Een edit van Wouteriaans Engels.
Wellicht kan Pino nog een keer mijn Amerikaans-achtige aanpassingen in Her Majesty's English verbeteren....
The history of the Cloverleaf Interchange
How to cross motorways split-level
By Walter Brummer
Originally translated from German by René Walhout
The origin of junctions
Shortly after the idea was born to construct specially designed motorways, the question raised how these roads should cross and connect each other. Considering the limited amount of traffic in the early days of motorised traffic, conventional level-crossings were an option. The enclosed drawing originates from the 1929 magazine "Der Straßenbau" (The construction of roads).
An intensity of 1800 motorvehicles per day was rated as “heavily congested” back in 1929, a number now to be found on every town road.
Affected by development in the United States, planners foresaw heavier traffic flows might have to be managed in the future.
To achieve the biggest possible capacity, strong slow down or even full jams had to be avoided. This principle excluded level crossings. How to change from one level to another led to much debate.
On November 6, 1926 the “HAFRABA” was founded in Germany, an association which aspired to construct a motorway connecting HAmburg, FRAnkfurt and BAsel. A member of the HAFRABA board, Herman Uhlfelder from Frankfurt, designed several sketches for interchanges in 1930:
“The full crossing is the primary and most complicated issue. It will be the most frequent one, because in a motorway network crossing usually four stretches will meet. A full crossing has to deal with 12 traffic directions. This results in a crossing with 8 points of convergence, 4 rectangular crosses and 12 crosses under a blunt angle. A total of 8 points of concern and 12 danger points. Structures will only dissolve it partially. Effort should be given to remediate these issues.”
Picture: The “Gothic Interchange” with building costs estimated at 1.4 million Mark (1931) the most expensive of all. The interchange is completely free of conflicts and has only large radii. The disadvantage of the design is within the bends that disrupt the continueing directions. Ground surface: 17 hectare. Number of structures: 8.
Picture: The “Circle Interchange” (roundabout). The simplest as well as the cheapest solution. Estimated at 0.29 milllion Marks in 1931. A limited amount of ground surface and no structures. Unsuitable for modern traffic and now merely in use for the interchange of traffic on slipways.
The “Baroque Interchange” occupies 13.1 hectares and lacks sharp bends. All four left turning curves are on ground level. Number of structures: 4. Estimated building costs in 1931: 0.69 Marks.
The triple invention of the cloverleaf
The most conventional manner for motorways to cross is the so-called “cloverleaf”. Until present day all European publications refer to the Swiss Willy Sarbach as the inventor. However, the world’s first cloverleaf was constructed in 1928 nearby New York City, whose planning had taken place well ahead of Sarbach’s “invention”. This curiosity bothered Alexander Thewalt form Leipzig, Germany. After laborious examinations around the world he concluded the cloverleaf was invented simultaneously by different people on different locations. Key factor was the “rediscovery” of the 1916 patent by Arthur Hale, 11 years before Sarbach’s “invention”.
1) Arthur Hale, Maryland, USA 1916
The oldest patent for a cloverleaf was applied by engineer Arthur Hale on February 29, 1916 with number 1.173.505 at the patent office of the United States. In his application of 9 pages, Hale described 3 designs for a cloverleaf. His base design is shown on the left. The other sketches show more compact cloverleafs, which Hale had planned for urban road networks.
(Source:
http://www.uspto.gov )
In 1927, on the banks of Lake Michigan, where two main roads crossed, this grade separated junction was constructed. It shows several similarities with the third sketch from Hale’s patent.
[Source: "Highway Grade Separation in Chicago Park" article in the Engineering News Record, McGraw Hill, New York, volume 1928 (=volume 100), number 18]
2) Buenos Aires and New Jersey, first half of the 1920’s
However, the history of the cloverleaf near Woodbridge, New York leads into another direction. US-highway 1 from New York City to Philadelphia already had an intensity of 26 000 motor vehicles per day in the 1920’s.
Although the US-1 had no intersections, the busiest junctions were frequently troubled by delays and accidents. A creative solution was required.
Edward Delano from the Rudolph & Delano construction company noticed an image of an Argentinian cloverleaf in a magazine. The idea was obtained by the New Jersey road authority resulting in the construction of the well-known Woodbridge Cloverleaf as first of many.
[Source: "Clover Leaf Too Often a Bottleneck" article in the Los Angeles Times, April 7, 2004, page 12]
<< The (official) world’s first cloverleaf was built near Woodbridge in New Jersey (USA) were State Roads 4 and 25 crossed (now US1/9 and NJ35). The cloverleaf was about to be listed as monument, but the decision was made for "widening and curb replacements for both roadways, revised geometry for one ramp, placement of a center barrier on Rt. US 1&9, removal of bridge pilasters, and the addition of modern lights and guide rails." In 2004 the cloverleaf was altered significantly to improve road safety and traffic flow.
