Downtown Seoul's traffic situation has much improved this year, mainly because of an expansion of road infrastructure, the Seoul city government said yesterday. According to a survey of 13 road sections in downtown Seoul between May 25 and 27, Seoul City found that the average speed of passenger cars reached 21.19 km per hour. Seoul City said that the number of registered passenger cars in the city grew 0.3 percent from 1998 to 2.22 million units this year, with Seoul's daily traffic volume increasing 0.9 percent to 2.57 million units.