The Anderson Committee
In 1958, the Ministry of Transport was kicked into action over road signing. Something had to be done because Britain's first motorway, the Preston Bypass, was due to open in just a few months. It was clear from the outset that the signs in the latest regulations would not be adequate for motorway traffic.
The Anderson Committee began work on developing a set of designs for motorway signing, though it didn't report in time for the opening of the Preston Bypass. The motorway was used for some time as a test bed for the draft designs that the Committee came up with. These designs were very much influenced by practices in Germany and the USA, both of which had substantial lengths of motorway, and at one point considered adopting the typeface used by the US. James Drake, instrumental in the building of the Preston Bypass, was known to advocate the use of fork-style signs as used in Germany.
The final recommendations of the Committee were for a white-on-blue colour scheme, extensive use of diagrams on signs (particularly for the standard exit 'fork' sign), and new typefaces, which had been developed specially for motorway signing by Jock Kinneir. The principal new font was a modification of the established sans-serif font Aksidenz Grotesk.
One of the crucial decisions of the Anderson Committee was to use mixed-case lettering instead of the standard uppercase. The decision was partly because lower-case was more fashionable in communications design at the time, and partly because mixed-case lettering was also being used on the most thoroughly researched traffic signing systems in the USA and Germany. The evidence for the relative legibility of all-uppercase against mixed-case lettering on signs is rather mixed to this day. The conservative view, arrived at when the California Division of Highways tested an experimental traffic sign typeface in Los Angeles (which eventually developed into Series E Modified/Lowercase, the typeface used on modern American freeway guide signs), was that mixed-case lettering made slightly more efficient use of sign area than all-uppercase lettering.