The Effects of Commercial Electronic Variable Message Signs ...

5.0 FUTURE RESEARCH PROGRAM
As stated previously, it is not possible to answer all of the critical questions concerning possible
attention, distraction, and safety impacts from CEVMS in a single experiment. Instead, a
carefully crafted program of research needs to be conceived and implemented to embrace a series
of interrelated experiments and studies directed at answering different facets of this complex
issue. This section describes the important elements of a recommended research program. This
research program is broadly defined to provide a background and context for more concrete
alternative first stage studies outlined in section 6.0. This section describes a long-range
multistudy research program covering a number of years. Section 6.0 will outline three methods
for implementing the first stage of that program.
5.1 STAGES
The proposed research program would have the following three stages:
• Stage 1—The attention and distraction effects of CEVMS would be investigated to
determine whether any observed or measured distractions due to CEVMS is sufficient to
interfere with attentional criteria for safe driving. This stage is directed at discovering
whether or not distraction from CEVMS represents a potential driving hazard. Initial
CEVMS parameters must be chosen carefully so as not to bias the result from the outset.
• Stage 2—If potential interfering distraction is observed, it would be necessary to
investigate the relationship between the observed distraction and various CEVMS
parameters (e.g., luminance, change rate, distance, CEVMS spacing, engagement level of
sign content, and road geometry) to determine possible limitations on CEVMS
deployment and operation which might reduce distraction to noninterfering levels. This
stage is directed at developing empirical data to support the development of possible
restrictions or regulation of CEVMS to reduce potential driving hazards.
• Stage 3—As related to CEVMS, researchers would have to investigate the relationship
between distraction, defined in terms of eye glance behavior and safety surrogate
measures (driving conflicts, errors, etc.), and safety, defined more directly in terms of
crashes, fatalities, injuries, and property damage. This stage focuses on validating the eye
glance and safety surrogate measures used to infer attention and distraction effects of
CEVMS through the primary safety criterion of protecting life, health, and property.
The above stages of the proposed research program are to be pursued sequentially. The initial
stage is directed at determining whether or not a potentially harmful CEVMS distraction effect
exists. To demonstrate such a distraction effect, an independent and objective threshold criterion
of excessive distraction must be employed. If no potentially harmful distraction is shown, at least
as far as driving safety is concerned, there would be little need to pursue the second stage of
developing a basis for regulating CEVMS or the third stage of relating CEVMS distraction to
more direct measures of safety (crashes). If potentially harmful distraction is shown in the first
stage, the second and third stages would be implemented in order. The order of the last two
stages may appear to be reversed. Normally, it would seem desirable to establish a relationship
29