Nearly 100 people have signed up to testify before the council begins debating and then votes on which mode and route will end up being the city's preferred transit alternative, guiding transportation and other planning for decades to come.

"It's the most important council vote in decades," said Mayor Mufi Hannemann.

While the city administration and most council members already have indicated a preference for a "fixed guideway" line for rail or buses, its exact mode and route could remain in doubt right up until the vote, expected to come after a full day of testimony and debate.

The council's Transportation and Planning Committee has recommended a line that starts in Kapolei and proceeds directly to Farrington Highway, via the central Kapolei business district.

Hannemann advocates a line that starts in Kapolei but loops through Kalaeloa and past the planned University of Hawai'i-West O'ahu campus on North-South Road before heading toward town.

Once a transit decision is made, the city will be launched on a project that could see ground-breaking in 2009, a first segment operating by 2012 and an estimated 128,000 riders daily using a line running from Kapolei to the University of Hawai'i-Manoa, with a possible spur to Waikiki, by 2030.