1938 Child Safety Scheme of Early Cloverleaf Junction, Road Design

Introduction of the clover-leaf junction.

This is a 1938 illustration of an early clover-leaf junction that appeared in Child Safety magazine. This then-novel innovation in road design has since become a global road-building convention.

A Closer Look

This idealized view of an interchange between a major arterial road and a freeway (or perhaps more properly a parkway) takes place in Britain - note the automobiles driving on the left - as Child Safety was a British publication. The illustration demonstrates the concept behind the clover-leaf junction, which allows traffic to flow uninterrupted while vehicles enter and exit the freeway. To further exhibit the remarkable efficiency and safety of this road design, three exercises are provided to the reader at bottom.

Four Leaf Clover

The clover-leaf interchange, one of the earliest standardized designs for grade-separated highway junctions, emerged in the 1920s as a solution to increasing traffic congestion and the dangers of at-grade crossings. Its defining feature was four loop ramps allowing traffic to merge or exit without crossing opposing streams. The concept was first patented in the United States in 1916 by Arthur Hale, but the design was not realized until the Automobile Age spurred large-scale road building. The first true clover-leaf interchange opened in 1929 in Woodbridge, New Jersey, followed soon after by similar constructions in Pennsylvania and other states. Quickly adopted in Europe as well (Germany built its first clover-leaf near Cologne in 1933, and the design was incorporated into the growing Reichsautobahn network), clover-leaf functions became an iconic symbol of modern motoring.

The appearance of this work in a publication dedicated to child safety makes sense, as the defining feature of the emerging concept of freeways was the lack of at-grade crossings with existing roads, much safer than earlier roads for pedestrians, bicyclists, and others not traveling at high speeds in an automobile. Although they improved pedestrian safety, clover-leaf junctions created a new problem in that vehicles merging onto the freeway would conflict with vehicles trying to exit at the impending ramp on the other side of the crossing (a problem known as weaving), which is a major cause of highway accidents. As a result, in subsequent decades, many places in the U.S., Europe, and elsewhere have tried designs that maintain the benefits of the clover-leaf but reduce the likelihood of crashes, including the 'parclo' or partial clover-leaf. Despite these issues, early clover-leaf junctions represented a milestone in traffic engineering, embodying the ambition of interwar highway planners to make high-speed travel continuous and conflict-free.

Publication History and Census

This work was prepared by the British Cement and Concrete Association (who obviously had an interest in more interchanges being built) and published as a supplement to the November 1938 issue of the short-lived British periodical Child Safety, published in London. While there is very little information available about the magazine, it appears to have only lasted a handful of months. Neither this work nor the periodical as a whole are noted among any institutional collections.

Source

Child Safety, (London: Child Safety Publications) November 1938.    

Condition

Good. Toning and verso stabilization along center vertical fold, minor loss, stabilized, at fold intersection at center.