I read with great apprehension the latest activity of the inventor, Mr. Ronald Perch. He, like a great many other people, is clearly not able to understand the cause of multiple crashes in patchy fog. The problem can be expressed in terms of simple arithmetic once one appreciates the fact that the distance between two cars should be measured in terms of time, as on a race track, in which case the distance measured in feet will be a function of their speed.
Therefore if car “B” disregards the “Highway Code” and follows car “A” at an interval of half-a-second, and a speed of 60 m.p.h., then the distance between their respective front bumpers will be 44 ft. If each car then runs into a wall of dense fog or, worse still, a “Petch-meter”, and both cars slow down at the same rate, from the same spot, to a speed of 15 m.p.h., then the above distance will be reduced to 11 ft., which is most unfortunate if car “A” was 12 ft. long originally.
Taken to its ultimate conclusion if a “Petch-meter” was set to “0 mph”, then the entire rush-hour capacity of the M4 could be piled on one theoretically-predetermined spot, convenient to trash removal facilities, instead of allowing motorists to have their accidents at various sites of their own choosing, since the spacing at 0 m.p.h. is, of course, 0 ft.
It will be apparent that car “B” can avoid the accident right down to “0 m.p.h.”, if its deceleration begins 12 ft. earlier, which means a spacing of “thinking distance” plus the length of car “A” (which a “Petch-meter” cannot do). Furthermore, if car “A” suddenly joins a previous accident then the “Petch-meter” will need to have been programmed with page 8 of the “Highway Code”.
Mr. Petch was interviewed on “The World at One” January 1st and on his own admission was incapable of controlling the speed of his own car without the assistance of, first, an audible speed-warning device in his car, and later by his automatic speed regulating device. No doubt he dreams of a world of fully automatic motor cars which can be sent out on their own, while the petrified owners cringe in their armchairs at home!
Technical Secretary, Association of Healey Owners.