Comments on: More controls creates more risk?

By: Iang

Iang — Fri, 06 Jul 2007 05:55:48 +0000

The problem is complex because there are both more controls and more people involved.
The way the military address this complexity is to assign a safety officer with over-riding power. That is, the safety officer is totally responsible for the safety and only the safety, others run the operation, he just looks at the safety.
(There are other techniques too…)

By: Anonymous Coward

Anonymous Coward — Mon, 02 Jul 2007 13:19:33 +0000

“When you fully lock it the disposal motor engages. Essentially its impossible to start if you have your hand in the hole.”
In the case of a large carrot or other long cylindrical food item, would not then the user be required to reduce the size of the food item? If the user were particularly weak-handed, the logical solution to get the item in the hole would be to brandish a sharp blade and cut the item asunder.
Surely there are more instances of users of knives in a kitchen setting being injured than there are of users of garbage disposals?
You are correct, however, in the design of the control being more critical than sheer numbers of poorly designed controls. The goal, in this case, is to prevent the disposal mechanism from activating when a person’s hand is in the hole, right? Would it not make sense to remove functionality of the device while the user is engaging in risky behavior and not induce further risky behavior to meet the requirements of your control?
I present for your consideration, the lowly momentary switch in the form of a fail-safe button.
While the user is at the sink and reaching into the hole, a button on the vertical face of the sink is depressed by the user as they lean in to reach. Regardless of the position of the power switch, the depression of the fail-safe button disengages power at the source.

By: Mark Curphey

Mark Curphey — Mon, 02 Jul 2007 04:13:13 +0000

Maybe its the design of the control and not the quantity? Take the waste disposal for example. In Europe most of the waste disposals have a plug that you insert into the hole. It twists on and connects / locks. When you fully lock it the disposal motor engages. Essentially its impossible to start if you have your hand in the hole.

By: Chris

Chris — Sun, 01 Jul 2007 22:36:59 +0000

The disposal thing is safe enough as it is. If your hand is in the darn thing, you are highly motivated not to turn it on. The drill press example is a good one — I remember seeing such a control on some kind of metal-cutting gizmo, and I remember thinking “I’m glad THAT is there”.
In the amusement park case, requiring two simultaneous or near-simultaneous operations at two locations sufficiently distant to preclude activation by only one person would seem to be worthy of investigation, if only for the “most dangerous” rides. I don’t know how much attendants at Playland get paid, but if it is 15 bucks per hour and the season is 1500 hours long, you’re looking at a cost increase of about 25K per additional attendant. I’d guesstimate that Playland has maybe 10 rides that could kill a person. They have had two deaths in four years (I do not count the ones involving boats). As long as each death costs Playland more than 10*25K*2, the additional switch and attendant makes sense (even by this cold-blooded calculus). Sounds to me like installing that second switch, and hiring somebody to throw it, is worth looking at.
Full disclosure: I’ve been to Playland and paid no attention to their safety measures. For all I know, they have this very system in place.

By: Andy Steingruebl

Andy Steingruebl — Sun, 01 Jul 2007 21:02:25 +0000

The common solution to some of these types of situations is affirmative two-handed controls. For example, most drill presses and other industrial equipment requires the user have both hands on two controls simultaneously when activating them.
Ever since the bogus Audi-5000 “sudden unexplained acceleration” cases of the mid-1980′s you’ve had to have your foot on the brake to switch from Park into another gear in an automatic transmission. Cards with a manual transmission require the user to have their foot on the clutch before the starter will engage, regardless of what gear the car is in (or neutral.)
Plenty of examples of this when we believe the risk warrants it and probably some where the manufacturer was simply paranoid of lawsuits.
Perhaps garbage disposals aren’t in the same category?