A pile-head plate in reinforced concrete measuring 43x8 ft., 3 ½ ft. high has 3 concrete piles in steel tubes upstream and 3 piles downstream.

The idea arised again, to build a reinforced concrete deck and put it under a roof on timber trusses. Not less than 8 projects were elaborated. Fortunately these projects met with harsh opposition of the inhabitants of Wangen, the council of Wangen and even of the Agency of Transportation. Finally the project engineer wanted to replace the stone pier of 1552 with a concrete plate on 6 concrete piles. So they had destroyed the only part of the bridge of the 16th century, as all the timber beams, planks etc. have been changed during the long bridge life of 456 years.

Fig. 5 shows one of the mighty vertical posts in oak, which most probably dates also from 1549-52. Dendrochronology has not yet been applied since now. The floor was completely replaced and 3 main-beams exchanged. They were rotten inside, what we could only find out by borings. The stone pier is slightly inclined downstreams. Mortar injections and a sheet piling around it have preserved the masonry pier of 1552. The cost was only half of the cost of a reinforced concrete construction! And amazing too: After all the work was made a load test with a 35 t truck of the army (in 1967 the legal load was 28 t) proved an adequate bearing capacity of the 415 years old construction with the highly reasonable reinforcement of 1934. During the last decades the timber floors were exposed to the water that the motor vehicles carried in by the tires. In Switzerland you find moisture even in summertime. That requires periodical replacement of bridge decks.

2005/06 there were indications about considerable movements of the river bed although the flow is slow in the tailback except when a flood occurs. Depth measurements and diver observations showed a critical state of the piles Fig. 4. The ground had lowered in 35 years since the construction of the new piers up to 16 ft. A carpet of stones of 1,000 to 2,600 lb. weight each one was put on the river bed to prevent further sinking.

2006/0 the roof was considered to have missed a general renewel for at least the last fifty years. Broken tiles and rotten timber were carefully detected and exchanged. The tiles could be found in the historic, appropriate form. The bridge deck is in the original way once again, the water from the tires runs through; a floor consisting of glued, laminated boards with an isolation and a bituminous layer on top had given an almost absolute protection for the main-beams. But it was considered too expensive. As a relief road with a new bridge was opened in 1978 trucks were banned from crossing the little town Wangen, the bus disapeared and for passenger cars a one lane width of 10 ft. and a height of 8 ft. today is sufficient.

The state of conservation of the Aare bridge of Wangen is one of the best in Switzerland and it is under the protection of the Swiss Confederation.

                          CH 3065 Bolligen, February 29, 2008 Konrad P.Meyer-Usteri

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