The world is changing.  The need for smoother traffic flow seems to have
taken priority over more pedestrian friendly intersection designs, with
resulting difficulties for blind travelers when crossing at some of the
more complex intersections.  Here is an interesting article which sheds
light on the situation as it currently exists. Notice how, despite all the
mathematical ingenuity applied by a traveler without a signaling device,
his safety under this circumstance was impaired. Despite the mathematical
wizzardry, he still would not know for sure that the light had changed.

Steve

---------- Forwarded message ----------
Date: Wed, 15 Dec 1999 05:44:10 -0500
From: Charles Crawford <[log in to unmask]>
Reply-To: [log in to unmask]
To: [log in to unmask]
Subject: Article worth reading.

        The following article is an interesting report on a meeting
about accessible pedestrian signaling.  It is well worth the read.
Note that this will be published in an AER newsletter.

        Thanks to the author Donna Sauerburger for allowing me to share
 it.

-- charlie Crawford.

Text of article.

---------------------
Maryland State Highway Administration
APSs and Pilot Study
     At our last meeting we met with Tom Hicks, Director of the Office of
Traffic and Safety for Maryland's State Highway Administration (SHA) to find
out about their pilot study for Accessible Pedestrian Signals (APSs).  We
were pleased to see at the meeting Maryland SHA staff Linda Singer and
Michael Niederhauser, as well as Bruce Mangum from the Traffic Management
Center of Montgomery County's Department of Transportation.
     There were four WOMA members present.  Although we had invited the
presidents of the Maryland chapters of the National Federation of the Blind
(NFB) and the American Council of the Blind (ACB), neither were able to
attend.  However three members of the NFB came: Curtis Chong, coordinator of
the NFB Technology Center in Baltimore;  Tom Bickford, author of Care and
Feeding of the Long White Cane, an NFB publication about traveling
independently, and Jennifer Tyndaal, who had requested an APS at her
neighborhood intersection (see our last newsletter).  Also present were
Margaret Buzzard, who had also requested an APS at an intersection near her,
and Lois Thibault from the U.S. Access Board.

Maryland SHA and APSs
     Mr. Hicks explained that he has been interested in the subject of APSs
for about 8 years, when they installed a trial APS in Fredericksburg that
sounded like a truck backing up.  However he observed no consumer interest
in APS until about 5 years ago.  There are presently no standards for APSs,
and he speculated that if there were indeed a need for APSs, there would
have been standards by now.
     He explained that engineers must follow the Manual on Uniform Traffic
Control Devices (MUTCD), which is now being revised.   Standards and
guidelines for APSs are in the revised draft of the manual, which will go
out for comment and voting before the final draft is ready next year.
     Mr. Hicks also said that although the Maryland SHA is completing the
APS pilot study, they will wait for national standards to be established
before installing any more APSs.  He said that it is important that there be
uniformity and consistency in APSs before they are installed, just as there
is uniformity in the traffic signals among the states (green means "go," and
red means "stop").
     Consistency would indeed be very helpful.  For example, there is
presently inconsistency in the pedestrian signals for sighted pedestrians,
and it is confusing.  In Maryland, it's hard to know which street the
pedestrian button is for unless a sign is installed (which is often not the
case) because sometimes it faces the street it is intended for crossing, and
sometimes it is facing the other street.  Sometimes the signal shows a hand
and a man walking, sometimes it shows the words "stop" and "walk."
Throughout the U.S., some places use LED displays, and experimental
pedestrian signals show graphics of eyes looking toward the cars to remind
pedestrians to watch for turning cars.  Most jurisdictions have solid white
walk signs, but Washington DC has a flashing white walk signal whenever the
pedestrian needs to watch for turning traffic, and a solid white walk signal
only when no traffic is allowed to turn in front of the pedestrian.
     As Mr. Hicks points out, there should be consistency for pedestrian
signals.  As a sighted person, I am often confused as to which street the
pedestrian button is for, and was confused when I first saw the flashing
walk signs in DC.  It could be confusing for DC residents traveling outside
their city if they don't realize that outside of DC, solid pedestrian
signals do not mean that no cars can turn in front of them.
     So consistency among the states and municipalities would definitely be
an improvement.  However consistency is not required for the pedestrian
buttons and walk signals for sighted pedestrians, so lack of consistency of
APSs should not be a reason to withhold them from blind people.
     Nevertheless, the AER Division Nine Environmental Access Committee
shares Mr. Hick's concern about consistency.  They consider it critically
important that the APS information be unambiguous, and certain
inconsistencies would make it ambiguous.  For example the locator tone for
the pedestrian button at one corner or in one city should not be confused
with the sound of the walk signal at another.  We applaud Maryland SHA and
encourage it and others to work with neighboring and national jurisdictions
to be sure there are no such potentially dangerous inconsistencies in APSs.

