TORONTO -- Filmmakers have long dreamt about adapting Jack Kerouac's beloved 1957 book "On the Road" for the big screen, but when it came time for director Walter Salles to finally get a crack at it, he decided the project needed to wait even longer.

Inspired by Kerouac's real-life adventures with his friend Neal Cassady, the novel chronicles the booze-soaked, drug-fuelled cross-country road trips taken by young friends and lovers of the free-wheeling Beat Generation.

Soon after it was published, Kerouac tried to persuade Marlon Brando to star with him in a film version of "On the Road." Decades passed before the rights were sold to Francis Ford Coppola in 1979. Prominent directors including Jean-Luc Godard and Gus Van Sant were considered to helm the film. But it wasn't until 2004 -- when Salles released "The Motorcycle Diaries," his biopic about revolutionary Che Guevara -- that the adaptation finally began to move forward.

To help face the overwhelming pressure of filming the classic book, Salles committed to learning everything there was to know about Kerouac, his friends and the Beatnik culture that inspired the novel. He recreated the roadtrips outlined in the book and filmed a documentary along the way.

He didn't rush it -- the process took the better part of five years.

"I understood the passion I had for the book was not enough of a passport to do the adaptation immediately and this is why I did the documentary," Salles said during an interview at the Toronto International Film Festival in September.

"We met the characters of the book who are still alive, poets from the same generation as Kerouac ... it allowed me to build a much more in-depth understanding of the social, political, cultural background behind it and somehow diminished the pressure of doing (the film), because we had a much better understanding of what the film should be than in the beginning."

The ensemble cast includes Sam Riley starring as the Kerouac-inspired character Sal Paradise and Garrett Hedlund as Dean Moriarty, based on Cassady. Kristen Stewart plays Marylou, Cassady's ex-wife, while Kirsten Dunst, Viggo Mortensen, Elisabeth Moss, Amy Adams and Tom Sturridge round out the cast.

Before the film began shooting -- largely in Montreal -- Salles had his actors undergo their own research at a "beatnik camp" he organized. Over several weeks they gathered together in an apartment to read, watch films from the era, pour over archival material and get into character.

"Somedays we'd do everything together and other days we'd sit in opposite corners and be doing our own personal reading but we were doing it together," said Hedlund.

"Some days we'd literally just dance," added Stewart, who said the cast felt immense pressure to embody the real-life people behind the book's stories and satisfy fans and historians.

"Obviously there's a huge intimidation factor," she said.

"There's this process where you have to prove yourself to the people it really, really matters to."

When "On the Road" premiered at the Cannes International Film Festival last May it ran nearly two hours and 20 minutes and critics complained the film's flow and pacing were off.

Salles, who admitted to rushing the first cut that screened at Cannes, responded by trimming about 15 minutes from the film.

But he can't say which version he prefers. He's happy with both and said there was even more footage he was sorry to cut out.

"I envy musicians who are able to go on stage every night and play a song differently," said Salles.

"On the Road" opens Friday in Montreal and Toronto, and on Feb. 15 in Ottawa.