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tested in this research generally served their intended pur- pedestrians who are blind that they are leaving the pedestrian
pose; however, the selected type of material evaluated proved way and entering the vehicular way. Also, planting strips along
to be too quiet given the high ambient noise at the test site. the sidewalk serve as a barrier that discourages pedestrian
The biggest problems with the treatment arose when vehicles access to the roadway at places other than the crosswalk and
were traveling very slowly and the audible cues from the sound make it less likely that a blind pedestrian will inadvertently step
strips were not noticeable. from the paved walkway into the paved roadway at any point
The use of a pedestrian signal at the CTL is a possible treat- other than the crosswalk or begin crossing from the wrong
ment that can be tied in with the existing signal control at the point without realizing the intersection is a roundabout. They
main intersection. There are some challenges to tying the CTL also provide a trailing surface that long cane users can use to
signal into the existing controller, especially when an intersec- locate the crosswalk.
tion has multiple CTLs that are to be signalized. But an exist- The splitter island should be wide enough for pedestrian
ing signal phasing strategy is to use vehicle overlap phasing refuge and to enable a two-stage crossing. Note that splitter
with a pedestrian signal across the crosswalk. If adding the CTL islands that are not raised islands but are simply painted on
signal to an intersection with a long cycle, the expected pedes- the pavement are not detectable to blind pedestrians.
trian delay may be high and needs to be assessed in the context Several blind pedestrians commented that landscaping
of the total pedestrian crossing. At a busy intersection such and trees on the splitter island (at the two-lane roundabout)
as the test site, a diagonal pedestrian crossing (e.g., from the blocked some of the sound from the lane behind them when
southeast to northwest corner) would entail the use of four sig- they were crossing from the island to the curb. This helped
nalized crossings (CTL, main road, side road, CTL). Signalized with sound separation and discrimination of the traffic com-
CTLs have been observed in several cities across the United ing toward them from the traffic going away from them, and
States and are rather common in other countries. may therefore be beneficial for single-lane roundabouts as
In addition to a standard pedestrian-actuated signal, a well. Landscaping on the splitter islands should not block the
PHB may be another alternative for CTLs. The advantages of view of the crosswalk for drivers.
the allowable vehicle movements during the "Flashing Red"
phase are reduced with shorter crossings and associated shorter
Two-Lane Roundabouts
"Flashing Don't Walk" phases. However, some vehicle delay
savings are expected to remain. The allowable provision in The two-lane roundabout design should promote low speeds
the MUTCD to let the pedestrian display at the PHB rest in a at the crosswalk through geometric design, where possible, or
dark mode may be considered for CTLs since many (sighted) through supplemental traffic-calming treatments (bulb-outs
pedestrians may not require the added assistance provided by or raised crosswalks). The raised crosswalk design showed
the signal. potential at the tested location and resulted in significantly
reduced pedestrian delay and interventions; however, there is
concern related to observed multiple threat conflicts, and more
Single-Lane Roundabouts
research is need to clarify risk. The impact on traffic operations
The design of single-lane roundabouts should encourage is believed to be directly related to the design of the raised cross-
low vehicle speeds in the vicinity of the crosswalk. Low speeds walk (vertical elevation and transition slope). In the tested
are shown to correlate with increased yielding behavior and installations, vehicle impacts were reasonable. More testing is
reduced injury in case of a collision. There is some concern that necessary to ensure that this treatment has broader applica-
lower speeds (and associated lower vehicle noise) may reduce tion to other geometries and traffic patterns.
the ability of a blind pedestrian to detect crossing opportunities The use of a PHB showed promise at the tested location in
(yields), which is a question that deserves the attention of terms of reducing pedestrian delay and interventions, but was
researchers. associated with some misunderstanding and/or noncompli-
The design of a single-lane roundabout should encourage ance on the side of drivers and blind study participants. A
narrow (or standard) lane widths in the vicinity of the cross- simulation-based sensitivity analysis showed that the use of the
walk. Lanes that flare out too early unnecessarily increase the PHB phasing, a two-stage crossing, and an offset exit portion
crossing distance for pedestrians and further may allow vehi- of the crosswalk all result in improvements to vehicular oper-
cle passing in the vicinity of the crosswalk, thereby creating a ation compared to a standard one-stage pedestrian-actuated
potential multiple-threat situation. This was observed at one signal. If signalization is considered at a two-lane roundabout,
of the three tested single-lane roundabouts and resulted in these alternate signalization strategies should be considered.
some near-interventions. Detectable warnings complying with the draft PROWAG
Detectable warnings complying with the draft PROWAG are required at both curb and island ends of crosswalks to warn
are required at both curb and island ends of crosswalks to warn pedestrians who are blind that they are leaving the pedestrian
