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ROUNDABOUT ACCESSIBILITY SUMMIT

DRAFT PROCEEDINGS
VERSION 2.0

OCTOBER 28-29, 2002
Location:
Institute of Transportation Engineers Headquarters
Washington, DC
Annotated with Attendee Comments

Introduction

A roundabout accessibility summit took place at the offices of the Institute of Transportation Engineers on Monday, October 28 and Tuesday, October 29, 2002. The final agenda for this meeting is included as Attachment No. 1 to these proceedings. The roundabout section of the U.S. Access Board Draft Public Rights of Way Accessibility Guidelines is included as Attachment No. 2. A roster of the Summit attendees is included as Attachment No. 3. The individual presentations and reports that were discussed at this Summit will become part of the final proceedings and will be labeled as Attachments. These briefing materials, including the Proceedings, will be available in both hard copy and electronic format.

Meeting GOAL and Objectives

The overall goal of this Roundabout Summit was to bring all of the stakeholders together to initiate the dialogue on accessibility issues within roundabouts.

The following meeting objectives were set forth in the September 5, 2002 invitation letter to meeting attendees.

1. To identify existing and innovative solutions, tools, and technologies.
2. To develop information toolkit/package for practitioners.
3. To develop recommendations for industry research.

At the beginning the participants decided to revise the meeting agenda to focus primarily on the goal that was set forth. It was felt that we had to establish a rapport among all of the stakeholders and try to gain an understanding of the viewpoints and positions of each entity.

This meeting represented the first time that regulators, consumers, engineers, policymakers, researchers, and orientation and mobility specialists were gathered in the same room to discuss both individual and mutual needs to provide vehicular, pedestrian access generally, and pedestrian access for blind and visually impaired individuals for roundabouts. All of the stakeholders gained an appreciation for each other's concerns and needs.

What we did accomplish was the following:

1. Technical briefings from regulators, orientation and mobility specialists, traffic engineers, and international roundabout experience;
   
   
2. The identification of issues to be placed "on the table" for future discussion;
   
   
3. The development of a list of future needs and research priorities; and
   
   
4. A willingness of the group to meet again, to continue the dialogue.

Meeting Conclusions and Next Steps

1. We have developed greater awareness and understanding of orientation and mobility techniques used by pedestrians who have vision impairments and of the characteristics of roundabout design that confound analysis by means of these techniques.
   
   
2. There was an acknowledgement of the technical issues that need to be considered to achieve roundabout usability by pedestrians who have vision impairments.
   
   
3. There is an overall need to improve transportation facility access and usability for pedestrians generally.

DONNA SAURERBERGER ALTERNATE STATEMENT: There was an acknowledgement of the technical issues that need to be considered when designing roundabouts to meet the needs of non-sighted pedestrians crossing the roundabout.

4. We need to unite and share ideas on how to make roundabouts serve all roadway users.
   
   
5. The group will meet again to continue the dialogue. We have made considerable progress toward a full understanding of the relevant issues. The next step will be to attempt to develop and test solutions, tools, and prototypical designs in US roundabouts.
   
   
6. We have made a commitment to develop project statements and fund research on the following topics: driver yielding behavior; gap creation, identification and acceptance; detectable surfaces to provide location and wayfinding information; and ITS technologies with respect to roundabout design and operation for pedestrians who have vision impairments.
   
   
7. Existing data on the safety of roundabouts considers only vehicle use.

POST-MEETING ALTERNATE STATEMENT BY RON HUGHES:

There is a need for comprehensive performance data for operational pedestrian crossing behavior at roundabouts.

POST-MEETING ADDITIONS BY RON HUGHES:

8. There is a need to develop analytic tools (models, simulations, etc.) capable of addressing pedestrian performance at the same level as traffic (vehicular) performance.
   
   
9. There is a need to address the advisability of adopting alternative upstream or downstream crossing locations for pedestrian (similar to the UK model). There is no inherent reason why pedestrian crossings must be limited to the immediate area of the splitter island.
   
   
10. Signalization, where used to create a crossable gap for a pedestrian (blind or otherwise, needs to be considered in the context of the entire roundabout, and needs to be considered in light of the performance of the roundabout over time, not just for the duration of the crossing, per se.
    
    
11. The problems experienced by blind pedestrians at roundabouts need to be considered in the broader context of current traffic control concepts governing how to safely and effectively permit pedestrians to cross the path of motorized traffic.

Significant Overarching Comments and Questions

1. There is the perception that a signal guarantees roundabout access to the blind community. [ORIGINAL STATEMENT].

POST-MEETING COMMENT BY RON HUGHES:

Such a statement can be made only given ones definition of what is meant by a 'signal.' Signal concepts differ in terms of how reliably they are able to produce the desired driver behavior (i.e., yield, reduce speed, stop, etc.)

ALTERNATE PROPOSED STATEMENT BY LOIS THIEBALT:

There is the perception that a signal can act to provide and identify a gap.

2. Crash statistics do not address facility usability. The Access Board's goal and mission is to ensure access to facilities for people with disabilities.
   
   
3. Attendees discussed the concept of having a prescriptive set of standards and designs versus the requirement to meet performance standards.
   
   
4. There is the concern that signalization can only act to reduce the operational efficiency of the roundabout.
   
   
5. Signalizing a roundabout adds cost that may make the roundabout design non-competitive with other alternatives. The challenge is to maintain the operational efficiency of roundabouts for all users at a reasonable cost.
   
   
6. Although pedestrians have the right of way and drivers must yield at crossings, sighted pedestrians are in fact expected to defer to vehicles and wait until they have a sufficient gap. The sound of the continuous flow of traffic in the roundabout and on the roundabout approaches masks the audible cues used in orientation and wayfinding so that gap identification cannot be accurate at all locations at all times.
   
   
7. Vehicle fleet changes are occurring; quieter vehicles gaining market share. We need to build that reality into the [roadway] design and operation and into orientation and mobility training.

POST-MEETING COMMENT BY RON HUGHES:

While some sort of 'rumble' strip might serve to alert a blind individual of a vehicle's approach, they cannot be expected to ensure that gap detection by the blind pedestrian will not still be prone to error.

8. Under various levels of control, there is a point where you lose all the benefits of a roundabout.

POST-MEETING COMMENT BY LOIS THIEBALT:

Disagreement with above statement: not so, many are signalized to both safety and capacity benefit. This statement assumes that only vehicles should benefit. You cannot solve a problem by eliminating key variables.

POST-MEETING COMMENT BY RON HUGHES:

Benefits need to be expressed in terms other than the avoidance of vehicle delay and reduction of vehicle crashes.

9. Physical (landscape, buffers, edges and boundaries and detectable surfaces can provide wayfinding and orientation cues. The word "barrier" has particular meaning for the engineering community and should not be used in this context. . Guidance is needed on how to provide information.

POST-MEETING COMMENT BY RON HUGHES:

This is problematic not only for blind pedestrians. Observation of pedestrian behavior at the roundabout used for the NIH modeling work revealed that pedestrian crossing location, even for sighted pedestrians, is not well controlled.

10. What is the appropriate amount of control required? Should consideration be given to the whole range of control types, including full traffic signals, yield, flashing signal operations, and stop signs? If signals are to be used, where should they be located?

POST-MEETING COMMENT BY RON HUGHES:

Need to differentiate 'minimum control required' in terms of the facility cost of the control versus minimum control from the standpoint of that which is required to achieve a stated level of driver (stop, yield, reduce speed, etc.) and pedestrian (gap detection/selection, etc.) behavior.

11. Would the development of a typology of roundabouts meet the intent and requirements of the Access Board's objectives? The proposal that was placed 'on the table' would require a specific level and type of traffic control for a specific set of roundabout characteristics. There was a spirited discussion on this proposal. Specific comments relating to the roundabout typology proposal includes:
    
    
    1. What variables or breakpoints are relevant for all users?

POST-MEETING COMMENT BY RON HUGHES:

To define 'breakpoints' one needs to know with some certainty the functional relationships between key variables. We don't have that information yet.

2. We cannot use land use as one of the characteristics since land use is subject to change (e.g., rural areas becoming suburbanized). Instead, typologies could be developed based on geometric design, speed, AADT, etc.
   
   
3. The same roundabout will function differently at different times of day. Every roundabout might need signal control at some point.
   
