Figure 1. Chief Okemos Roundabout (Okemos, Michigan)
Photo courtesy of Dave Sonnenberg, Director of Traffic and Safety, 
Ingham County, Michigan Road Commission

Background
Modern Roundabouts
Crossing at Traditional Intersections
Crossing at Roundabouts
Improvements Worth Investigating
Public Rights-of-Way Access Advisory Committee Recommendations

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BACKGROUND  Roundabouts are replacing traditional intersections in many parts of the U.S. This trend has led to concerns about the usability of these free-flowing intersections by pedestrians who are blind and visually impaired.

Most pedestrians who cross streets at roundabouts use their vision to identify a ‘crossable’ gap between vehicles. While crossing, they visually monitor the movements of approaching traffic and take evasive action when necessary.

Blind pedestrians rely primarily on auditory information to make judgments about when it is appropriate to begin crossing a street.  The usefulness of such non-visual information for crossing streets at roundabouts is under study, but many issues remain.  

Recent research sponsored by the Access Board, the National Eye Institute, and the American Council of the Blind suggests that even single lane roundabouts in residential areas can sometimes present significant usability challenges (and therefore risks) to the pedestrian who has a vision impairment.  Providing blind pedestrians the same information that sighted pedestrians obtain visually to select gaps for crossing at a roundabout is key to successful solutions.

This bulletin:

MODERN ROUNDABOUTS

There are an estimated 40,000 modern roundabouts worldwide, and more than 200 have been constructed in the United States. Most of these have been built within the last 5 years. Many jurisdictions are now considering roundabouts to improve vehicle safety, increase roadway capacity and efficiency, reduce vehicular delay and concomitant emissions, provide traffic-calming effects, and mark community gateways.

Figure 2. Typical urban double-lane roundabout
from Roundabouts: An Informational Guide (FHWA)

Roundabout design in the U.S. has not yet been standardized, although several types have been defined in industry publications. Engineers use a variety of design techniques, mostly geometric, to slow vehicles as they approach, circulate, and exit a roundabout. Differing design practices in Europe and in Australia continue to influence U.S. engineers as they refine design approaches for application in urban, suburban, and rural areas.

Studies conducted in western Europe -- where roundabouts are common -- and in the U.S. have generally found that crashes at roundabouts are less severe than vehicular crashes at more traditional intersections.  

The reduction in serious vehicular crashes is the most compelling reason cited by transportation engineers for the installation of roundabouts. Roundabouts increase vehicular safety for two main reasons: 1) they reduce or eliminate the risk arising at signalized intersections when motorists misjudge gaps in oncoming traffic and turn across the path of an approaching vehicle; and 2) they eliminate the often-serious crashes that occur when vehicles are hit broadside by vehicles on the opposing street that have run a red light or stop/yield sign.

The research findings on pedestrian safety at roundabouts are less clear. There have been relatively few studies, mostly conducted in Europe, concerning pedestrians and roundabouts. Pedestrian-vehicle crashes, the most commonly used dependent measure in pedestrian safety studies, tend to occur infrequently both before and after an intersection is converted to a roundabout. As a result, it is difficult to draw firm conclusions from the literature regarding pedestrian safety and use of roundabouts.

One issue that is often not considered in pedestrian research is the degree to which pedestrian volume may change when intersections with signal or stop-sign control are converted to roundabouts. There is a need for research on this topic as well as a broad range of other pedestrian-related concerns at roundabouts.

Little is known about the use of roundabouts by older pedestrians, children, and pedestrians with cognitive disabilities.

The differences between modern roundabouts and traditional intersections controlled by traffic signals and stop signs have important implications for pedestrians who are blind.  While some of these implications are not yet well understood, they must be considered by any transportation engineer or planner whose goal is to create an accessible pedestrian environment.

