Frequently asked questions:
The issue of blind people at roundabouts has been discussed on the listserv of the TRB Joint Subcommittee on Roundabouts ANB20(3)
-- below are answers posted about some of the more common questions:
What is the difference between safety and accessibility at roundabouts?
This was posted on the Roundabout listserv by Lee A. Rodegerdts, P.E. on February 26, 2015
There appears to be continuing misunderstanding of the differences between safety and accessibility. It is true that very few pedestrian crashes have been recorded at roundabouts in the United States. There have been few fatalities of any kind at roundabouts. The safety performance is clearly positive.
Accessibility is a different matter. The way I prefer to think of it is this way: Accessibility is not dependent on the number of people using the facility, but whether each person, across the range of mobility and vision abilities, has access to and can use the transportation facility. The research has demonstrated repeatedly that certain roundabout and channelized turn lane configurations—particularly multilane entries and exits—create a situation where a blind person does not have equal access to information that a sighted person has. A sighted person can make judgments based on their visual observations; a blind person must rely on their hearing. The sighted person often depends on the give-and-take with the driver that is achieved with eye contact. A blind person must rely solely on auditory cues to detect and use gaps or yields. This hearing task is much more difficult at crossings of multilane facilities, to the point where the multilane facility becomes inaccessible to many blind people in a way not experienced by sighted people. It becomes a wall, a barrier, much like our limited access facilities built in the 1950s and 1960s were to the neighborhoods they bisected. The access to the two group of people is not equivalent, irrespective of the number of people or the resulting frequency of crashes for the two groups of people. This is the issue that the ADA is intended to rectify, not the safety issue we quantify in the engineering sense. And if the facility to accommodate a mode of travel is provided, it cannot discriminate against a portion of the population, per the ADA.
From an engineering perspective, I think it is important to realize that blind pedestrians have a wide range of abilities and levels of comfort traveling independently, just as sighted pedestrians do. I believe it is impossible to make every facility completely safe for everyone, and in retrofit situations it is often impractical to accommodate everyone. However, I think we can, and indeed must, make our facilities as safe, accessible, and nondiscriminatory as possible as a matter of good practice.
A signal is a method that has been demonstrated to provide this equivalent access, principally through the use of an APS (Accessible Pedestrian Signal) to provide audible information. Rapid flash beacons and raised crosswalks also show effectiveness under certain situations. A discussion of these methods and associated predictive tools are intended to be included in the final report and guidelines for NCHRP Project 03-78b that is scheduled to be completed later this year.
Another point needs to be raised about the use of signals at roundabouts. In my view, this is not an either-or situation. I believe from my review of the evidence that the safety derived at a roundabout comes largely from its geometry, not the method of control. When done properly, the shape of the roundabout physically separates movements and lowers vehicular speeds to reduce the frequency and severity of collisions. The shape is responsible for nearly eliminating the head-on and higher-speed angle crashes that plague many signalized intersections. This isn’t to say that a signal doesn’t have the potential to create an unexpected condition that could be a contributing factor to its safety performance. The YIELD sign at a roundabout is always there, whereas the indication of a signal can change with little warning. But I believe that the geometry is creating the vast majority of the safety benefit. And I believe that with good engineering we can make signals at roundabouts visible and use our best timing and/or detection techniques to minimize the likelihood of them surprising someone into making an error.
The key application where I think signals can supplement a roundabout is to change the priorities for various users at our discretion where YIELD control and normal rules of the road are insufficient. A metering signal changes the priority between various entering flows. A set of signals could provide preemption or priority for people or goods on trains or buses, or for emergency vehicles. A pedestrian signal changes the priority between people driving and people walking. With the proper shape of the roundabout in place, I believe the most severe crashes traditionally associated with signals are controlled. As a result, I think for certain situations the use of signals at roundabouts could provide the best combination of safety, accessibility, operational performance, and life-cycle cost. Let’s use our engineering skills to find the best balance while keeping our facilities usable by everyone.
Lee A. Rodegerdts, P.E.
Kittelson & Associates, Inc.
Transportation Engineering / Planning
Roundabouts are safer than traffic signals, so how can traffic signals be accessible to blind people but multilane roundabouts are not?
This is a fair question that comes up from time to time the Roundabout listserv -- my response is excerpted from a message posted July 7, 2011.