   
4. We need more information and research on the following variables and the relationship of each of the variables to each other with respect to gap detectability and the possible development of typologies to establish how to provide usability to pedestrians who are blind at a roundabout: (1) vehicular volume; (2) vehicle speed (reaction time); (3) single vs. multiple lanes within a roundabout roadway; (4) length of crosswalk; (5) location of crosswalk relative to central island; (6) vehicle gap distributions; (7) additional vehicle access in zone; (8) acoustic environment; (9) driver behavior; and (10) entry/exit geometrics and walking speed.

POST-MEETING COMMENT BY RON HUGHES:

(2) Speed (reaction time);

Do you mean reaction time as it relates to vehicle and pedestrian speeds?

(4) Length of crosswalk

and the availability and functional characteristics of 'refuge' islands;

(5) Location of crosswalk relative to central island;

Need to be more specific; do you mean upstream/downstream from the roundabout proper, or with respect to stop bar?

(8) Acoustic environment

As defined both in terms of vehicle sounds as a function of geometry, etc.; as well as the auditory discrimination capabilities/performance of the full range of pedestrians;

(9) Driver behavior

with respect to the likelihood of yielding to specific types of information

5. The development of a roundabout typology may not be the right solution. If pedestrian access is provided, the roundabout must be usable by all. [Note: This was an opinion by one individual; there was not a consensus on the above statement.]

Issues/Problems/Needs/Challenges

Regulatory Issues

1. The Draft Public Rights-of-Way Accessibility Guidelines require pedestrian-activated signals at roundabouts because of concerns about access for individuals who are visually impaired or who have difficulty crossing for other reasons.

2. Modifications to the Draft Public Rights of Way Accessibility Guidelines will be based on comments and information received by the Access Board. Notice of Proposed Rulemaking and a regulatory analysis will be the next step.

3. We need to be able to achieve usability. We can try to gain equivalent facilitation through technical innovation, but consumers have a strong preference for environmental solutions.

4. Attendees noted that the Draft Guidelines have identified specific treatments that shall be used as opposed to a performance standard (e.g., provide whatever is required to make sure that a functional gap is present). However, other attendees also noted that the ADA allows 'equivalent facilitation'. This means that other treatments can be used, as long as they provide access. The designer/engineer will have to defend his choice/decision if an ADA complaint is filed.

POST MEETING COMMENT BY DONNA SAUERBURGER:

5. The Access Board must develop technical standards based on the law. If pedestrian facilities are provided at a roundabout, they must be accessible to and usable by people with disabilities.

[Many possible roundabout locations will not need pedestrian access provisions.] [Peirce added statement]

POST MEETING COMMENT BY LOIS THIBAULT:

Federal funding is immaterial; state and local governments are covered by ada requirements regardless of funding source.

POST-MEETING COMMENT BY RON HUGHES:

So, if the indicated roundabout crossing location for all pedestrians was at a point upstream/downstream from the circulating motorway, and if conditions (e.g., gap frequency and duration) at those locations provided all pedestrians an equal opportunity to cross (equal in terms of delay, in terms of safety, and in terms of 'difficulty'/workload) then the requirement for accessibility had been met?

Engineering Issues

1. The following engineering variables must be addressed in any future requirements to accommodate pedestrians generally, and pedestrians who are blind or have low vision, within a roundabout environment:
   
   
   • Geometric requirements
   • Exits and entrance issues (e.g. speed differential)
   • Design speed (affects the control intervention that is selected)
   • Use and effectiveness of various surface [pavement] treatments
   • Use of staggered crossings
   • Need to understand the role of speed with sight distance
   • Differential requirements of single lane roundabouts versus multi-lane roundabouts.
   • Orientation of crosswalk
   • Landscaped areas
   • Wayfinding. We need to understand the effectiveness, ease of application, durability, and maintenance needs of various wayfinding surface technologies.
   • Engineering characteristics of the human component of the system. [Ron Hughes]

POST MEETING COMMENT BY ERIC WORRELL, P.E., FHWA RESOURCE CENTER, ATLANTA:

Importance of clear sight lines between the driver and pedestrians. No, blind people can't see the drivers, but if the driver can't see the blind person clearly until the last instance, then the risk to the pedestrian, especially the visually disabled is much greater. There is a shortcoming in the roundabout guide. [We need to indicate that] clear sight lines to the top of the ramp rather than just the beginning of the cross-walk [are needed]. My sense was that there was then general agreement on this issue.

