Principal Advisor to Lucknow Metro Rail Corporation E Sreedharan resigned citing health concerns, IANS reported on Monday.

“Sreedharan personally monitored the construction work of the North-South Corridor,” Lucknow Metro Director Kumar Keshav said. “His valuable guidance was crucial in construction of the underground section. I requested him not to resign but he said his health was not supporting him at this point of time.”

A few senior Lucknow Metro Rail Corporation officials have also decided to resign along with Sreedharan, Hindustan Times reported. Lucknow Metro has forwarded Sreedharan’s letter to the state government for approval.

Sreedharan was appointed the principal advisor to the Lucknow Metro Rail Corporation in February 2014. Sreedharan, famously known as the “Metro Man”, has been credited with handling several mega Metro projects in the country.

Sreedharan, a retired officer of the Indian Railway Service of Engineers, was reportedly reluctant to initially take on the role of advisor of the Lucknow Metro Rail Corporation. He reconsidered after then Chief Minister Akhilesh Yadav had personally asked him to get on board.

Sreedharan recently faced criticism for opposing theDelhi government’s proposal to offer free rides to women on the metro. In a letter to Delhi Deputy Chief Minister Manish Sisodia, Sreedharan had called the proposal an election gimmick. However, Aam Aadmi Party leader Atishi Marlena said she was surprised that Sreedharan had written a “political letter”.

Sreedharan has played a significant role in optimising land used for Metro stations. He had also advised chief engineers to implement measures to reduce expenses on the maintenance and operations of the metro, according to IANS.

Sreedharan has also played a key role in setting up the Konkan Railway and the Delhi Metro. He was awarded the Padma Shri in 2001 and Padma Vibhushan in 2008 for his contribution to transforming public transport in India.