'Metro Man' E Sreedharan has been invited to the United Nations' High Level Advisory Group on Sustainable Transport (HLAG-ST). A DMRC press release said in Thiruvananthapuram today that Sreedharan, the Principal Advisor to Delhi Metro Rail Corporation, has been invited by the United Nations Secretary General Ban Ki-moon to serve on his HLAG-ST. The service is for a period of three years and Sreedharan has accepted the offer, it said.