Janet Barlow showed a video where a blind pedestrian was waiting with a guide to cross the street near a roundabout. Many cars passed without slowing or stopping for the pedestrians. But in the case of the video there was a substantial stand of vegetation just up stream from the curb cut. Drivers clearly [were] not becoming aware of the presence of the pedestrians until it was too late for a safe controlled stop. I don't know that they would have been anymore courteous if the stand of trees wasn't there - but I do know the pedestrians would have been at less risk.

2. Traffic Control.
   
   Discussion of hierarchy

• Static signs and markings (yield markings, stop signs)

• Crosswalk treatments: markings, raised, textured; transverse markings/rumble strips on the approach lanes;

• Yield control [Need to be more specific, Ron Hughes]

• Warning Devices (static or real time) such as alternating flashing beacons (always there and in pavement lighting/crosswalk lighting, overhead lights, and overhead lighted signs

• Dynamic Message Signs

• Stop Control such as (1) stop signs; (2) flow metering to create gaps (force gaps for pedestrians-no one has ever tried it;

[Operationally, how and at what point, would such gaps in traffic be generated?] [Ron Hughes]

• (3) half signals (signal on one side or the other/ exit vs. entry; and (4) "hawk" signal (activates overhead flashing yellow, steady red, flashing red); and

• Full signal control: (1) by intersection leg; (2) by direction; and (3) for the entire roundabout. [What are the operational impacts on traffic associated with each control concept?] [Ron Hughes]

3. Gaps
   • If information about gaps, or frequency of crossable gaps falls below a minimum threshold, that may indicate the need for a signal.

[This suggests that a signal might be provided if, and only if, it were "impossible" for a {blind} person to cross. What about the notion of equivalency? At what point, either in terms of 'delay' or 'workload'] would conditions fall below threshold?] [Ron Hughes]

• Functional gaps would be defined as gaps that are as frequent, detectable and of a duration, adequate to afford crossing, and that are substantially equivalent opportunity to that afforded to other pedestrians.

Note: Version 1.0 of the minutes used the term "measurable gaps." It has been recommended by a number of attendees that we use the term functional gaps."

[Ron Hughes: All gaps are measurable; so are we talking about those measurable gaps that are crossable?]

• There is a need to understand gap acceptance by different populations (e.g. older pedestrians misjudge gaps).

POST-MEETING COMMENT BY RON HUGHES:

It is important to distinguish between 'gaps' as a measurable phenomenon- that what it is that blind pedestrian is actually using as a basis for the selection of when to cross. Two measurable gaps may be identical, but be functionally different in terms of the pedestrian's ability them as having to identify them as having the same temporal characteristics. For example, the pedestrian may consider gaps of the same measured duration 'different'. This might be based upon when sounds are being emitted by a 'conventional' vehicle or a 'quiet' vehicle.

• Can the existence of a gap be done through the use of an accessible pedestrian signal?

POST-MEETING COMMENT BY RON HUGHES:

By accessible pedestrian signal, I assume you are referring to the system's ability to 'sense' the presence of a safe/crossable gap and the ability to somehow communicate that (auditorially, tactually, etc. to the waiting pedestrian). While possible, it introduces the variable of how effectively that 'information' can be transmitted from the system to the pedestrian, and the pedestrian's response (reaction time) to the signal. The problem is how to define the information required for the system to make the determination (sensor locations, processing required, etc.) that a safe and crossable gap is, in fact, 'present."

Research Needs

1. Models are needed of behavior of motorists and pedestrians in roundabouts. Need to make assumptions about driver yielding behavior and other uncertainties.

POST MEETING COMMENT BY DONNA SAUERBURGER: Needs clarification. Do we mean research is needed to able to predict what drivers will do?

POST-MEETING COMMENT BY RON HUGHES:

There are models currently available (e.g., VisSim) that permit one, at a minimum, to conduct a sensitivity analysis based upon presumed differences in pedestrian crossing characteristics and differences in traffic characteristics. Such models need to be modified to permit users to analyze the effects of pedestrian 'mix' (proportion of pedestrians exhibiting different crossing characteristics) as well as the probabilistic nature of driver yielding performance.

