Saturday, February 24, 2007

Hybrids are so quiet they could kill the blind

OK, that was a bit of an exaggeration. Well, maybe not so much. Read on.

The Lansing, Michigan area bus provider is the Capital Area Transportation Authority, or CATA. My friend Mark Grebner worked for years to integrate the Lansing and Michigan State University bus systems. He succeeded beyond his dreams. CATA buses ramble through the campus at an amazing rate. They carry students from all corners.

The end result is an integrated town/gown bus system that enjoys huge ridership. Sometimes it seems more like a well-run streetcar service.

CATA, being a progressive organization, has invested in hybrid buses. They cost more to buy, but they use far less fuel. A few months ago, walking on campus, I noticed that they also emit far less noise.

I called Mark and mentioned that people rely on the noise that buses emit -- you hear the bus coming and you don't step off the curb. Even when driving the noise helps you stay away from these behemoths. So I proposed we should put a horn or a bell on the hybrids. Mark replied, well why not install sound emitters and pick your sound? The bus could sound like a bus, or, as Mark observed, it could pretend to be the Staten Island Ferry.

Lo and behold it turns out this is a serious issue for the blind. All Things Considered reported Thursday that the National Federation for the Blind wants hybrid cars to emit sound. The reporter waited with a blind man on a street in Washington D.C. as cars passed by. His interviewee could hear internal combustion engine cars easily. A hybrid (a Prius) went by; he did not hear it.

The advocate for the blind suggested that hybrids should emit sound at all times to make up for the missing noise. That was Mark's idea for the buses. There is technology for sending focused beams of sound, but I bet the passengers in the car could hear it, and it would drive them nuts.

I think a better answer is low-power radio. The car emits a radio signal. At busy intersections, receivers pick up the signal as hybrids go by, and in turn emit an audio warning of some sort. It could be a bell, a beep, or a vocal warning. Heck, it could take advertising. "Warning: a Prius is approaching and saving the earth." (Already at busy intersections on MSU's campus, recorded voices announce the status of Walk / Don't Walk.)

Blind people also could carry special receivers that pick up the signal anywhere. If a Prius drives by, the radio catches the signal and interrupts whatever program you're listening to. Also imagine a low-power FM network throughout a city or a campus, broadcasting location information so you know where you are.

I am betting that my friend Ron Choura, who knows more about telecom in his little finger than I will ever know, can come up with a low-power radio scheme within minutes after reading this post. And my friend Mike Hudson will probably tell me this has all been thought through.


Mark Grebner weighs in, proposing that the hybrid should emit noise but not upset the passengers. Quote:

My thought is the sound should be "plausible", not "artificial"sounding.
That is, sort of like a slightly amplified hybrid would really sound..
So if the system failed, you'd still hear (faintly) the same sound as a
car approached you.

The analogy would be power-steering or power-brakes - they both continue to
work even if not as well. Or lightly amplified opera, which is a major issue for
NY Times

Mounting a small speaker in the outer shell of the vehicle (where the
lights are) and directing the sound outward, should result in unobtrusive levels
inside the passenger compartment. And - in any event - it would just sound
like your hybrid was slightly louder than its natural level.