The man who straightened the Tube

How an engineering draughtsman changed the way millions of people picture a city

Few designs are as widely recognised as the diagram of the London Underground. Millions of people consult it every week, and in a normal year the network handles more than a billion journeys. Its coloured lines have been printed on mugs, posters and tea towels. Yet it is a strange kind of map, because it hardly shows London at all. The Underground, the first underground passenger railway in the world, opened in 1863, when a short line of about six kilometres linked Paddington with Farringdon. Over the following decades, rival companies built new routes, and by the early twentieth century the system had spread far beyond the city centre into the fields and villages of the surrounding countryside.

The maps produced in those years followed the conventional approach. They showed the railway lines laid over a plan of the streets, with every curve and bend of the track drawn as accurately as possible. This worked well enough while the network was small, but as it expanded it created a serious problem. In the centre, dozens of stations were packed into a few square kilometres, so that their names overlapped and the lines were almost impossible to follow. In the suburbs, by contrast, stations were many kilometres apart, and a map that gave them their true positions had to be either enormous or full of empty space. In the 1920s a draughtsman named Fred Stingemore tidied up the lines and removed some of the geographical detail, but his maps still kept the Underground tied to the real shape of the city.

The solution came from a young man who was not a mapmaker at all. Harry Beck, born in 1902, was an engineering draughtsman in the Underground's signals office. His daily work involved producing diagrams of electrical circuits, in which the only things that matter are the components and the way they are connected, not their physical positions. In his spare time in 1931, Beck began to wonder whether a railway could be drawn in the same way. A traveller underground, he reasoned, cannot see the streets above. What such a person needs to know is the order of the stations, and where to change from one line to another.

The diagram he drew was radically simple. Each line was shown as a straight stretch of colour running vertically, horizontally or at 45 degrees, with bends kept to a minimum. Stations were spaced at roughly even intervals, whatever the distances between them on the ground. Most importantly, Beck gave the centre of the network far more room than its true size justified, and squeezed the outer sections of the lines to fit the page. Stations where passengers can change trains were marked with diamonds, so that they stood out at a glance. The result was uncluttered, and it was possible to find a route in seconds.

The Underground's publicity department was not convinced. In 1931 it turned the design down, judging it too radical, and it feared that travellers would be confused by a map that bore so little relation to the streets. Beck persisted, and the following year the department agreed to a small trial printing. The response from passengers was so enthusiastic that a full edition appeared in 1933, with copies numbering in the hundreds of thousands. Within a few years, nobody could imagine the Underground without it.

Beck, who was paid only a modest sum for his work, regarded the map as his own and spent almost thirty years improving it. He adjusted the spacing, redrew the interchanges and added new lines as they opened, and he carried on revising the map until 1960. By then, however, his relations with the Underground had become difficult, because other people were making changes that he considered clumsy. Since 1960 the diagram has been redrawn many times, and as lines such as the Victoria line, the Jubilee line and, more recently, the Elizabeth line have been added, it has had to accommodate far more than Beck ever imagined. His basic principles have nonetheless survived.

The diagram is not without its critics, since a map that ignores distance can be misleading. The best-known example involves Leicester Square and Covent Garden, two stations that look as though a substantial gap separates them but are in fact less than 300 metres apart, a walk of about three minutes. Plenty of passengers still take the train between them. A similar effect occurs in the suburbs, where stations that appear as close to each other as those in the centre may in reality be a long way apart. Studies of passenger behaviour suggest that some people choose longer routes because the diagram makes them look simpler.

Beck's real achievement was to see that a map should show what its users need to know, and nothing more. The principle has been copied by transport systems in cities around the world, and it has since been applied to rail networks, bus routes and many other kinds of diagram. Beck died in 1974, having lived long enough to see his sketch become one of the most imitated designs of the twentieth century.