Train 18, which has already gained a maximum speed of 180kmph during trials, will leave for Prayag Raj, formerly known as Allahabad, at 00.55 am Saturday for yet another trial run to the holy city in preparation for its commercial run on the route from January, a senior official said. Prime Minister Narendra Modi is expected to flag off the train by mid-January, the official said.It is expected to reach the holy city by 7:20am, completing the 665-km journey in six hours and 20 minutes at a speed of around 110kmph. This is approximately two hours less that what Rajdhani takes to complete the journey.