This Google Earth image shows the current presentation of the Woodbridge Cloverleaf. In seventy years only the surroundings seems to have changed.
Note from René Walhout:
<< A 1934 design for the Dutch Oudenrijn Interchange shows a remarkable resemblance with the Woodbridge Cloverleaf. Eventually, the Oudenrijn Interchange was built as a much cheaper roundabout (1939-1968).
3) Willy Sarbach, Basel, 1927
Apparently, the American invention was not noticed in Europe, so Willy Sarbach could be considered as the European inventor of the cloverleaf. He visited the 1927 HAFRABA exhibition in Basel were he observed the maps, plans, design and drawings. At home, Sarbach studied for a way to cross two motorways in a straight or aslant angle without any conflicts and with routes in all directions. It resulted in a drawing from which a 3D model was made. On December 23, 1927 Sarbach applied for a patent for his “Anlage einer Kreuzung oder Abzweigung von Autostrassen unter sich oder mit Landstrassen”. The patent was granted on October 15, 1928 under number 129222. His work was rewarded not only by HAFRABA but by the Swiss government as well. However, Sarbach didn’t do anything with his patent.
<< A model of a primal motorway cloverleaf design commissioned by HAFRABA e.V., an 1927 idea of Sarbach.
A cloverleaf owns two advantages compared to other designs: both continuing directions can cross the interchange without bending and only one central viaduct is needed.
Europe’s first cloverleaf is the Schkeuditzer Kreuz near Leipzig, Germany which opened on November 21, 1936. It took another two years before it was complete, it became fully operational on November 8, 1938.
Considering large amounts of traffic, the cloverleaf appeared not to be perfect. Left-turning vehicles must make a 270°-bend followed by merging to the left with low speed, on the same location were other traffic merges to the right to make their 270°-bend. In busy traffic this causes unsafe situations as well as traffic piling up. Another drawback is the difficulty to create multi-lane connections in the interchange. This has lead to new alternatives.
The following design is from engineer Bieligk who wrote the article “Kreuzungen von Autobahnen" which was published in the February 15, 1937 edition of "Der Straßenbau", number 4/1937.
The crossing of two motorways required a solution which excels in clarity on directions at the divergence point and in a good ratio between larger radii and ground surface.
The most essential of this solution lies within the fact that both carriageways are on different levels where they cross. This makes it possible to merge to and from any direction without detours and to continue straight on without bends. Motorists heading left use the left exit, motorists heading straight on use the centre lane and motorists heading right use the right exit.
The crossings of merging and passing lanes have been avoided by locating the left and right exits after one another, instead of on the same location. This allows merging only to the right, in accordance with the applied traffic regulations. An additional precaution for traffic using the exit coming from the passing lane can be effected by applying a diversion strip. This concerns the convergence of traffic flows on crossings as well.
When the lowest carriageway is situated on ground level, a height of 6 metres with the upper carriageway is obtained. The smallest radius at the crossing is 400 metres.
Epilogue by the author: as far as I know this type of interchange was never built.
The major challenge in designing interchanges capable of dealing with large amounts of traffic came with the mass motorisation. In the USA this started in the forties, in Europe about twenty years later. In urban areas existing structures proofed insufficient, so more creative solutions were built, particularly in the USA, where a huge amount of available ground surface was not uncommon.
The interchange between the Great Central Parkway and the Northern Boulevard near the New York World Expo was completed in 1939 and was unique in its size. [Photos from Die Betonstraße Jg.15/Nov.1940]
<< The world’s first four-level interchange was built between 1949 and 1952 in northwestern downtown Los Angeles. Here the Hollywood Freeway US-101 crosses the Harbor/Pasadena Freeway CA-110. Nowadays, with over 500.000 passing vehicles per day it is one of busiest interchanges in the world. The other two are also located in the Los Angeles area.
Information and images about larger interchanges:
Conversion of the “Mixing Bowl” south of Washington DC:
Images of Los Angeles interchanges:
Images and road maps of Los Angeles motorways:
Kurumi's Field Guide to Interchanges:
The first cloverleaf in The Netherlands
<< The “Badhoevedorp Interchange” was the first cloverleaf in The Netherlands and opened on August 8, 1967.
As early The Netherlands were with constructing motorways, so late they were with conflict free intersections. The arrears were swiftly recovered with the conversions of the Oudenrijn Interchange (13-11-1968) and the Hoevelaken Interchange (21-12-1971) into cloverleafs. Bigger and more complicated ones would soon follow.
130 km/h ? Dan haalt de trein me nog steeds in ...