A train driver was killed and another injured in a derailment yesterday during a test run on the second subway line in Kunming, Yunnan province. The derailment caused an air conditioning unit to fall from the ceiling in the lead car of the train, killing the driver, according to a statement from the Kunming Rail Transit Company to Xinhua. The train's speed at the time of the accident was not given, but it is likely that the brakes had been applied as the derailment occurred when the train was approaching Lidou South Station at about 9am and was about 500 metres from the platform. There were no passengers aboard the train, and the injured co-driver was being treated in hospital, the company said. The accident occurred on a section of the Kunming South Line that was above ground. Authorities launched an investigation into the accident but would not speculate on the cause. The last reported derailment of a metro train on the mainland occurred in 2011 in Nanjing , when underground water raised part of the track. More than 500 passengers were evacuated. Yesterday's accident renewed concern about the rapid construction of metro lines in many cities. According to government figures, more than 30 cities plan to invest a total of 1 trillion yuan (HK$1.23 trillion) by 2015 on subways, with construction of most lines proceeding under tight deadlines. The massive subway construction programme has a poor workplace safety record, and yesterday's accident was the third at a subway construction site in two weeks. Five workers were killed and 18 injured when a platform collapsed at a metro parking lot in Shanghai last month, and three workers were injured in an accident in Nanjing.