Please bear in mind that the focus
here is ACCESS, not safety. Pedestrians and drivers are supposed to follow
a system of rules and expectations when crossing streets, and they all need
to have ACCESS to the information necessary to apply the rules or meet the
expectations. So let's look at these rules / expectations at signals and at
roundabouts, and how ACCESSIBLE they are.
At signals, the rule/expectation is that pedestrians start to cross when the
signal indicates it is their turn. To use that system, pedestrians need
ACCESS to the signal information, and this information can easily be made
accessible to blind and even deaf-blind pedestrians.
Although the signal system is accessible it by no means ensures safety, as
many of you have pointed out but remember, this discussion is not about
safety, we're talking about ACCESS to the information / rules / expectations
that pedestrians need in order to use the various systems.
And the reason this is important is because having 100% safety in a crossing
system does us no good if we don't have access to information we need to USE
So, what's the information / rules / expectation for pedestrians crossing at
roundabouts? The rules may be clear (drivers yield to peds at crosswalks)
but the expectations as well as the information needed to meet those
expectations are not.
If we can infer the expectations at roundabouts from watching the drivers
and pedestrians then the expectation seems to be that the pedestrian either
crosses when there is a crossable gap or he asserts himself at the crosswalk
(perhaps putting a foot into the street) and pauses or waits to cross until
he confirms that the vehicles are yielding. We don't see pedestrians
walking across the street without looking left/right to make sure it's okay
to cross. How
many parents teach their children to cross without first looking to make
sure it's clear or the drivers in all lanes have stopped?
THOSE are the crossing expectations that are not appropriate for blind
pedestrians because blind peds do not have ACCESS to the information needed
to meet those expectations at multilane roundabouts. A number of research
projects have shown that blind people are not able to determine crossable
gaps nearly as well as sighted pedestrians. And although sighted pedestrians
usually have no trouble determining whether drivers are yielding to them,
the FHWY research in which blind subjects and I participated at a multilane
roundabout demonstrated that blind people are not able to reliably determine
when vehicles have yielded.
So, what blind pedestrians need access to so they can cross
roundabouts just like all the other pedestrians is information to determine
when there is a crossable gap and/or when drivers in all the approaching
lanes have yielded.
If our roundabouts can be designed to provide access to that information,
then blind people as well as other vulnerable pedestrians can benefit from
the safety features that roundabouts provide.
Can training enable people who are visually impaired to
cross safely at roundabouts?
A traffic engineer asked: "I wonder if
the visually impaired get the same level of training on how to cross a
roundabout as they do with signalized intersections and non-signalized
I wrote this response (excerpted from message posted on the Roundabout listserv October 13, 2005)
Roundabouts are non-signalized pedestrian crossings, and I've been struggling with the issue of teaching blind people to cross at non-signalized crossings since 1988, when a blind man and
his wife (colleagues and friends of mine) and his dog guide were all killed
crossing where there is no traffic control. The driver in the lane they were
crossing slowed down for them and they proceeded -- the driver behind that car
pulled around and sped up and killed them all [click here to read story].
Until that time, for crossing with no traffic control, such as at roundabouts, blind people were taught only two simple strategies: "cross when quiet" and "don't
cross non-residential streets where there is no traffic control" (Pogrund, Healy, Jones, Levack, Martin-Curry, Martinez, Marz, Roberson-Smith, and Urba, 1993; Jacobson, W. 1993,
LaGrow and Weessies, 1994; Allen, Courtney Barbier, Griffith, Kern, and Shaw, 1997).
Because of the tragedy, I
started analyzing whether the "cross when quiet" strategy really is effective. I
found that there are many places where it is effective and reliable, but places
where it is NOT -- places where, even when quiet, it's simply not possible to
hear the cars well enough to know it's clear to cross.
Of course, when
it's noisy, like at busy roundabouts and intersections with channelized
right-turning lanes, it's even more difficult to hear whether it's clear to
So what I teach blind people who are learning to cross at
unsignalized crossings now are the concepts that
1) there are places where you
can't tell if it's clear to cross, even when it's quiet, and
These AREN'T easy concepts to learn. I spend at least as much time
training people at unsignalized crossings as I do at signalized ones. Just
yesterday, a few hours before I read your messages about how easy it should be
to teach people to cross at unsignalized crossings, I was working with a young
visually impaired man with a cognitive disability to learn how to cross the unsignalized entrance to his development beside a busy 2-lane street (at that time of day, lots of cars came into and out of the entrance he needed to cross).
