Ottawa council began a final debate Tuesday afternoon on a Light Rail Transit expansion that could cost the city between $744-million and $1-billion.

Mayor Bob Chiarelli seemed confident he had the votes to see the plans through. An informal CBC News poll of councillors last week found 14 or 15 of the 21 council members said they were willing to support the line and only two categorically opposed it.

The plan would see a 29.7-kilometre, 23-station LRT line run from the University of Ottawa in the north to Barrhaven in the southwest, snaking through many neighbourhoods.

It would incorporate an existing five-station, eight-kilometre O-Train line from Greenboro to Bayview. That older section would close for two years as part of construction, scheduled to begin in the fall and end in 2009.

The LRT line would use existing CPR rail lines and rights-of-way, plus parts of an old busway and would share the street with cars and pedestrian traffic for a short stretch downtown.

The new line would be electrically powered, rather than using the diesel units currently operating on the O-Train.

Ottawa has agreed to a 15-year deal with Siemens-PCL/Dufferin to design and construct the line, pending council approval.

Critics say line too expensive, unnecessary

But the plan has its critics — including Knoxdale-Merivale Coun. Gord Hunter, who told CBC News Online in June that a silent majority of residents had started to voice some serious concerns.

"What's in it for us, other than seeing our taxes go up? Where's the benefit? It's just not there?" said Hunter. Part of the line would run through his ward.

City staff claimed in June that the bid by Siemens-PCL/Dufferin came within two per cent of the $730-million target council had previously approved.

But opponents say that figure did not include a $24-million, single track link from Beatrice into the Barrhaven Town Centre, or $220-million in maintenance and operating costs over the next 15 years.

Some business groups and public transit advocates tried to delay voting on the project until after a fall municipal election in order to open up debate on the hustings, but their efforts seem to have failed.

Three days have been set aside for debate on the project, which could come to a vote as early as Tuesday night or as late as Thursday.

Ottawa transit officials are also hoping to add an East-West LRT line from Orleans to Kanata and another line from Carling Avenue to Rideau-Montreal in future years.