I first learned to use the white cane in the late sixties
and we were taught to listen to the traffic flow which was a
common practice back then.  The signals were a lot simpler
without as many turning arrows so it was usually no problem to
know when it was safe to go for it.  In the eighties, I lived in
a direction from work that required crossing a couple of streets
that had lights.  They did have pedestrian buttons, but no
beepers.  Contrary to what you might think, busy streets are
actually safer than intermittently-used streets because you get a
constant traffic sound.  These streets were moderately busy, but
there are still long pauses in which nobody is coming from
anywhere.

	You go up, push the button, and probably set a bit on a
controller which is honored the next cycle of red for cars so
there is no way to guess when the signal actually changed.  There
are also inductive loops in the pavement which give cars the
chance to influence the flow and motorcycles fits when they don't
have enough iron to trigger the sensor.:-)

	After getting the hell scared out of me a couple of times
when there wasn't anybody around to hear, pushing the button, and
still managing to jay-walk, I called up our mayor at the time and
asked about the chances of getting some of those beepers right
here in relatively small Stillwater, Oklahoma.

	As luck would have it, the mayor was a little more
visionary than some folks in similar positions and thought it was
a great idea and, one of the Electrical Engineering classes at
Oklahoma State University was in need of a project.

	This was all back in 1983 so some of the details are a
bit fuzzy, now, but I recall, it was a record short time like
maybe a few weeks before there was a nice chirping bird sound for
North/South traffic and a video game warbling sound from one of
those Radio Shack noise maker chips for East/West streets.

	Ten years later, we moved to the other side of the campus
and I didn't have to use the audible signals any more for years.

	Fast forward to 2006.  There has been lots of new
construction on the campus and the way I normally get to work was
blocked for a while so I had to go a different direction and
begin using the audible signals once more.

	The first day I used them, something was dreadfully
wrong.  The chirping bird was still there and the video game
sound effect was now a cuckoo which is no big deal as long as the
sounds are different.  What was wrong was that in the
intervening years, somebody in their infinite wisdom reversed
the sound so that the chirping bird was now East/West and the
cuckoo is North/South.  Fortunately, the one time I got it wrong,
nobody was coming, but I was sure confused when the sound was
180-degrees out of phase with what the traffic was doing.  The
sounders and it appears, the whole system had been replaced
somewhere along the way and, I guess, there is no standard so the
moral of the story is to know what is normal for this
intersection.

	They've got those pedestrian beepers all around the
campus, now, and I always feel a little glad that I started the
ball rolling in 1983.

	I think the original beepers were wired to the 120-volt
power to the Walk light and the very first ones succumbed to a
lightning strike.  Some of the modern ones adjust their volume to
get louder when there is a lot of ambient noise so that they
don't drive permanent residents crazy by beeping loudly at 3
o'clock in the morning.

	The inductive loops I mentioned used to thoroughly jam AM
car radio reception and you could hear the carrier swish across
when the car de-tuned the loop.

Martin McCormick WB5AGZ  Stillwater, OK 
Systems Engineer
OSU Information Technology Department Network Operations Group
-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist