The repair of the outer shell of Charles Bridge could begin within two years

Prague - The repair of the outer shell of the Charles Bridge could begin within two years. However, detailed research must precede the reconstruction, during which every stone will be examined. Some have holes up to twenty centimeters deep. The last bridge arch on the Lesser Town is in the worst condition. This was stated today by Jan Zemánek, head of the bridge management department of the Technical Road Administration.

"Heritage conservationists will examine each stone and issue a birth certificate, evaluating about 30 of its parameters. After the assessment, they will inform what will be done with each stone. Some will be replaced entirely, while in some cases, a part will be separated and replaced," Zemánek explained. According to him, the work will take about ten years, progressing arch by arch. However, the repairs will proceed from the underside of the bridge, so tourist traffic will not be disrupted in any way.

The most damaged arch over the Čertovka is currently covered from below with wood to prevent pieces of sandstone from falling off. However, according to Zemánek, it must be removed around Christmas, as the wood is already deteriorating. The bases of two statues, whose replicas are to return to the bridge, are also in poor condition. According to Zemánek, repairs will have to start with those.

Approximately ten years ago, waterproof insulation was laid on the bridge, which changed the water movement throughout the structure. Previously, builders allowed water to flow freely through the building, but due to the chemicals in the rainwater, salt, and chlorine, this was no longer possible, as it would damage the bridge. The insulation will prevent seepage. "The water that flowed there for decades, turning the bridge into a sponge, is gradually leaving. It evaporates through the walls and arches," Zemánek stated.

A new concrete slab has been created and insulation has been sprayed on. The railing was repaired using coarse sandstone, which some experts criticized due to its light color. "The entire shell, including the stones down to the riverbed, is original from various reconstructions," he added. The state of the bridge has also been affected by injections from the 1970s, as the cement mortar dries out the sandstone, thereby damaging it.

The problem with Charles Bridge, as well as with the Libeň Bridge and other Prague bridges, is warming and cooling. "In summer, they are heated by the sun but cooled from the inside. In winter, they are cooled from the outside and heated from the inside, which creates the greatest tension in the arch," Zemánek explained. The core of the bridge is not made of sandstone, but of broken tuff. However, the static condition of the bridge is very good.

Construction of the bridge began on July 9, 1357, at the instigation of Charles IV by stone master Otlín, who gained experience from building an older stone bridge in Roudnice nad Labem. "The founder of Charles Bridge was not Petr Parléř, as it is commonly believed. He was only 23 years old and did not have the right to build any structure in his name," Zemánek added. Parléř took over the construction only after Otlín's death.

Then the Stone Bridge, now known as Charles Bridge, was founded in the place of the demolished Judith Bridge. It stood on round stones similar to millstones. The facing wall was made of sandstone, while the core was made of broken Petřín tuff mixed with mortar. After the current repairs, all stones are being stored for future use. Currently, about 500 stones from the railing repair are in storage at Šutka, according to Zemánek.