APS Pilot Study
     Mr. Hicks explained the pilot study briefly at the WOMA meeting, and
also sent a letter to WOMA answering our questions more specifically.  The
information presented here is from both the meeting and his letter.
     Maryland's SHA's APS pilot study originally involved three
intersections along York Road in Baltimore.  These were requested by three
blind residents, all of whom were members of the ACB of Maryland.  After the
APSs were installed, the three people reported that the APSs gave
information that may not be readily available regarding the appropriate time
to cross;  the proper crosswalk to use;  and directional guidance to the
upcurb.  Some of their comments reflected a lack of understanding of how to
use the signals. For example one of them noted that crossings could not be
completed during the audible phase of the signal, apparently not realizing
that the audible phase indicates when they can start walking, not how long
they have to complete the crossing.
     According to the letter, the pilot study was then expanded to seek
input from the NFB, and later was expanded further to install APSs at
intersections in Towson.
     These later intersections were chosen because they offered alternate
routes for getting around the Towson roundabout.  However SHA did not feel
(nor did consumer consensus indicate) that blind people needed APSs at those
intersections to cross safely.  This may explain why the responses and
feedback that were obtained from the second stage of the pilot study did not
specifically address whether the APSs were effective for resolving
difficulties for crossing intersections -- no specific difficulties were
determined to exist at the intersections where the APSs were installed, so
it is not likely that any improvement would be noted.
     Instead, the input seemed to be a survey of opinions about APSs in
general.  Input included statements that blind people do not need APSs to
travel independently, concerns about the effect that APSs might have on the
public's perception of blind people, and the possibility that blind people
would feel unsafe crossing streets that don't have APSs or, conversely, that
APSs would give blind people a false sense of security.  This false sense of
security apparently is the same false sense of security that sighted
pedestrians experience with traffic signals.  For example, one respondent to
the pilot study asked what would happen if someone ran a red light where
blind people relied on the pedestrian signal, and the same question could be
asked about sighted people who rely on pedestrian signals.
     The only comments which addressed specifics about APS and their use
were two comments which pointed out that APSs might interfere with using
traffic sounds.  These comments were that the noise of the "chirping bird"
covers up the traffic movement, and that APSs can make it difficult for
blind people to listen to where the traffic is moving to determine when it
is safe to cross.

Survey and APS Demonstration
     This concern about APSs making it difficult to hear traffic was also
raised by O&M specialists in a survey done last spring by the Environmental
Access Committee of AER's Division Nine (see Division Nine's Summer 1999
newsletter for survey results).  When Mr. Hicks finished his discussion,
Dona Sauerburger, COMS presented information which included the Division
Nine survey results, and showed a videotape of two intersections where blind
people had difficulty or were unable to cross without an APS.  She also
demonstrated three APSs -- the Polara, the Prisma, and the Panich.
     All three APSs addressed the concern of masking traffic sounds by being
responsive to ambient sound.  That is, when traffic is noisy, the APS sound
is louder, and when it's quiet, the APS volume goes down.
     In addition to responsiveness to ambient sound, all three APSs featured
tactile arrows to indicate which street the button and signal were for, a
locator tone which enabled the blind pedestrian to localize the button, and
tactile as well as auditory indications of when the WALK signal is on.  The
Prisma also had a tactile graphic that illustrated geometric features of the
street, such as the width, median strip, etc.  The Polara verbally gave the
name of the street being crossed if the button was held down for four
seconds, and offered raised-line and braille labels to name the street.
     Dona explained that her experience matches that of Mr. Hicks, who had
not heard any concerns from consumers until 5 years ago.  Dona reported that
until 5 or 10 years ago, her clients were able to cross almost all
signalized intersections safely using traditional strategies.  The reason
that the need for APSs has increased since that time is because of more
complex intersections (including actuation), quieter cars, wider streets,
and more arterial streets which must be crossed to get to or from
neighborhood entrances which provide little or no parallel traffic surges to
indicate when the signal changes.
     During the meeting, Bruce Mangum distributed a list of APSs which have
been installed at intersections that are under the jurisdiction of
Montgomery County.  His statistics bear out what Mr. Hicks and Dona said:
by 1995, there were only two APSs installed (1988 and 1991), but in the last
4 years, 5 more APSs were requested and installed.  All but one of these
were along arterials intersecting with quiet side streets, where there is
insufficient parallel traffic surges from the side street to know when the
walk signal is on.  This is the same situation at the intersections where
APSs were requested from Maryland's SHA by the two people in Dona's
videotape and by Jennifer Tyndaal.

