Saudi Arabia’s planned Kingdom Tower will be about 50 storeys higher than the world’s tallest tower, the architect behind the superscraper has told a US television network. The building, which is backed by Saudi billionaire Prince Alwaleed, will be at least 1,000m tall and feature three sky lobbies, the most prominent placed on the 157th floor, said Adrian Smith, of architect firm Adrian Smith & Gordon Gill.The viewing platform disc that juts out from the side of the building was originally designed as a helipad and is 25 metres across.“We designed it in to the building and liked it but most pilots said it could be risky to land on, so we’ve convinced the prince, at the moment at least, that it is a pretty cool feature.” Smith said the main lessons learned from designing the Burj Khalifa that transferred over to the Kingdom tower design were around the stepped or tapered tower design.“Wind forces are significant in a tower of 1km,” he said. \"When the wind moves around a building, it creates negative pressure areas behind the building, which creates little tornados or vortices, which push the tower from side to side.“One of the ways to mitigate that is to step the tower, or slope it. Sloping is more effective but it is a little more expensive.\"Initial design images of Kingdom Tower show a mixed-used building featuring a Four Seasons hotel, an observation deck and office space, served by 59 elevators.The tower is backed by Kingdom Holdings, a subsidiary of which this month signed a $1.2bn deal with Binladin Group to construct the tower, which Prince Alwaleed described as “transformational”.At a cost of $1.2bn, the superscraper is expected to be cheaper to build than its rival, the Burj Khalifa, thanks to a decline in construction costs following the global financial crash. A report by consultancy EC Harris in July found Saudi Arabia was the cheapest Middle East country to build in, half as expensive as Bahrain and 34 percent cheaper than the UAE. From / Arabian Business News