2. Gap acceptability and detectability. We need timely and accurate information about gaps including how to create gaps, how to selectively increase gap length and the number of gaps; how to improve pedestrian detection of gaps and gap length and how to reliably communicate gap information in a timely fashion to blind pedestrians.
   
   
3. Informational surfaces. Investigate markings and colors for drivers (red approaches, squiggly lines).
   
   
4. Intelligent Transportation Systems. Determine the extent to which ITS solutions can be used within the roundabout environment to accomplish both accessibility and traffic movement objectives.

POST-MEETING ADDITION BY RON HUGHES:

5. Investigate the potential effectiveness of potential 'structural' changes to conventional roundabout design from the standpoint of pedestrian crosswalk location, physical measures for traffic calming/speed reduction at or beyond exit locations, etc.
   
   
6. Research should be coordinated and funded between the following organizations: U.S. Access Board, FHWA, ITE, TRB, and AASHTO.

POST-MEETING ADDITION BY RON HUGHES:

7. A well-defined approach for the systematic identification of system requirements, development of system/treatment concepts, the preliminary evaluation of concepts using modeling and simulation, the development and evaluation of operational prototypes, culminating with full-scale operational evaluations under the range of conditions necessary to ensure generalizability of results.

Lois Thibault

US Access Board. Discussed the Access Board's Draft Guidelines for Roundabouts, dated June 2002. No formal presentation slides or paper was presented. Attachment No. 1 presents Section 1105.6 of the Draft Public Rights-of-Way Guidelines which specifies the requirements for roundabouts.

Janet Barlow

PowerPoint Presentation entitled, "Pedestrians with Vision Loss or Blindness." Presentation Attached (See Attachment 4, Not Included in Draft Version 2,0 of the Proceedings).

Some key facts from this presentation:

• By 2010, expect there to be 20 million visually impaired persons over age 45. Problems for people who are blind include: locating the crosswalk and detecting a gap in traffic.
  
  
• National Eye Institute of the National Institutes of Health has funded a five-year project (June 2000-May 2005) on Blind Pedestrians' Access to Intersections. The project includes Roundabouts - blind and low vision individuals, Accessible Pedestrian Signals, and Detectable warnings.
  
  
• The NEI Study of Roundabouts Access evaluated gap judgments by sighted and blind individuals at 5 roundabouts with volumes from 12,000 to 35,000 estimated AADT. The study included 2 Single lane and 3 multi-lane roundabouts. Findings thus far:
  
  
  • Higher volumes yielded fewer crossable gaps.
  • Higher volumes resulted in more unsafe judgments, more missed gaps, and longer periods of time between the beginning of a crossable gap and the point at which a blind person detected it. Blind pedestrians detected gaps later than sighted pedestrians. In Baltimore gaps were detected 3 seconds later and in Tampa, 5.5 seconds later.
    
    
• Australia. Individuals who are blind or visually impaired and Orientation and Mobility Specialists state that blind pedestrians avoid crossing at roundabouts, and roundabouts often severely limit where they can travel. In Australia, roundabouts may have detectable warnings and tactile guidestrips.

• England. Pedestrians who are blind or visually impaired state that roundabouts can be very difficult to cross. Signals are installed at some roundabout locations, as are raised crosswalks.

Presentation includes video clips of pedestrians who are blind crossing at a signalized intersection and at a roundabout, and pedestrian who is sighted crossing at a roundabout.

Ed Meyer

PowerPoint presentation entitled, ITE Working Group on Roundabout Accessibility Issues, Ed Meyer's presentation reviews the history, geometry, traffic characteristics, pedestrian needs, benefits, issues, and international use of roundabouts. A few key aspects of Ed Meyer's presentation are included below: (See Attachment 5, not included in Draft Version 2.0 of Proceedings)

1. Key roundabout features may include: (1) counterclockwise circulation; (2) splitter island; (3) circulatory roadway; (4) bicycle treatment; (5) central island; (6) sidewalk; (7) landscaping buffer; (8) yield line; (9) accessible pedestrian crossing; and (10) apron.

2. Internationally, there are about 50,000 roundabouts; there are approximately 250 to 500 roundabouts in the United States.

3. Positive aspects of roundabout include (1) speed-controlled environment, and (2) splitter island provides refuge. Negative aspects of roundabouts include (1) pedestrians must assess gaps; (2) disabled, children, and elderly may have difficulty; and (3) entries and exits with more than one lane are difficult to cross.

