Allan, the former president and CEO of ICBC, is the second high-profile opponent to pull out from the review process.
Her husband and former BC Hydro CEO Marc Eliesen also quit last fall, calling the review "a farce."
Allan says she had to leave because the review process doesn't recognize issues important to Canadians who are concerned about environmental and socio-economic risks.
"The National Energy Board is not conducting this review on a level playing field and it's not an impartial referee," she told The Early Edition's Rick Cluff.
"Regrettably, I've come to the disturbing conclusion that the outcome is predetermined and the NEB is putting the health and safety of the Canadian economy, our society and environment in harm's way."
Energy giant Kinder Morgan wants to triple the capacity of the existing Trans Mountain pipeline in Burnaby. The project would see the pipeline carry 890,000 barrels of Alberta oil to a terminal in Burnaby, where the oil will be carried off in tankers headed for Asia.
Pipeline project taken out of context
Allan accuses the National Energy Board of not considering the entire scope of the project, excluding issues like the impact of greenhouse gas from the development of the Alberta oil sands, the impact of climate change, and what would happen when "you turn English Bay and Burrard Inlet into parking lots for oil tankers."
But most importantly, Allan claims the review process is not taking into account the context of the existing 60-year-old pipeline and 13 storage tanks in Burnaby.
"When there's an earthquake, what happens when two pipelines leak into the Fraser River, not just a brand new one constructed under today's standards?" she said.
"The NEB has falsely suggested that this is just a brand new set of facilities and we'll look at them as if they're standalone, so they've excluded so much that's important to us."
Review is fair, says NEB
National Energy Board spokeswoman Tara O'Donovan says she is disappointed to hear of Allan's decision.
"As an intervenor in the process, she would have had an opportunity to influence the review of the application and by withdrawing from the process, she will no longer be able to contribute to the review or influence the board's recommendations," she said.
O'Donovan stands by the review process. With 400 intervenors and 1,300 commenters, it is designed to be flexible to meet the wide range of applications, she said.
To hear the full story, listen to the audio labelled: High-profile intervenor quits Trans Mountain review