provide some additional insights. Basically, however, we are at a point where a case can be made for many possible teen driver measures, but there is little basis for objective choices. Decisions need to be made regarding both the behaviors that are directly sensed by the system and the descriptive or summary information that is

provided as feedback to the driver, parent, or other involved party.

In expert discussion during the 2008 workshop on novice teen driver monitoring, two general philosophies regarding behaviors to monitor were expressed by participants. Some argued that systems should be kept simple. A few basic measures that are obviously related to risky driving, such as speeding and braking, will presumably provide an adequate basis for monitoring and would yield a simple and interpretable outcome for reporting. Others argued that a more comprehensive set of monitored behaviors may produce a greater influence on driver behavior and that the question of what best to monitor is an empirical one. There was also debate over the need to detect and incorporate aspects of the driving context into the monitoring system. For example, should speed feedback take account of the speeds of surrounding traffic, should

tailgating definitions reflect traffic density, or should the presence of teen passengers modify the system response? There was no consensus or resolution of these questions at the workshop. The question of the “best” behaviors to monitor also depends on the criteria for selection.

Monitoring aspects that modify teen driver behavior most during the period that monitoring is in effect may not necessarily be the same ones that best maintain performance over the longer term. For example, speed reporting might limit risky behavior most during monitoring, but might have no lasting effect, whereas coaching feedback based on hard deceleration events might result in fewer crashes after the monitoring period ends. Furthermore, the monitored acts that are most effective for use in modifying teen driver behavior are not necessarily the best indices to use in measuring system safety benefits. For example, perhaps speed reporting changes behavior most, but the frequency of hard braking events is a more sensitive measure of crash likelihood than is speed. Thus we might choose one behavior to monitor for use as feedback and another behavior to monitor as an outcome performance measure. Some outcome measures might require sensors or recording in addition to those used for monitoring (e.g., forward radar to measure headway and time-to-collision). While these are hypothetical examples, they illustrate the point that there

66

are multiple criteria that may be used in selecting alternative driver behaviors to monitor. In addition, alternative behaviors may vary in practical considerations such as the cost of sensors, reliability, sensitivity, susceptibility to system defeat, and so forth.

Research objective

The intent of this project is to provide an objective basis for the choice of behaviors and

situations to monitor, as well as the conditions and behaviors that warrant reporting or feedback. The goal is not necessarily to define a single “best” behavioral set, but rather to determine the relative benefits of various alternative or additional behaviors. The ultimate choices for actual use in monitoring systems and programs may depend on product-specific considerations, such as target drivers, target consumers, cost, program aspects, and so forth. The project should provide a comparison of alternatives so that system designers know which behaviors provide an adequate basis for a monitoring system, which are most effective in influencing behavior, what added benefits come from expanding the set of monitored behaviors, and what measures are good indices of actual safety benefits.

Approach/anticipated methods

The project should involve both analytic activities and new empirical data collection. It is evident that the very extensive list of potential behaviors is longer than can be incorporated into any practical research study. Initial project activity to identify promising alternatives may take advantage of existing resources. These include major crash data base analyses, meta analyses or other procedures for assessing monitoring studies to date (of which a number are currently in process), and focused analyses of existing data from naturalistic driving studies. The teen naturalistic driving study (Section 5.0) will be one such source. Others may include the currently-planned large scale naturalistic study to be conducted under the SHRP 2 program, which may or may not be available within the time frame of this effort. Other naturalistic studies or field operational tests may not include teen drivers but may suggest the relative sensitivity of alternative measures. The various analytic activities should be used to derive a smaller set of alternatives for the empirical research.

Empirical data collection should involve experimental manipulation of the monitored behaviors. Some data collection will need to be done using actual teen drivers, but it may also be possible to conduct some of this work in extended simulator driving environments. It may also be possible to use within-subjects designs for greater efficiency. As noted, it would be valuable to assess alternatives not only for their effectiveness while the monitoring program is in effect, but also for longer lasting effects on driver performance, once the monitoring has ceased. The longer term effects will be more difficult to assess in a practical manner. Therefore it is assumed that the study will focus primarily on the evaluation of behavior during the monitoring period, but that some resources should be dedicated to the longer term effects, for a selected subset of behaviors. Potential benefits/payoff

This study will provide a fundamental piece of knowledge for effective monitoring system design that is unlikely to be derived from more piecemeal efforts in individual system development. It should permit systems to be optimally effective without being overly burdensome or expensive. Therefore there should be benefits both in terms of system effectiveness and in terms of consumer use and public acceptance.

6.3.4 Research study: Design for family use of monitoring systems