CROSSING AT TRADITIONAL INTERSECTIONS

The techniques and cues used by blind pedestrians crossing at traditional intersections are diverse and vary by location and individual. Many blind pedestrians have received instruction in using these techniques from orientation and mobility (O&M) professionals. In the most common technique for crossing at fixed-time signalized intersections, pedestrians who are blind use traffic sounds to align themselves properly for crossing and then begin to cross when there is a surge of through traffic next to and parallel to them. This occurs at the onset of the walk interval, when the traffic signal changes in the pedestrian’s favor. Cues that can be used for identifying that a street is just ahead, and for determining when to cross, include traffic sounds, the orientation and slope of curb ramps, textural differences between the street and sidewalk, detectable warnings underfoot, locator tones at pedestrian pushbuttons, and audible or vibrotactile information from accessible pedestrian signals (APS).

Key street-crossing tasks for the blind pedestrian include:

When traffic sound cues are absent (e.g., when there are no cars on the street parallel to the pedestrian’s line of travel, and thus no auditory cue that the signal has changed) or unpredictable (e.g., when the intersection is of a major and minor street, and traffic signals are actuated by vehicles), information may be insufficient for determining the onset of the walk interval. In such situations, APS systems may be necessary. New guidance on the use of APS appears in the 2000 edition of the Manual of Uniform Traffic Control Devices (MUTCD);  a new (2003) synthesis of current APS technologies developed as a product of NCHRP 3-62 research is posted to the Pedestrian-Bicycling Information Center website at  www.walkinginfo.org/aps/

CROSSING AT ROUNDABOUTS

Orientation and mobility techniques used by blind individuals at traditional intersections rely heavily on traffic sounds. When traffic signals and stop signs regulate traffic movements at intersections, the resulting breaks in traffic flow provide identifiable and predictable periods – gaps – during which pedestrians can cross. Such predictable breaks do not usually occur at roundabouts, and so pedestrians must make judgments about the speed and travel paths of approaching vehicles (and the duration of gaps between vehicles).

It appears that sighted adults are generally able to safely make such judgments, although some pedestrians (e.g., those with cognitive impairments, children -- see Figure 3) may have difficulty doing so. Research suggests that the selection of appropriate gaps at roundabouts is problematic for blind pedestrians at some roundabouts. 
 

Figure 3  Pedestrian with cognitive disability crossing in roadway

Traffic sounds at roundabouts can provide ambiguous cues.  Circulating vehicles can mask the sounds of entering and exiting traffic, making it difficult to identify an appropriate time to cross. At exit legs, auditory information may not be adequate to reliably convey whether circulating vehicles will exit or continue around the roadway.

		At entry legs, it may not be clear from auditory information whether a driver intends to yield to a waiting pedestrian. While research has shown that driver- yielding rates increase at low speeds, many drivers do not yield to blind pedestrians at crosswalks (see Figure 4) and yielding behavior may be difficult to detect.
Figure 4. Driver fails to yield to pedestrian using long cane
The curvilinear layout of roundabouts poses several challenges to blind pedestrians. One challenge is obtaining information about the location and direction of the crosswalk. Sidewalks at roundabouts often curve in large arcs and, unlike traditional intersections, rarely lead directly to crosswalks. Instead, crosswalks are typically to the pedestrian’s side (see Figure 5) and must be located using different strategies and sources of information than those used at traditional intersections.
	Figure 5. Planter used to indicate crosswalk location
	Another challenge is aligning the body with the crosswalk prior to crossing (see Figure 6). At traditional intersections, a common nonvisual technique for accomplishing this is to use traffic sounds to line up to face parallel to the traffic to one’s side (i.e., one’s ‘parallel street’ traffic). This technique is probably not useful at roundabouts.
Figure 6. Crosswalk not aligned with approach

At some roundabouts, however, some of the nonvisual street-crossing methods used at traditional intersections may be appropriate. For example, it would appear to be appropriate to cross during the periods of ‘all quiet’ that occur at roundabouts where the traffic volume is very light (e.g., 1 lane roundabouts in residential areas) or where there are long periods during which there is no traffic (e.g., due to traffic signals at nearby intersections). However, as vehicles become quieter, this technique may be unsuitable at both traditional and roundabout intersections.