Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!linus!genrad!mit-eddi!smh From: smh@mit-eddi.UUCP (Steven M. Haflich) Newsgroups: net.flame Subject: Re: Another 55 mph flame Message-ID: <255@mit-eddi.UUCP> Date: Sat, 18-Jun-83 11:32:50 EDT Article-I.D.: mit-eddi.255 Posted: Sat Jun 18 11:32:50 1983 Date-Received: Sat, 18-Jun-83 22:21:05 EDT References: pur-ee.924 Lines: 60 I'm sorry if my previous argument was poorly explicated. I had intended to say something like the following: 1) If all automobile traffic were limited to a maximum speed of 5 MPH, then essentially all fatalities would be eliminated. (Well, you might still occasionally get an especially vulnerable pedestrian, but nevermind...) 2) If all "freeway" traffic were somehow forced to maintain speeds in excess of, say, 90 MPH, except when entering and exiting, then probably most drivers would succumb to serious crashes within an unacceptably short period. Now, if you replace the "magical" constraints on speed above with some notion of average traffic speed, one can hypothesize a curve relating human cost (in accidents) against average speed. Clearly, this cost, however it is measured, as nearly zero for absurdly low speeds, and unacceptably high for absurdly high speeds. We are not concerned with this cost curve at absurd speeds, but the shape of the curve at intermediate reasonable values is crucial. 55 MPH is a reasonable (that is, non-absurd) value to consider for an average traffic speed, as is 70 or 75 MPH. I ask what is the shape of the curve between these points? Is there a sharp knee somewhere in this region? If so, cost/benefit analysis might dictate *setting the average traffic speed* somewhere lower than the knee. Before anyone flames back, let me recognise the difficulties with this whole approach: 1) Laws setting a fixed upper speed limit are a Procrustian means of establishing an operating point on the curve. Certainly it would be nice to rely instead on the judgement of individual drivers. Of course I trust you, just like you trust me, but what about the other guy?... I suspect a lot of the difficulty with the 55 law is that it is a crude mechanism for *setting the average traffic speed* appropriately. 2) There is no clear way to measure costs. Lost driving time is a real issue, certainly, but how do we measure lost lives against a similar number of person-hours lost daily on the NJ Turnpike? Should they be balanced on an equal basis, assuming statistics to relate them were really available? 3) Accident statistics are mushy -- it would appear that controlled experiments are almost intrinsically impossible. Lacking really solid data, we probably just have to make rational guesses. Ugh! My best judgement is that, whenever there is other traffic within a couple hundred yards, 55 MPH is an upper limit. I have driven through Nevada at 90 MPH (before the 55 limit) and it seemed appropriate for the time and place. But if someone were to drive that speed on the Mass Pike, I would want him boiled in oil. Now a question: Does anyone have a better method for assuring (legislating) appropriate safe speeds than the blanket 55MPH we now have? I wonder if it can be done. In particular, I would not trust any law which left the matter up to the judgement of John Q. Motorist. I wouldn't doubt the good reasoned judgement of any of our colleagues who spend time improving themselves reading net.flame, but what about the other folks on the road? Steve Haflich, genrad!mit-eddie!smh P.S.: I point out again, the energy dissipated in a crash as well as the distance needed to stop both have square-law components based on speed!