LONDON.- The Design Museum has added 13 classics to its collection. They include a Sony Walkman, a Kalashnikov AK-47 rifle and an example of the motorway signage system, whose standardised typeface, designed by Jock Kinneir and Margaret Calvert in 1960, has not changed to this day. The road signs, commissioned by the government for Britain’s new network of motorways and major roads, were tested in 1958 in an underground car park and in Hyde Park, where they were propped against trees to determine the most effective background colours and reading distances. ‘Style never came into it,’ Calvert has said of the typeface. Calvert redesigned many of the picture signs to reflect her personal experiences. She replaced the image of a boy in a school cap leading a little girl on the school children crossing sign, with one of a girl, modelled on a photograph of herself as a child, leading a younger boy. Calvert describe