He had learned that he is safe as long as he crosses when he can't hear any
cars, and he didn't realize that this isn't true if there's noise. There was a
very loud leaf-blower nearby that masked the sound of all cars until they were
almost next to us and he had no warning about their approach. He thought that
since he couldn't hear any cars, it was safe to cross. He had to learn
about the implications of noise on his ability to hear traffic -- I will
have to teach him to recognize when it's quiet enough that he can cross, and
when it's too noisy [click here to read story].
2) at places where
you can tell it's clear when quiet, you may be unable to tell it's clear
whenever there is noise (they have to learn how much noise is too much).
He also needs to learn a concept that is even more
complicated than recognizing when it's too noisy, and that is recognizing those
places where he can't hear the cars even when it's quiet. I've developed a procedure for teaching
that concept which takes a lot of time (I'll cite those references below
also), I don't know if he'll be able to grasp it with his cognitive disability
-- I'm optimistic because he's been able to learn everything else so far, but he
tends to need very concrete, specific rules. He can learn to cross at signalized
crossings by learning simple rules (such as starting to cross when the traffic
that moves in the nearest lanes of the parallel street start to move, and scan
for cars at specific places during the crossing), but I don't know if he can
understand the subtleties of the concepts necessary for crossing at unsignalized
crossings (concepts such as realizing when it's too noisy to know it's clear to
cross, and when he can't tell it's clear even when it's quiet).
bottom line -- when you must rely on hearing instead of vision, crossing at
unsignalized crossings is a very complex issue. There is a lot that must be
taught to prepare blind people to cross places with no traffic control, like
roundabouts and channelized right-turn lanes. It's not a simple concept, the
"rules" are complicated, and not at all like crossing with vision. If
you have some ideas for strategies that we can teach that would enable blind
people to cross roundabouts safely (and you're willing to accept responsibility
/ liability that the strategy you're proposing is reliably effective, as we in
our profession must), PLEASE let us know.
References for teaching
blind people to cross at unsignalized crossings:
References that cite the traditional
strategies for blind people to "Cross when quiet" and/or "don't cross at non-residential
- Sauerburger, D (2006). "Instructional Strategies for Teaching Judgment
in Detecting Gaps for Crossing Streets with No Traffic Controls." RE:view,
- Sauerburger, D (2005). "Street-Crossings: Analyzing Risks, Developing
Strategies, and Making Decisions." Journal of Visual Impairment and Blindness,
October 2005, AFB Press, New York, NY
- Sauerburger, D (1999). "Developing Criteria and Judgment of Safety for
Crossing Streets with Gaps in Traffic" Journal of Visual Impairment and
Blindness, AFB Press, Vol 93, #7, pp. 447-450.
- Snook Hill, M and Sauerburger, D (1996). "Teaching Students to Assess
Safety for Crossing Streets Which Have No Traffic Control," in Conference
Proceedings International Mobility Conference No. 8, Tambartun National
- Sauerburger, D (1996). "Teaching and Assessing Judgment for Crossing
Streets Where There is No Traffic Control" (videotape)
- Sauerburger, D (1995). "Safety Awareness for Crossing Streets with No
Traffic Control," Journal of Visual Impairment and Blindness, AFB Press, New
York, NY, Volume 89, Number 5, pp. 423-431
- Allen, W., Courtney Barbier, A., Griffith, A., Kern, T. and Shaw, C.
(1997). Orientation and Mobility Teaching Manual: 2nd Edition. New York, New
York: CIL Publications.
- Jacobson, W. (1993). The art and science of teaching orientation and
mobility to persons with visual impairments. New York, NY: American Foundation
for the Blind.
- LaGrow, S., and Weessies, M. (1994) Orientation and mobility: Techniques
for independence. New Zealand: The Dunmore Press, Ltd.
- Pogrund, R., Healy, G., Jones, K., Levack, N., Martin-Curry, S., Martinez,
C., Marz, J., Roberson-Smith, B., and Urba, A. (1993). TAPS--An O&M
curriculum for students with visual impairments. Austin, TX: Texas School for
the Blind and Visually Impaired.
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