Building New Links in Budapest

The Metro Line 4 (M4) project in Budapest is the city’s largest transportation project in decades. It will link new terminals in the southwest and northeast by a number of key metro and suburban interchanges. It is being built in two stages. The first phase is budgeted at $1.5 billion and is expected to take five years, with completion in 2011. In this first phase there are 11 main construction contracts with 10 stations and 7.3 kilometers of tunnel. The second phase is another 3.2 kilometers of tunnel and four stations. The entire project is to be completed in 2013. The tunnels are being driven through densely built areas with many historic buildings, requiring 24-hour monitoring. They will also pass under the Danube, which is expected to be a challenge. Budapest’s geology, which includes a high water table, is described. There are also major differences between the Buda and Pest sides of the city. The stations are being built by open pit, top-down, and mixed construction methods. Each station has its own characteristic challenges and design needs. The deepest is located 46 meters below ground, and half its platforms will be located under the Danube’s banks. To combat the hydrological instability, ground freezing is being used. As of April 2009, 40 percent of the works on the first phase had been built, with completion still expected in 2011.