Ellatuvalapil Sreedharan is one of India's greatest civil engineers, the architect of the supposedly unbuildable Konkan Railway linking Mumbai and Mangalore, and, more recently, designer of the Delhi Metro system.
Now in his 70s, he was born in 1932 in a small village in the Palghat district of Kerala, Southern India. After graduating from the Government Engineering College in Kakinada he worked for a short period as a lecturer at Kerala Polytechnic before joining Indian Railways, with whom he was to remain, on and off, for the next fifty years.
His first major engineering project, in 1963, was the rebuilding of the 19th Century Pambam Railway Bridge in Tamil Nadu following its destruction by floods.
His managers set a deadline of six months for restoring the 146-span steel structure. Employing the working practices that have defined his career - streamlined management set-up, superb organization, strict discipline, complete probity - Sreedharan completed the project in 46 days, winning a Railway Minister's Award for his efforts.
For the next three decades he worked across India - including planning and designing the Kolkata (Calcutta) Metro, India's first such system - before being entrusted in 1990 with the building of the Konkan Railway, a project he has described as "magnum opus."
Completing the last major gap in the Indian Railway network, and covering some of the most challenging terrain on the sub-continent, it took seven years to construct and, when finished, comprised 760 k.m. of track, 92 tunnels and almost 2,000 bridges.
Although he officially retired from Indian Railways at the end of the project, he was brought back to oversee the building of the $2 billion, 90-station Delhi Metro, the first stage of which was completed - on budget and on time - in December 2002.
Despite being the subject of international acclaim, and winning numerous awards - he was named an "Asian Hero" by TIME - he remains a profoundly modest man.
"I am not working for recognition or public relations," he said in a recent interview. "Sometimes I find this media attention uncomfortable."
He is married with four children.