|
|
|
|
|
ROUNDABOUT
Excerps
from "ROUNDABOUTS: An Informational
Guide"
Published by the Federal
Highway Commission
and
Roundabout access for the blind
and
ACCESS ADVISORY
COMMITTEE RECOMMENDATIONS
Regarding - Roundabouts: An Informational Guide According to the Federal Highway Administration the safest roundabouts have their entrances at equal angles apart. “As the angle between entries decreases, the frequency of crashes increases. For example, an approach with an angle of 60 degrees to the next leg of the roundabout increases crash frequency by approximately 35 percent over approaches at 90-degree angles.” (FHWA-RD-00-067 4.2) Therefore, the FHWA recommends to “maximize angles between entries” in order to improve safety. The closer the entries come to one another, the more possibility there is of collisions. The merging entrances to the proposed roundabout of US9 and NY 9H are a good example of how not to build a roundabout. Roundabouts: An Informational Guide published in 2000 by the Federal Highway Administration (FHWA) - acknowledges the need for improvements in roundabout access for blind pedestrians. "It is expected that a visually impaired pedestrian with good travel skills must be able to arrive at an unfamiliar intersection and cross it with pre-existing skills and without special, intersection-specific training. Roundabouts pose problems at several points in the street crossing experience, from the perspective of information access." "Unless these issues are addressed by design, the intersection is ‘inaccessible’ and may not be permissible under the ADA …[M]ore research is required to develop the information jurisdictions needed to determine where roundabouts may be appropriate and what design features may be appropriate for the disabled, such as audible signalized crossings." Title II of the Americans with Disabilities Act (ADA) requires that new and altered facilities constructed by, on behalf of, or for the use of state and local government entities be designed to be readily accessible to and usable by people with disabilities (28 CFR 35.151).
Across the U.S., roundabouts are being designed and installed at a rapid pace. It is becoming increasingly clear that current roundabout design practices do not yield the same access to crossing information for blind and low vision pedestrians as for sighted pedestrians. An accessible roundabout will provide nonvisual information about crosswalk and splitter island location, crossing direction, and safe crossing opportunities. An understanding of the auditory, tactile, and other cues used by blind individuals as they negotiate intersections will aid engineers and planners in designing and building accessible roundabouts. Orientation and mobility (O&M) specialists can aid transportation professionals in understanding the demands of non-visual travel and the strategies that blind people use to successfully meet these demands. Much research and development work is needed to improve the usability of modern roundabouts by persons with blindness and visual impairments. It is essential that transportation engineers and planners involve themselves in this R&D by working to devise, implement and test design features with potential for improving accessibility. Promising avenues for further investigation fall into four broad task categories: 1. LOCATING THE CROSSWALK AND ESTABLISHING ALIGNMENT Landscaping, planters, pedestrian channelization, bollard-and-chain separation, railings, and other architectural features can delineate paths that lead to the crosswalk and prevent or discourage crossing at locations other than the crosswalk (see Figure 4 above). A distinctive edge, particularly paving-to-grass or a raised curb can provide orientation to the crossing direction. High-contrast markings and pedestrian routes that are well-lit at night will be useful to pedestrians who use residual vision to travel, the larger proportion of pedestrians who have vision impairments. Lighting will also enhance pedestrian visibility to drivers.