Strategies to Cross Streets at Traffic Signals Without APSs -- Is it Safe to
Rely on Timing?
     For years, WOMA and individual O&M specialists have struggled
unsuccessfully to come up with alternative strategies to enable people to
cross safely without APSs at modern intersections where traditional
strategies aren't sufficient.  We asked the NFB of Maryland, which opposes
wholesale use of APSs, to help us figure out how blind people can cross
certain intersections without them. We would also welcome ideas from the
traffic engineers for how blind people can recognize when their pedestrian
signal is on at difficult intersections where they refuse to install APSs.
     In response to our request to the NFB, Tom Bickford graciously took the
time to observe and assess a typically difficult intersection along an
arterial, and proposed a strategy to cross without using an APS.
      The intersection which he assessed was the one for which Jennifer
Tyndaal had requested an APS.  It is on Riggs Road, which is 7 lanes wide,
and the problem was insufficient traffic from the side street.  Mr.
Bickford's solution was a variation of a strategy that has been tried
occasionally by O&M specialists.  This strategy is to time the traffic
signal to predict when it's going to change.
     In general, the strategy of timing the signal works like this.  First,
you observe that your walk signal or green light comes on at a certain time
after another event, for example 17 seconds after the left-turning traffic
on the parallel street starts, or 25 seconds after the perpendicular traffic
starts.  Then, when the observed event occurs, you start counting seconds
until you assume your signal starts, and you begin crossing.
     Being able to use this strategy requires that:
1) the timing of the cycle is reliable and predictable;
2) you can consistently and accurately measure time (the longer the time
being measured, the more difficult this is); and
3) you have the cognitive ability to understand the procedure and remember
the required timing accurately each time you use it, regardless of how long
ago you used it last.
     The last two requirements can be met by many independent travelers who
are visually impaired, although this strategy leaves out visually impaired
people who have problems with memory or understanding complex procedures, or
who cannot accurately and consistently measure the timing.
     Nevertheless, let's look at the first criterion, to see if this might
be a viable strategy for those who are capable of using it.  That criterion
is that the timing of the cycle must be reliable and predictable in order
for timing strategies to be reliable.
     This means that the cycle must either be fixed-time or, if it's
actuated, all possible factors that could affect the timing must be
considered.  Most city intersections are fixed-time, but in the suburbs it
is very risky to assume that a signal is fixed-time, even if observations
indicate that it is.  For example if you assess an actuated intersection at
5:00 PM you might incorrectly conclude that it is fixed-time because most
actuated intersections appear to be fixed-time during rush hour, and many
intersections are fixed-time during the day and actuated in the evening.
     Even if a traffic engineer confirms that the signal is fixed-time 24
hours a day, engineers can change signals from fixed-time to actuation in a
twinkling at any time, or they may leave it fixed-time but change the timing
of the different phases.  When they make these changes, the engineers do not
send out public notices, nor contact all blind travelers whose safety
depends on this knowledge and who may assume that the signal is still
fixed-time or that the time of each phase is the same as it was.
     Thus it is not advisable to have our safety depend on a timing system
that relies on intersections being fixed-time with the time of the phases
never changing.  Can we develop timing strategies at actuated intersections?

