The Seoul municipal government said Friday it plans to replace the city's old subway cars over the next eight years to boost the safety of its sprawling subway system and to prevent a repeat of a train collision. A total of 877 billion won (US$877.5 million) will be spent by 2022 to replace 714 subway cars used for more than 18 years with new ones equipped with a better safety device. The number accounts for some 36 percent of the 1,954 cars that run on Lines 1 through 4 run by Seoul Metro, the operator of the two trains that collided a week ago, leaving 238 people with minor injuries