4. The presentation includes slides from the Netherlands that shows multi-modal roundabout treatments.

5. Design Guidance for visually impaired pedestrians: (1) determine optimal location and orientation of crosswalk and (2) consider application of textured pavements, raised crosswalks and use of traffic control.

6. Technological Advancements for use in roundabouts: (1) flashing beacons; (2) in-pavement flashers and (3) pedestrian signals (mid-block, actuated, pedestrian activated)

Tom Brahms

Microsoft Word document, Meeting Notes and Follow-up Suggestions from 11th September 2002 Meeting in Australia. (See Attachment 6, not included in Draft Version 1.0 of Proceedings) - coming soon

A structured approach to the need for provision of special pedestrian facilities, using warrants for a pedestrian facility, might be as follows:

- denotes no facility; Z - zebra crossing--S- Traffic Signals (typically PELICAN signals)

The idea of using "circulating + exit" flows as a variable is that visually impaired pedestrians use sound as a cue, and the sound or its absence is likely to be related not just to exiting traffic but also the circulating traffic. For crossings that may be located further than currently typical, it may be that exit flows are applicable - giving higher roundabout flows to "trigger" warrants.

(In the USA and Canada, there is a clear need to develop a set of standard pedestrian crossing facilities - such as the "zebra" signals, and PELICAN, and have those incorporated into the MUTCD, together with warrants for their use).

Potential "standards" for pedestrian facilities at roundabouts might include:

• (Except at low volume local/local roundabouts) all pedestrian crossing paths are to be located so that pedestrians pass at least 6m behind the entry holding line, or 6m beyond the outer inscribed circle for crossing exists;
  
  
• all crossing paths are to be aligned within 10 degrees of perpendicular to the building lines;
  
  
• All paths to be paved, have "pram crossing" profiles, and be DDA compliant, and no other paths are to connect the footpath to curbs adjacent to the roundabout - e.g. all redundant paths to be removed;
  
  
• Areas between the roundabout outer curbs and the footpath, and between the pedestrian crossing points are to be surfaced with a different material to that in the paths;
  
  
• a small groove is to be cut into the road pavement to define the edges of the pedestrian crossing paths as they cross the roadway to provide tactile guidance when needed.
  
  
• Where signalized crossings are provided, they should be located at least 20m from the outer inscribed circle;

Note: The above potential standards are a result of the brainstorming session held on September 11, 2002, and do not represent technical requirements of any regulatory or transportation agencies within Australia. They are presented here as one line of thinking.

John Peirce

Powerpoint Presentation, Pedestrian Crossings At Roundabouts, Roundabout Accessibility Issues Working Group Meeting, Washington October 2002. (See Attachment 7, not included in Draft Version 1.0 of Proceedings)

Use signalized crossings

• On exit, not more than 20m from roundabout
• On exit, taper should be complete before crossing
• On the entry, between 20 and 50m from roundabout

Crossing locations:

• Stagger the crossings
• Pedestrians on central reserve splitter island look towards traffic they are about to cross
• Control speed on exit from roundabout- exit deflection as opposed to "easy exit"?

Use Colored Surfaces

• Colored surface warns drivers of hazard ahead
• Surfacing material should be a high friction material
• If possible, define nationally what colour represents what hazard
• Needs maintenance to refresh colour
• Use vehicle and pedestrian detection equipment.
• BLEEP & SWEEP equipment
• Tactile revolving cone
• "Ticking boxes"
• Tactile paving surfaces

Lighting: Use uniform brightness.

Ed Morris

US Department of Transportation, Office of Civil Rights. Powerpoint Presentation, The Big Picture. How Relevant are Pedestrian Access Issues to Everyday Life. (See Attachment 8, not included in Draft Version 2.0 of Proceedings)

• Section 504 of the Rehabilitation Act prohibits Federal funding on any project that discriminates against people with disabilities

• ADA Design Minimums are the building blocks for applying better design practices

• If it is not accessible it is not safe or usable.

David Guth, Daniel Ashmead, Richard Long, et.al.

