The Delhi Metro Rail Corporation will turn over a new leaf on Friday as it begins trial runs on its longest corridor -- the 29.3 km Line III -- which when opened in December will reduce the travel time between Barakhamba Road in Connaught Place and Dwarka Sub-city to a mere 45 minutes. To gauge the preparations on the section, DMRC will start with trials between Barakhamba Road and Karol Bagh to begin with. Already the Corporation has carried out various technical checks ahead of the trials. This section also boasts of many first for Delhi Metro. It is the only one where the lines will be both elevated and underground. Also, this section would be the longest anywhere in the world to be thrown open to passenger movement and possesses the longest single piece iron bridge at Rajouri Garden, where the line while passing over a flyover reaches a height of 17.5 metres.