When alignment using traffic sounds is not possible, other sources of alignment information must be available. Curb ramps with returned edges aligned with crosswalk direction offer useful cues for establishing a line of travel. It is probably also the case that when curb ramp slope is sufficiently steep to be detected underfoot, additional information for alignment can be provided by aligning the slope of the ramp with the crosswalk. However, the usefulness of slope information for alignment is an unresolved research question, and it raises issues where non-standard crosswalk location (e.g., diagonal or apex ramps) may give misleading information that can result in crossings outside the legal or marked crosswalk. 2. DETECTING WHEN IT IS APPROPRIATE TO CROSS Designing roundabouts that provide pedestrians with nonvisual information about the appropriate time to initiate a street crossing appears to be the greatest challenge facing transportation engineers at roundabouts. Key issues include:
It is more difficult – and dangerous – to cross in front of stopped vehicles if the pedestrian is crossing more than one lane. Vehicles in the lane nearest the pedestrian stop but vehicles in other lanes (moving in the same direction) may not. To facilitate crossing in front of stopped vehicles, consideration should be given to locating crosswalks before the point where two-lane roads are flared to accommodate multiple-lane entries and exits. Research is currently underway to determine the likelihood that vehicles will yield to pedestrians traveling with dog guides and long canes. Preliminary results about driver yielding behavior collected at 3 crosswalks suggest that most drivers do not yield to blind pedestrians waiting at a crosswalk. This is particularly a problem at exit lanes. When vehicles do stop, they are sometimes not detected. This is typically the case when vehicles stop several car lengths away from the pedestrian, when the vehicle is relatively quiet (e.g., hybrid gas/electric vehicles), and/or when the sounds of other vehicles mask the sounds of the yielding vehicle. However, the strategy of crossing in front of a stopped vehicle should work where some vehicles stop and are detectable. Some designers have incorporated stop bars and LED in-roadway warning lights (MUTCD, Chapter 4L) to encourage vehicles to yield to pedestrians at crosswalks. The use of 'YIELD TO PEDESTRIAN' signage at yield lines may also be effective. Recommendations from a roundabouts summit sponsored by ITE and FHWA in December 2002 included raised crossings, particularly on exit legs to discourage driver acceleration. Testing of the effectiveness of 'rumble strips' or similar sound-generating pavings before entry and exit has also been proposed. Research is needed to determine if pedestrians can gain useful information on approaching and yielding vehicles from such cues. Jurisdictions are also experimenting with ‘smart’ intersections that can sense and signal pedestrian presence. In situations where there are few 'crossable' gaps and where vehicles do not stop for pedestrians waiting to cross (or, because of multiple lanes, it is unsafe to cross in front of a stopped vehicle), specially-designed pedestrian signals -- models include 'HAWK' and 'TOUCAN' schemes that blink in amber unless activated. Pre-emption signals utilized for emergency vehicles and trains may also have some application to provide street-crossing opportunities for pedestrians who are blind. Research is needed to determine how to optimize such signalization for both pedestrians and drivers. Continuing advocacy for signalization can be expected until effective alternatives are developed. Roundabouts with multiple lane entrances and exits, where signalization is more necessary to provide crossable (and detectable) gaps for pedestrians, would experience greater delays from signalization. 3. REMAINING IN THE CROSSWALK Several design approaches may be used to provide directional information in the crossing. Jurisdictions have experimented with ultra-high contrast markings and crosswalk lighting (useful for pedestrians who have low vision); raised crosswalks to provide a boundary, and providing a raised guidestrip at the centerline of the crosswalk. By using the constant-contact cane technique, a blind pedestrian can identify and use tactile surface cues that provide information about the direction of the crosswalk. 4. DETECTING THE DESTINATION SIDEWALK OR SPLITTER ISLAND Detectable warnings at splitter islands and destination curb ramps signal one’s arrival at a pedestrian refuge. Splitter islands should be demarcated with detectable warnings at each street/sidewalk edge, separated by a width of untextured sidewalk surface. Because detectable warnings mark the beginning and/or end of a safe pedestrian area, they should be applied in pairs, separated by standard sidewalk surfacing. Research indicates that 24 inches of detectable warning surface is needed for underfoot detection while walking. The use of similar design features across roundabouts will enhance their accessibility to persons who are blind. Consistency in the location of crosswalks, in the design of splitter islands, in the use of bollards and pedestrian channelizing devices, separators, and edging, and in the use of landscaping features can provide effective non-visual cues for negotiating roundabouts. When a roundabout is introduced to a community through newspaper and TV stories, be sure to emphasize that pedestrians are expected to cross there. Show photos and film of drivers yielding to pedestrians.
