TIANJIN wants the private sector to build the planned Tianjin Economic and Technological Development Area (TEDA) into a complete city. Authorities envisage a 635 hectare residential and commercial city centre for the TEDA, which will act as a ''support city'' for the growing manufacturing district. Tianjin is counting on developers and the service sector to buy and develop designated sites. It also needs the private sector to build most of the accommodation and facilities. Last year, TEDA commissioned Hong Kong planners RMJM, for US$75,000, to draw up a master plan for the city centre. Tianjin is China's third largest city and the TEDA comprises a 33 square kilometre area north of Tanggu port and east of Tianjin proper. It was set up in 1984 to encourage foreign investment and has attracted over $1.7 billion in foreign investment from more than 1,000 manufacturing and service projects. Eight square metres are occupied by manufacturing. Its port location on Bohai Bay, 150 km from Beijing will make it the eastern gateway to China, said RMJM urban designer Ian Foster. Tianjin, with some help from Beijing, will build the necessary infrastructure for TEDA, such as roads, sewage, schools and 20 per cent of planned housing. A 206,875 square metre government administration complex, taking up 10 per cent of the land, will also be built. The government also plans to build a 35 km railway from Tianjin City to Bohai Bay, going through the new TEDA centre. Major roads are under construction. Completion is expected within five to 10 years, but is contingent on foreign investment and industrial growth. Large scale manufacturing is the primary activity in the area, but Tianjin wants to diversify its commercial activities. It is counting on small scale, service-oriented companies to set up shops, and financial institutions to fill up designated areas. Hong Kong businesses had shown little interest in TEDA because Tianjin was not their traditional sphere of influence, said RMJM's planning director in Hong Kong, Michael Leven.