No risk presented by the breaking of ground occurred closed to Tétényi street

Engineers of metro 4 have checked the small surface breakings noted in the vicinity of Tétényi road metro station, which is under construction, but they mean no danger at all to nearby residents. Surface breaking occurred on January 22nd, 2008 was not significant and the defect was fixed yesterday.

During a project of this size defects may always occur, up to now no one has questioned that. Experts endeavor in any case to find forthwith and safe solutions for such problems. On Tuesday morning in the park between Tétényi road and Fejér Lipót street on the lawn area an approximately 1 m diameter surface breaking occurred along the south tunnel line, where the tunnel drill-shield had stopped for almost two weeks due to a previously planned technological break following October 18th, 2007.

Over the restarted shield there were cracked rocks and the air pressure dropped as a result of the cracked condition of rocks. Tunnel ring strengthening (second injection) was provided earlier in order to fill in the loosening. Residual loosening in the rocks reached the surface on Tuesday and it appeared as an approximately 1m deep and 1m diameter hole on the surface about 40 m away from the house No 61 on Fejér Lipót street. Hole so occurred was refilled forthwith.

Otherwise, earlier both shields had already passed by under the tall building with no concerns and no problems. Safety of the house was measured continuously by an automated monitoring system (by 15 minutes), and it is still providing measures to date also. Maximum settlement of the house is in the order of 24 mm, but this settlement value was not actually reached.

Previously, upon an initiative of the Engineers, international and home experts held a meeting for the purposes of avoiding similar events, choosing the appropriate technical solution and the appropriate ways of shield drive, optimizing the methodology, which adjusts to special situations. As a result of the discussions further tunnel construction with drill-shields is being provided in optimized mode.