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From page 110...
... 110 Chapter 10. Safety Framework to Assess the Impact of Highway Signs on Distraction Using Simulator Data 10.1 Introduction 10.1.1 Background An important challenge arises when law enforcement reports or other naturalistic data sources are used to evaluate the distraction potential of external objects: individual events (such as crashes or NC occurrences)
From page 111...
... 111 • How does OVD vary between nighttime and daytime driving? • What variables (e.g., steering wheel position, glance location, glance duration)
From page 112...
... 112 For the study that produced the IMPACT database, the cab was equipped with a Face Lab 5.0 eye tracking system (developed by Seeing Machines, Canberra, Australia) that was mounted on the dash above the steering wheel, as shown in Figure 25.
From page 113...
... 113 Participants drove a scenario representative of a drive home from an urban area for a total drive time of approximately 35 minutes. The drive started with an urban segment composed of a twolane roadway through a city with posted speed limits of 25 to 45 mph with signal-controlled and uncontrolled intersections.
From page 114...
... 114 Table 13. External roadway features included in analysis.
From page 115...
... 115 10.2.3 Roadway Elements Considered but Not Included As part of the video review, other segments of the drive and other external features were considered for inclusion in the analysis. Specifically, the urban segment of the drive contained many external features that might capture a driver's attention (Figure 28)
From page 116...
... 116 box for a feature were an indicator that the driver looked at that feature. Gaze pitch and yaw angles that corresponded to glances at the feature were determined, and gaze locations were tracked to estimate the occurrence and duration of each glance.
From page 117...
... 117 performance measures between the event and baseline epochs. These analyses are described in detail below.
From page 118...
... 118 Figure 30. Average glance time across the external features, with points representing individual drivers.
From page 119...
... 119 Again, the point of reference for classifying distraction was long periods of eyes-off-road time. Drivers who glanced toward the external features in this data set clearly fell below this off-road glance threshold.
From page 120...
... 120 effect "tunnel vision," when drivers are distracted. This could lead to drivers missing critical information in the driving scene (Figure 32)
From page 121...
... 121 Figure 33. PRC gaze for the route sign before the exit event.
From page 122...
... 122 highway exit sign. Horizontal gaze dispersion was statistically different for all of the features except billboards.
From page 123...
... 123 While the data set for this analysis ultimately included data from an Interstate segment only, the initial plan was to examine other aspects of the study drive, including an urban segment with unique signs and roadway features. For the reasons mentioned earlier in this chapter, however, it was determined that the analysis undertaken for this Safety Framework was not feasible for those sections of the drive.
From page 124...
... 124 features evaluated in this analysis were all common roadway signing. The results indicate that there was some evidence, although limited, of visual distraction due to the five roadway features included in the analysis.

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