Roland Paoletti: 'The Medici of London Transport' whose Jubilee Line Extension is regarded as a masterpiece of design

Paoletti inspects the nearly completed Canada Water Jubilee Line station (Andy Hall)

Roland Paoletti was described by Architectural Review as "the Medici of London Transport" thanks to his role as chief architect of the Jubilee Line Extension (JLE), which commanded a £3.5 billion budget and was regarded as the most audacious building programme on the Tube since Charles Holden's designs on the Piccadilly Line in the 1930s. Opened in three phases during 1999, the 10-mile JLE runs from Green Park to Stratford, incorporating 11 new stations running through south and east London. Paoletti commissioned and oversaw all the individual architectural practices responsible for the stations on the line in order to ensure good design and innovation.

Paoletti wanted to break London Transport's traditional approach of engaging civil engineers to plan and calculate volumes and space with architects employed merely to "fit out" the designs by adding coloured tiles – what Norman Foster called "putting lipstick on the face of a gorilla". Dismissing the engineers as visionless "trench-diggers", Paoletti wanted to transform the journeys of commuters from the mundane to the marvellous, making the stations uplifting. He promised that "for the price of an Underground ticket you will see some of the greatest contributions to engineering and architecture worldwide."

Paoletti scoured the country to assemble his team, bringing in some of Britain's most talented architects. Their brief was to create bold, airy spaces filled with natural light. His genius lay in selecting architects who he knew understood engineering and, working alongside civil engineers, were capable of challenging them positively to raise the design bar while respecting budgets.

Each station was designed as an individual entity but linked to the others by the expressive and innovative engineering. Safety was foremost with the 1987 King's Cross fire still a vivid memory. Construction materials were picked for low combustibility and low-smoke, low-toxicity characteristics. And for the first time on the Underground all stations had platform-edge doors, to improve safety and ventilation, something Paoletti borrowed from his time with Hong Kong's underground network.

Work began in 1993 and the extension opened at the end of 1999 in time for the New Year celebrations at the Millennium Dome in North Greenwich. Six of the stations were new (Southwark, Bermondsey, Canada Water, Canary Wharf, North Greenwich and Canning Town), while five were enlarged and/or rebuilt (Green Park, Waterloo, London Bridge, West Ham and Westminster). The 11 monumental structures, built from hundreds of millions of tons of magnificently formed and crafted concrete, cast-iron, pressed-aluminium, brick, glass and stainless steel, had their roots in Brunel and Bazalgette, the great structural engineers of the previous century. A new fleet of six-car trains was built, able to carry 50,000 commuters per hour; the line now carries more than 127 million passengers a year.

The stations were regarded as a triumph, with Norman Foster's Canary Wharf seen as the centrepiece. It is designed to handle more than 40,000 commuters per hour, yet above ground there is little sign of the cavernous interior. Two curved glass canopies at the east and west ends cover the entrances and allow daylight to flood into the ticket hall. It is clearly a homage to Pier Luigi Nervi; it resembles his greatest work (airship hangars and sports stadia steeped in the spirit of Rome yet making use of new materials and technology), seen through a 1990s lens. "Everybody keeps saying that it's like a cathedral," Paoletti complained. "They're wrong. It actually is a cathedral."

Paoletti's own stations, Waterloo and London Bridge (with Weston Williamson), are striking arrangements of grand passageways and under-crofts – not skulking, urine-reeking alleys but the internal streets of splendidly engineered Roman markets revisited in what is, below the surface and to Paoletti's delight, Roman London. "There can have been few occasions," said Andrew Saint, Cambridge University Professor of Architecture, "when London has seen so many aspiring works of architecture on the same theme opening simultaneously. A parallel with the City churches built after the Great Fire is not out of place ... Paoletti's contribution, among others, is considerable. Perhaps the JLE achievement would have been impossible without such an inspired outsider working on it."

Born in London in 1931 to a Franco-Hungarian mother and an Italian father, he was evacuated to Scotland when war broke out. In 1942 he left for Ireland, where he was educated by Jesuits at Clongowes Wood College. He trained as an architect at Manchester University. He was introduced to Basil Spence, architect of the new Coventry Cathedral, who invited him to work for him. He moved to the University of Venice to continue his postgraduate studies, where he was inspired by architects as Carlo Scarpa, Ignacio Gardella and Ernesto Rogers, uncle of Lord Rogers of Riverside.

Shortly after, Spence asked him to work on the design of the much-delayed British Embassy in Rome, which was to be overseen by Paoletti's hero Nervi, the great architect-engineer. Government cuts halted the project but Nervi took on Paoletti anyway. This was a decisive period in Paoletti's career and would influence much of his work. Nervi's was the ultimate "design and build" practice, in which engineer, architect and contractor were rolled into one.

In 1967, Nervi received the Gold Medal from the Institution of Structural Engineers and Paoletti accompanied him to London. He gave Nervi's keynote lecture, emphasising Nervi's belief that the twin disciplines of engineering and architecture should not be divided. In 1975 he joined the Hong Kong Transit Authority as chief architect, supervising the design and construction of 37 underground stations and three depots, on time and on budget. It worked with peerless efficiency and was his passport to the JLE, via Wilfred Newton, chief accountant of the Hong Kong Mass Transit Authority, who was appointed chairman of London Transport in 1990. Paeoletti also lectured at the LSE; explaining his approach to designing railways, he said, "They are like jazz, continuous improvisation, and are only as good as the band that is improvising the tune."

Roland Romano Paoletti, architect: born London 23 April 1931; CBE 2000; married Nora; died 13 November 2013.