Mention of TRL's revolutionary speed-sensitive road hump (NCE 11 March) reflects exactly the philosophy taught to us in the early 70s.
Then, we were told, if you build humps long and flat, in the direction of travel, at (say) 20mph you experience a gentle bounce, like a humped-back bridge, but at speed you get an unforgettable jolt that cracks the suspension mountings (cars rusted a lot more then).
In practice, most calming measures now seem to be short bumps that offend at whatever speed you tackle them - hence TRL's initiative. I am not a highway engineer. Has the old passive self-regulating philosophy now been discredited?
Jon Balley (M), Littlecote, Two Dells Lane, Chesham, Bucks HP5 3QZ