by Dr. Werner Heierli
It was back in 1964 when a local contractor in the Zurich area here in Switzerland approached me with a request to optimize the design of a highway bridge north east of the city that was to be built as part of the new Federal Highway system.
At that time, I was owner and Managing Director of Heierli Engineers, a design and consulting company with focus on the construction of civil structures in the Swiss Construction Market.
I do and always did like a good challenge. The task that was laid out in front of me was clear and simple: To come up with a more economical design for a high overfilled highway bridge.
Immediately, I was taken back three years, back to the times of my Research Associate works at the Massachusetts Institute of Technology (MIT), Cambridge, Massachusetts in the US in 1961/1962.
Shortly after finishing my thesis at the Federal Institute of Technology (ETH) in Zurich, I arrived at MIT. The Cold War was at full swing and so were the US’ efforts to gain nuclear second strike capability. MIT Engineers were busy investigating methods to harden the US’ “minuteman” command structures for the launch of intercontinental ballistic missiles. Research in progress included arched and dome type shelters to resist the effects of nearby nuclear Megaton explosions. Model tests and analyses were done to assess the stability of slender arched designs, making use of the soil-structure-interaction effects to economically build high overload shelter structures.
In addition to my own research work I followed these investigations and developments with great interest.
The answer to the highway bridge problem was right there: We have to build a slender arch in precast reinforced concrete.
The idea excited the contractor such that he was willing to build a full scale test structure in one of his big gravel pits. Soon, the first BEBO test structure, 14m span by only 0.16m section thickness, was ready to be tested. We used an overload of 370 tons on one half of the arch span.
The test was successful and convinced not just the contractor, but also the Highway Authorities such that they signed the contract for the first 14m span BEBO highway bridge.
Again, a thorough load test was done on this structure once installed and overfilled. The successful completion of this test led to further contracts for a number of additional structures and then to license contracts with the first precast companies in Europe, Australia and the USA.
Many more partnerships with eligible companies around the world would follow to make BEBO a success story that lasts until today and surely for many years to come.