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shows the questionnaires used during the debriefing process ity fields, the research team represented a diverse and qualified
for different sites. group for this task. Therefore, an independent internal team
survey was conducted to weigh different treatment options in
terms of their perceived effectiveness, cost, and applicability
Identification and Selection
to the different facility types.
of Treatments
This section describes the process used by the research Internal Team Survey
team to collectively arrive at a set of treatments to be experi-
mentally applied at selected single- and two-lane roundabouts The internal team survey was intended to reduce the long
and CTLs. The objective of the treatments was to improve list of treatments to a short list to move forward in the field-
access for blind pedestrians. The definition for what consti- testing stage of the project. A survey tool was developed to
tutes an accessible crossing and the performance evaluation gather the input of all members of the research team. The
framework used in the analysis is presented in Chapter 4. The survey tool and team results are provided as Appendix C.
treatment selection process combined information on treat- Each member of the research team evaluated each of the
ment effectiveness available in the literature and the applied potential treatments in terms of (1) the extent to which each
research and practical experience of those on the project team. of the treatments would have an impact on the likelihood
Given the operational similarities of roundabouts and CTLs of gap detection (estimated separately for blind and sighted
discussed in Chapter 1, comparable treatment strategies were pedestrians), (2) the likelihood of having an impact on yield
hypothesized to enhance accessibility at both facility types. detection, and (3) the likelihood of drivers yielding to pedes-
Accessibility for blind pedestrians at these types of facilities trians. These are referred to in the survey as behavioral attri-
butes associated with treatments. Estimates were also provided
is a function of (1) traffic conditions associated with a low
for the extent to which each potential treatment was believed
occurrence of naturally occurring crossable gaps, (2) blind
to have an impact on performance (i.e., both the delay and risk
pedestrians' ability to detect the presence of naturally occur-
experienced by blind and sighted pedestrians), as well the
ring gaps, (3) the likelihood of motorists yielding to pedes-
effect on vehicular traffic. Estimates were also provided for the
trians, and (4) the ability of blind pedestrians to reliably
perceived applicability of treatments for implementation at
detect those yield events. Given the dynamic nature of the
single- and two-lane roundabouts and at CTLs.
pedestrianvehicle interaction, the temporal efficiency is
Treatments were divided into six categories following the
another critical aspect since gap duration and driver patience
discussion in Chapter 2: driver information treatments, traf-
(in yielding) are limited.
fic calming treatments, pedestrian information treatments,
In addition to the above conditions for crossing, equivalent crosswalk geometry modification, signalization with APS,
access to these types of facilities by blind and sighted pedestri- and grade separation.
ans will also be a function of how effectively the blind pedes- The survey results suggested that most driver informa-
trian can (1) locate the crosswalk, (2) correctly align for cross- tion treatments and traffic calming treatments were judged
ing, and (3) maintain alignment while crossing. Failures of to have no substantial impact on blind pedestrians' ability to
facilities to support these requirements can result in (a) an detect gaps and/or yielding vehicles. However, these treat-
increase in the total pedestrian travel time associated with ments were generally believed to be beneficial to sighted pedes-
crossing, (b) exposure to risk by crossing at an inappropriate trians and were believed to be applicable to single-lane round-
(i.e., unmarked) crossing location, or (c) both an increase in about and CTL crossings, but to a lesser extent to two-lane
crossing time and exposure to risk associated with veering roundabouts. While they weren't believed to affect detection
during the crossing. While the focus of the experimental tri- of crossing opportunities, their perceived impact on increasing
als in this research was on the actual crossing task, these other frequency of crossing opportunities (more yields) was deemed
aspects are discussed in general terms. beneficial. At a relatively low cost and perceived low impact to
The long list of treatments given in Chapter 2 represents vehicular operations, one treatment in each of these categories
all treatments that were deemed to have some potential in was considered for further testing: a pedestrian-actuated flash-
improving the accessibility of roundabouts and CTLs. It was ing beacon and a raised crosswalk.
beyond the scope of this project to test all of these treatments For pedestrian information treatments, members of the
at multiple facility types. Consequently, a process had to be research team hypothesized mixed effects on gap and yield
devised to arrive at a short list of treatments to propose for detection, although generally higher effectiveness than treat-
further testing. Having completed the literature review on ments in the previous category. Estimated effectiveness for
treatment types and effectiveness and having extensive prior blind pedestrians was moderate for surface treatments intended
research and field knowledge in the engineering and accessibil- to generate additional acoustic cues and higher for more