Timing Actuated Intersections to Predict Walk Signals
    The situation for which Mr. Bickford was asked to find a solution was an
actuated intersection, and he came up with a variation on the strategy of
timing the signal.  On the face of it, he seems to have taken into
consideration all the factors that could affect the timing.  He observed
that the street being crossed, Riggs Road, had a minimum time for its green
light, so that when the pedestrian button is pushed to cross Riggs Road, its
light does not change until Riggs Road has its minimum time.  This minimum
time is 45 seconds.  That is, if the pedestrian button is pushed less than
45 seconds after the light for Riggs Road is red, the light will not change
again until Riggs Road has had at least 45 seconds of green.
     Mr. Bickford observed that if a minute passes without the light for
Riggs Road being red, the light for Riggs Road will turn yellow as soon as
the pedestrian button is pushed, and exactly 10 seconds later, the walk
signal to cross Riggs Road begins.  It did this consistently the entire time
he was there.
     Using his strategy, then, the pedestrian would wait until Riggs Road
had the green light for at least a minute, then push the pedestrian button
and count ten seconds while preparing to cross.  At the end of ten seconds,
the pedestrian simply assumes that the walk signal is on, and starts to cross.
     Before we can teach our students to trust timing strategies such as
this one, we must assure that every possible factor is taken into
consideration, and that there is no possibility that something could go
wrong without the pedestrian realizing it.  Unfortunately, this strategy
does not consider every factor, and things could very possibly go wrong.
     For example, Mr. Bickford's strategy requires that the pedestrians
realize whenever the light for Riggs changes to red, because they must wait
at least a minute after the light is red before they push the pedestrian
button.  But the signal can change without the blind pedestrian realizing
it, as explained here.
     After Riggs Road has had its minimum of 45 seconds of green light,
whenever a car passes over the sensors on the side street, the light for
Riggs Road turns to yellow and red.  This happens even when the car is not
coming from the side street, but rather is turning left from Riggs Road and
cuts the corner so closely that it rides over the sensors.  This happened
several times while I was there with Jennifer.  Rather frequently, then,
even when there is no car waiting on the side street, the light for Riggs
Road turns red.
     This would be no problem if the traffic on Riggs stopped so the blind
pedestrian would realize the light changed.  She'd then know that she has to
wait another minute before pressing the pedestrian button.  However, if
there is a gap in traffic on Riggs Road during the red light, no cars will
stop, and the blind pedestrian won't realize the light for Riggs had changed
to red and back to green again.
     This could happen very easily.  The light for Riggs is red for only ten
seconds (unless there is more than one car waiting at the side street).  So
if it turns red during a gap in traffic on Riggs Road that is 10 seconds or
longer, the blind person will never know the light had changed.
    Because of traffic signals within a half mile in each direction, there
are many gaps in traffic on Riggs Road that are much longer than 10 seconds,
even during busy times of the day.  During one 15-minute observation of
Riggs traffic on a weekday afternoon, there were 26 gaps -- almost two every
minute.  The gaps each lasted from 5 to 22 seconds, with the average gap
being 13 seconds.  Seventeen of the gaps were 10 seconds or longer, which is
more than one such gap every minute.
     If a car from Riggs Road drove over the sensors at the beginning of one
of these gaps (which is very likely if the driver was waiting for a gap to
turn left into the side street), the light would turn red for Riggs Road
without the pedestrian even knowing it because there would be no cars on
Riggs to stop.  If the pedestrian pushed the button within a minute of that
car driving over the sensors, the walk signal would NOT come on in ten
seconds, it would come after Riggs Road had 45 seconds of green.
     However because the pedestrian would be under faulty assumptions based
on unpredictable features, she might start to walk across a seven-lane
street during a red light.

Can We Rely on Assumptions about Signals?
     This is just one scenario in which assumptions about the signal could
be erroneous.  There are a number of ways in which actuated signals become
dysfunctional and therefore unpredictable.  For example whenever the
actuation wires in the street are cut during road repair or construction,
the signal reverts back to fixed-time until it is repaired again, which
often takes months.  During this time, Mr. Bickford's 10-second strategy
would not work because the green signal would not come on 10 seconds after
the button was pushed, it would come on at regular intervals regardless of
the button. The pedestrian relying on this strategy would have to be very
attentive, intelligent and knowledgeable enough about traffic signals and
actuation to understand all the possible ramifications and realize when the
strategy will not be effective.
     I think very few of us understand the workings of the signals enough to
predict everything that could happen.  I have studied, observed, and dealt
with actuation for at least 5 years, and attended sessions with traffic
engineers to try to understand how the system works, including the WOMA
session with engineers several years ago.  Yet every time I think I finally
understand actuation and how it works, I am dismayed to find an exception to
the rule, a situation which I had not predicted.
     For example, at our WOMA meeting at Maryland's SHA last month, in
response to a question from one of the blind travelers, the engineers
explained that if you push a pedestrian button when the light to cross your
street is green, the walk signal will not come on right away, it will come
on during the next cycle.  This is what I had been teaching my clients for
years, until two years ago when I encountered an exception to the rule.
     What I discovered is that this rule is not true if you are crossing a
secondary street at a fully actuated signal (that is, where there are walk
signals and pedestrian buttons for both streets).  Sometimes in that
situation, if you push the pedestrian button during a green light, the walk
signal does comes on immediately, not during the next cycle.  When they were
asked about it, the engineers at first said this wasn't the case, then
reconsidered and realized that it was true.
     What other exceptions to the rules exist which we haven't observed and
which engineers may forget to tell us?  How can we teach our students to use
timing to predict when their walk signal will begin when the system is so
complex, and there are unknown exceptions to the rules?  And do our students
need to be very intelligent and have degrees in traffic engineering in order
to understand and remember all the rules and exceptions and predictions in
order to guess what signal information is being provided to sighted drivers
and pedestrians?  There is too much possibility for error, either because of
misunderstanding or not applying the rules correctly, or because of
exceptions to the rules that we were not aware of.

How Can Blind People Cross Difficult Streets Without APSs?
     We are very grateful to the NFB of Maryland, and in particular to Mr.
Tom Bickford for trying to help us figure out how to teach people to cross
safely without APSs.  We also appreciate the expertise and consideration of
the engineers from Maryland's State Highway Administration and Montgomery
County.  We are all working on the same goals -- safe, dignified,
independent travel for people who are visually impaired.
     However, in spite of all our combined efforts, resources, and
expertise, we have not yet figured out how blind people can reliably get
signal information in some situations without an APS.

End of text


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