One of the great selling points of electric vehicles is that they’re much quieter than conventional cars. But this can pose a problem for pedestrians, particularly blind ones. This is particularly true at low speeds, when there’s not much noise coming from the tires or from air rushing around the car. When a car passes slowly in a parking garage or backs out of a driveway, pedestrians can hear the engine in a conventional car, but not the quiet electric motors in electric cars.

As a result, in the last couple of years the National Federation for the Blind has been lobbying for legislation that would require such cars to emit some sort of audible warning. Now the NFB has teamed up with GM to help develop such as system for the Volt, an electric vehicle with a back-up gasoline engine for extending driving range. Representatives from the federation recently took a trip to visit the Volt to evaluate the system so far–you can see a video of the meeting here, and hear the prototype warning sound. It’s an electronically modulated version of one of the Volt’s two horns. “We don’t want it to be startling,” says Andrew Farah, the Volt’s Chief Engineer. “We want it to be more of a pleasant sound.” He says, it’s designed to sound like a gentle “excuse me” rather than a startling “hey you!”

At the meeting, one of the representatives of the NFB declared that the system was a good one, provided it gets used. Chances are, however, that the system will almost never get used. The sound isn’t automatic, something that engages at low speeds. It has to be activated by the driver. The idea is that if you find yourself driving along quietly at low speeds, you’ll flip a switch, and the horn will start clearing its throat–a sound that right now is pretty obnoxious. As an added safety bonus, your lights will also flash. I can imagine that a few well-intentioned individuals will use the feature on the first few times out. But after a little of the grating noise, they’ll switch it off.

Basically, the system seems like a way for GM to fend off lawsuits, to pass the responsibility on to drivers. It’s not going to do much to save pedestrians. But an automatic system isn’t good either. I certainly wouldn’t want to buy an electric vehicle that always makes annoying sounds at low speeds. And any sound distinctive enough to serve as a warning would be annoying.

Maybe a system that detects pedestrians and only then sends out a warning would be better. Or one that automatically applies the brakes, in case the driver isn’t paying attention. Systems already exist, but they detect cars rather than pedestrians. Such systems, however, would undoubtedly be expensive, and electric vehicles are expensive enough as it is.

I’m inclined to think the best approach is to hold drivers responsible for watching out for pedestrians. Any better ideas?