Empirical research about the accessibility of modern roundabouts is in its infancy. In 1999, a program of research on roundabout accessibility was initiated by Western Michigan University and Vanderbilt University. Conducted at three modern roundabouts in metropolitan Baltimore, Maryland, the study provides information about the ability to use vision and hearing to distinguish ‘crossable’ gaps in traffic from gaps that are too short to afford safe crossing. ‘Crossable gaps’ were defined as those that would have allowed pedestrians sufficient time to cross from a curb to a splitter island before the arrival of the next vehicle at the crosswalk. The results of the study suggest that there are significant differences in the ability of blind and sighted pedestrians to determine whether it is safe to initiate a crossing at some roundabouts, presumably because of differences in the way information is obtained to make decisions about crossings. The Western Michigan/Vanderbilt team also conducted a comparable study at three roundabouts in the greater Tampa, Florida area with similar results. A principal finding of this research was that the ability to judge whether gaps are crossable or not is strongly affected by vehicle volume. For example, the judgements of blind and sighted pedestrians were similar at a single-lane roundabout at mid-day, but blind pedestrians were significantly disadvantaged at rush hour. The team is currently studying the behavior of blind and sighted pedestrians as they cross at roundabouts and the behavior of drivers as they approach blind pedestrians waiting at uncontrolled crosswalks (both at roundabouts and mid-block crosswalks). Preliminary analysis suggests that few drivers yield, although this varies widely from crosswalk to crosswalk. While such research has begun to address several of the key issues cited earlier in this bulletin, it is clear that much more work remains to be done.
The dearth of research addressing the negotiation of roundabouts by blind pedestrians has prompted Federal funding of several projects on this topic. The first, funded by the National Eye Institute of the National Institutes of Health, was awarded in 2000 to a consortium led by Western Michigan University. This project emphasizes the identification of variables affecting blind pedestrians’ safety while crossing streets at roundabouts and treatments to enhance this safety. The second project, funded by the National Institute on Disability and Rehabilitation Research, was awarded in 2001 to a consortium led by the Sendero Group, LLC. This project emphasizes the identification of wayfinding information needed by blind pedestrians at roundabouts (e.g., crosswalk location, intersection geometry) and ways to convey this information to the pedestrian. A third project, focused specifically on the usability of roundabouts and slip lanes by pedestrians who have vision impairments, will be awarded in 2004 by the National Cooperative Highway Research Program (a prior NCHRP study still underway will identify "geometric, traffic, and other characteristics that are expected to affect the safety and operation of all roundabout users, including bicycles, pedestrians, and pedestrians with disabilities" and to "refine geometric and traffic control design criteria used for roundabouts, including….treatments for bicycles and pedestrians (including pedestrians with disabilities and including the impact of accessible pedestrian signals on pedestrian access and vehicle operations)…"). The Turner-Fairbanks Research Center of the Federal Highway Administration/DOT has a human factors study newly underway that will test several potential improvements to roundabout usability by pedestrians who have vision impairments. Collectively, these and other projects should significantly enhance engineers’ and planners’ access to information about how to build roundabouts that can be negotiated safely and efficiently by blind pedestrians. ACCESS ADVISORY COMMITTEE RECOMMENDATIONS The U.S. Access Board is an independent Federal agency that develops accessibility guidelines for buildings, facilities, transportation vehicles, and communications technologies and electronic devices covered by the ADA and other laws. In 1999, the Board established a Public Rights-of-Way Access Advisory Committee (PROWAAC) to make recommendations on accessibility guidelines for public rights-of-way. The 33 members of PROWAAC represented Federal agencies, traffic engineering organizations, State and local government transportation and public works agencies, traffic consultants, standard-setting organizations, disability organizations, and others. On January 10, 2001, the PROWAAC submitted its report to the Board recommending a new national set of guidelines for accessible sidewalks, street crossings, and related pedestrian facilities. The report includes several recommendations regarding access to roundabouts. In particular, the report recommends:
The Access Board is considering Committee recommendations as it adapts current ADA standards for more effective use in the public right-of-way. A draft guideline proposing pedestrian signals at all roundabout crossings was published in June 2002. The Board is currently analyzing comment to this preliminary proposal and will next develop a Notice of Proposed Rulemaking (NPRM) on guidelines for public rights-of-way for publication in the Federal Register. The NPRM will seek additional public input and comment on the proposed guidelines before a rule is finalized. Further information on the status of this rulemaking is provided on this website. Public comments to the draft are also available online. A summary of the Board-sponsored research is posted to the Board's website. Additional resources on public rights-of-way accessibility available from the Board include:
Resources available from the Federal Highway Administration include:
|
