A mystery train has been running the length of the KCR East Rail in the small hours of the morning for the past week.
It turns out it is not the much-touted new KCR Through Train (KTT) but the elusive Xinshisu, the Guangzhou Railway Corporation's hi-tech locomotive, which will run alongside the KCR train on cross-border routes from Friday, but has been putting in some early appearances.
The Xinshisu - Putonghua for 'new speed' - has been running after-hours tests for the past week to fine-tune compatibility with the KCR's tracks and platforms.
It is a high-speed X2000 train built by European conglomerate ADtranz and can reach up to 250 km/h.
The Xinshisu uses a hydraulic body-tilting mechanism to negotiate bends at a higher speed, reducing travel time by 40 to 50 per cent.
The train will arrive in Hong Kong on its official maiden trip from Guangzhou at about 3.30pm on Friday.
