The trip of a lifetime

It's no surprise, then, that as a filmmaker himself his favoured format is the road movie. His breakthrough film, Central Station, charted the journey through Brazil of a middle-aged woman and a young boy she had taken under her wing, in search of the boy's father. The Motorcycle Diaries was based on the memoir of Che Guevara, concerning the journey around South America that turned the medical student into a revolutionary. And now Salles is moving outside his Latin comfort zone to adapt an iconic work of North American fiction – and perhaps the most famous of all road trips – Jack Kerouac's On The Road.

Published in 1957, Kerouac's fictionalised account of his travels across America, notably in the speeding Hudson of his wayward pal Neal Cassady, was the work that propelled the Beat movement into the limelight. Technically, Kerouac's Benzedrine-fuelled stream of euphoric prose was formally ambitious and tremendously exciting; but the tale too was equally significant, the road representing not just a journey of self-discovery, of a writer finding his voice, but an uncovering of America itself, one of economic migrants and drifters, petty crooks and frustrated intellectuals, of which mainstream, straitlaced 1950s society was happily ignorant.

Salles first read the novel after he had returned to Brazil as a teenager, and still remembers the culture shock. "The book burst with such life and such desire for experimentation that in comparison everything else felt tame," he laughs. "You have to remember that in Brazil in the 1960s we were living under military dictatorship. On The Road, [Allen Ginsberg's poem] Howl and Beat poetry in general conveyed a sense of freedom that was everything [other than] what you could experience at the time in my country.

"If it wasn't for these pioneers, none of us would have experienced those micro-revolutions of the 1960s and early 1970s, involving sex, drugs, the expansion of the mind, the ecological movement. The Beats represented the birth of counter-culture."

Also, for him, Kerouac's work contains the bread and butter of road movies. "I believe that the most interesting road movies are the ones in which the identity crisis of the main characters mirrors the identity crisis of the culture these people originate from, or are passing through. And the characters of On The Road are seekers, challenging the conformity and conservatism that was at the heart of the McCarthy years."

The project was offered to Salles by renowned filmmaker Francis Ford Coppola, who had bought the rights to the book in 1979 but struggled for three decades to find the right combination of director, actors, script and cash to get the project moving. When Coppola saw The Motorcycle Diaries in 2004, he felt he'd found the man who might finally achieve it.

Not that it's been easy for Salles. The financial crisis, a continued and somewhat ironic lack of faith in the project by the American studios, and the director's insistence on casting unknown actors in the lead roles of Kerouac/Sal Paradise and Cassady/Dean Moriarty meant years waiting for the green light. When it came, it was due to a French, not American company; but then the French, with their affection for auteurs, have always appreciated the Brazilian.

For his part, Salles felt he needed to do something first, which was to make a documentary about the influence of the novel, called In Search Of On The Road, to help him feel his way into the feature.

"Although I knew the book well, I was aware that my cultural background wasn't sufficient grounding to direct On The Road," he explains. "The only way for me to decide whether the adaptation was possible was to immerse myself in Kerouac's world, to try to understand the impact that the Beat generation had on the American culture at the time, and what kind of impact it still has today."

To say that the 56-year-old is thorough would be an understatement. Just as he retraced Guevara's journey around South America three times for The Motorcycle Diaries, now he took Kerouac's roads – from East Coast to West, South to New Orleans and on to Mexico – with the same diligence. Along the way he interviewed surviving Beat poets, including Gary Snyder, Lawrence Ferlinghetti and Diane di Prima, and artists of subsequent generations who were influenced by the Beat movement – among them Wim Wenders, David Byrne, Laurie Anderson, Sean Penn and Johnny Depp, some of whom, says Salles, first left their home towns because they'd read On The Road or Howl.

"To tell you the truth, making the documentary would have been enough for me," he says, with surprising frankness. "I wouldn't have felt any frustration if I hadn't been able to do the feature, because the experience of meeting those poets and writers was so inspiring. They had this quality in common, which is that they all kept alive their love for what that movement represented."

What's also true is that through the documentary he discovered the enormity of the task ahead. "In most cases the America described in On The Road isn't there any more. The smaller city centres have been depopulated and industrial suburbs have mushroomed all over the country. Most of the time, it's difficult to know which city you are in – they all look the same. And the roads have been taken over by signs for McDonald's and Walmart.

"This created a major obstacle for us. We needed to go further and further to depict a country that had lost a great part of its physical identity. We covered 100,000 kilometres to shoot the film, three times more than for The Motorcycle Diaries."

More encouragingly, his research suggested the continuing relevance of the story he was about to tell. "In many ways we're living in a world that is as conservative and politically correct as the 1950s. More than anything, I think of how very contemporary On The Road is, because of the necessity to experiment that it describes, to learn from first-hand experiences and encounters. In the age of Big Brother and reality TV, when so many people live vicariously, that need seems just as urgent."

Apart from City Of God director Fernando Meirelles, no-one has done more than Salles to rejuvenate Brazilian cinema in the past 15 years. The pair commendably juggle their own international profiles with work at home, where their companies produce the films of younger Brazilian directors.

A similar sense of loyalty and community exists in the way Salles likes to keep the same collaborators on his sets. Many of the On The Road team were on the Guevara adventure, including the Puerto Rican scriptwriter Jose Rivera (who was Oscar-nominated for the earlier film) and the cameraman, composer and production designer. Alongside them, Salles has contrived an enticing international cast, using a tried and tested device of putting relative unknowns in the lead roles (so that familiarity doesn't obscure the icon), while surrounding them with established faces.

Thus the British actor Sam Riley, who made his name as Joy Division's Ian Curtis in Control, plays Paradise, and Garrett Hedlund, whose biggest role to date has been in Tron Legacy, is Moriarty; lending classy colour around them are Viggo Mortensen, Steve Buscemi and the actresses Kristen Stewart, Kirsten Dunst, Elizabeth Moss and the Brazilian Alice Braga.

Johnny Depp has stated that "we all have the film of On The Road in our heads". And Salles doesn't need to be told about the thousands of Kerouac aficionados and naysayers waiting to pounce on his choices. "Just as every person in the world has their own idea about Che, so thousands have projected their own versions of Sal Paradise and Dean Moriarty," the Brazilian admits, wryly. "I guess the only advantage that a foreign director has is that if something goes wrong, he can always find refuge in his own country."

On The Road opens on October 12