Paper entitled, "Blind Pedestrians' Vehicular Gap Detection at Roundabout Intersections," David Guth, Daniel Ashmead, Richard Long, Paul Ponchillia, & Robert Wall, Department of Blindness and Low Vision Studies, Western Michigan University. (See Attachment 9, not included in Draft Version 1.0 of Proceedings)

Abstract - We investigated the judgments of blind and sighted persons about the duration of gaps in traffic at four modern roundabout intersections. Participants stood at roundabouts' crosswalks and indicated when they believed that gaps between vehicles were adequate for crossing to the pedestrian (splitter) island in the middle of the road before the arrival of the next vehicle at the crosswalk. We analyzed participants' latencies to detect gaps, their ability to detect gaps, and the frequency with which participants erroneously indicated that a gap was long enough to cross. The findings suggest that at some roundabouts, there are differences in pedestrians' abilities to determine whether it is safe to initiate a crossing, depending on whether they are using vision and hearing or hearing alone. Further, this effect appears to be related to the volume of vehicular traffic. Preliminary findings from three of the roundabouts were presented at IMC-10. This talk will review and expand upon those findings and then present new findings from an experiment at a single-lane urban roundabout at which pedestrians made judgments during both peak-traffic (rush) hours and off-peak hours.

Attachment No. 1: Final Agenda - (Dated October 24, 2002)

Working Group Meeting on
Roundabout Accessibility Issues

October 28-29, 2002

October 28

October 29

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ATTACHMENT NO. 2: PROPOSED ACCESS BOARD GUIDELINES ON ROUNDABOUTS

Discussion of Provisions Roundabouts (1105.6)

A growing trend in roadway design favors continuous-flow roundabouts over traditional signalized intersections. While their design varies widely, roundabouts typically feature a circulatory roadway around a central island. Entering traffic yields to vehicles already in the circle. Increasingly popular in the U.S. because they add vehicle capacity and reduce delay, roundabouts are a common feature in Europe and Australia. Because crossing at a roundabout requires a pedestrian to visually select a safe gap between cars that may not stop, accessibility has been problematic. While roundabouts may be an asset to traffic planners in controlling and slowing the flow of traffic at intersections without using traffic signals, the absence of stopped traffic presents a problem for pedestrians with vision impairments in crossing streets. Pedestrians report that vehicles at roundabouts, as well as at other unsignalized crossings, often do not yield for pedestrians. Persons with vision impairments and pedestrians who may hesitate at such crossings are at a particular disadvantage.

To provide safer crossing at roundabouts, the draft guidelines would require pedestrian activated crossing signals at each roundabout crosswalk, including those at splitter islands. (The draft guidelines would ensure that such signals are usable by persons with vision impairments under requirements in section 1106 discussed below.) Although roundabouts are typically used to avoid signalization, the Board is not aware of alternatives that would allow safe passage for pedestrians with disabilities. Aside from accessibility, the use of roundabouts in areas of high pedestrian use has been questioned by some in the industry.

Requiring the signal to be pedestrian activated may help limit the impact on traffic flow. Signal technologies are available that can further minimize the impact, such as devices that halt traffic only while a pedestrian is in the crosswalk. The Board seeks information on alternative design strategies and available technologies that can improve access at roundabouts for persons with disabilities, particularly those with vision impairments.

Barriers or similarly distinct elements are needed to prevent blind persons from inadvertently crossing a roundabout roadway in unsafe locations. The draft guidelines would require a continuous barrier along the street side of the sidewalk where pedestrian crossing is prohibited. If a railing is used, it must have a bottom rail no higher than 15 inches. This dimension would allow use of a standard roadside guardrail while providing sufficient cane detectability.

Text of Draft Guidelines

1105.6 Roundabouts. Where pedestrian crosswalks and pedestrian facilities are provided at roundabouts, they shall comply with 1105.6.

1105.6.1 Separation. Continuous barriers shall be provided along the street side of the sidewalk where pedestrian crossing is prohibited. Where railings are used, they shall have a bottom rail 15 inches (380 mm) maximum above the pedestrian access route.

1105.6.2 Signals. A pedestrian activated traffic signal complying with 1106 shall be provided for each segment of the crosswalk, including the splitter island. Signals shall clearly identify which crosswalk segment the signal serves.

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ATTACHMENT NO. 3

OCTOBER 28-29, 2002

FINAL ROSTER

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