Crown Bridges, Helsinki
We extracted 7,000 m3 (theoretical cubic volume) of rock at the site of As Oy Berkka.
We are building a 33-apartment residential building in a densely built urban environment in the Harju district of Helsinki. YIT's Infrastructure segment excavated space for the foundations of the building in an exceptionally challenging blasting operation. The work required careful planning and took longer to complete than a similar job in an easier location.
The plot is located in the middle of the existing building stock and the surrounding houses are quite near. The rock to be excavated was also adjacent to an apartment building built in the early part of the last century, so the rock was cut using wire sawing to reduce vibrations.
Vibrographs continuously measured vibrations as the work progressed, and during the blasting work it was carefully ensured that no people entered the area. Small charges were used for blasting.
Not all of the rock was removed by blasting, some was removed with a wedge mounted on an excavator. No accidents or near misses occurred on the site. There were 7,000 cubic metres of rock to be extracted from the 1,000 square metre plot. The work was completed on schedule in four and a half months.