Geotechnical Investigation and Risk Assessment at Budapest Metro Line 4
The construction of the structure of Phase1 of Budapest Metro has been completed. The geotechnical investigations carried out on the basis of the Geotechnical Base Line Report (GBR) and Risk Assessment have considerably decreased geotechnical risks. The comparison of the amount of investigations carried out before the tender and in the construction phase reflects well the efforts to ensuring a safe and economical tunnel construction process. Budapest Metro was built in a "soft ground" geotechnical environment, where the ratio between the boring lengths and the tunnel lengths was equivalent with 1.2, a number accepted and applied in practice internationally. Conscientious preparatory work and site investigations in compliance with design needs have ensured that no considerable geotechnics-based events and claims have occurred during the construction phase.