During the Second World War, the Hungarian capital Budapest was heavily bombed. After the debris was cleared the semi-derelict plots were used as open-air car parks. But with the economic upsurge following the fall of the Iron Curtain there has been increasing pressure on bringing these sites back into more economically productive use.
With sensible foresight, existing planning regulations only allow new developments for offices, shopping centres and even houses that provide adequate parking. As a result basement construction in Budapest is pretty big business.
And because these sites are usually surrounded by existing and often structurally sensitive buildings, their development often calls for involved and intricate foundation work – which perhaps explains why quite a number of Europe’s leading geotechnical contractors, such as Soletanche-Bachy, Keller and Strabag have Budapest bases.
Going back further in our brief history lesson, Budapest was historically two towns separated by the Danube, with Buda on the west side and Pest on the east.
In Buda the terrain is mountainous, rising to around 500m above sea level, whereas Pest is flat. The underlying geology is different too, with deep river deposits of sands and gravels up to 13m deep in Pest, but much shallower in Buda.
But according to Lorand Sata of HBM, the Hungarian arm of Soletanche-Bachy, which has been active in the city since the late 1980s, basement depths are determined as much by cost/benefit ratios as geological variations. He says that while a three-storey basement can be constructed using only one level of supports, basements with four or five storeys need two or sometimes three supporting levels.