Centre point of Japan
#Kärcher cleans the historically significant Nihonbashi Bridge in Tokyo
If credence is given to a well-known saying, all roads lead to Rome. In Japan, however, since the early seventeenth century all roads have led to the Nihonbashi Bridge. In the days of the Tokugawa shogunate, it was the starting point of all major trading routes. The majority of goods were transported along these routes, but they were also used by a large number of travellers because ships as a mode of transport were reserved exclusively for the ruling class. The bridge, built in 1603, was therefore the symbolic centre point of the country. On the roadway in the middle of the bridge, a bronze plaque still marks the point zero. The distances from and to Tokyo shown on Japanese highway signs are measured from here.
The original wooden bridge burnt down several times over the centuries, so when the bridge was last rebuilt in 1911 the material of choice was granite. However, it was not dirt-proof. As time passed, dust, mosses and algae deposits built up on the 52-metre long and 30-metre wide structure, forming encrustations up to 2 mm thick in parts. Traffic emissions from the expressway that runs across the bridge did further damage.
In order to spruce up the Nihonbashi Bridge appropriately in time for its 100th anniversary, a German-Japanese team from Kärcher took it in hand. A combination of pressure washing and low-pressure particle blasting had proven to be the most efficient and gentle beauty treatment for the granite, which was already cracked and flaking in places. Our team started by giving the bridge a preliminary clean with pressure washers and water at around 100°C. They then used GS blasting guns to carefully remove the remaining dirt and discolouration, using calcium carbonate and aluminium silicate as a blasting medium. To subject the environment to as little strain as possible we used wet and dry vacuums to vacuum up the blasting medium again immediately. Then we rinsed off any residue on the surface with HDS 13/15 hot-water pressure washers.