Some Ottawa city councillors are expressing disappointment after learning the volume of buses continuing to use Albert and Slater streets after the city's light rail system launches won't be as low as they believed.

In May 2017 transportation manager John Manconi said he expected a 65 per cent reduction in the number of buses using the downtown transit corridor after the Confederation Line is up and running later this year.

But more current projections now peg the reduction at as little as 50 per cent.

"I guess my reaction is, is that all?" asked Coun. Jean Cloutier during a meeting of the city's transportation committee Wednesday.

City staff told councillors that while the overall reduction in volume will be about half, some sections of Albert and Slater will see less bus traffic than others.

The plan for Slater Street involves transforming the existing bus-only lane into a segregated bike lanes and wider sidewalk. (CBC) "In general, the corridor will see a reduction of the number of buses in the order of approximately 50 per cent to 60 per cent compared with existing volumes, while some segments of the Albert and Slater corridor will see a 100 per cent reduction due to the fact that no in-service buses are planned to operate along these segments," said Pat Scrimgeour, OC Transpo's director of transit customer systems and planning.

Local OC Transpo routes will still use the corridor to connect to LRT stations, but the coming migration of La Société de transport de l'Outaouais (STO) buses from Wellington Street will account for most of the transit traffic on Albert and Slater streets.

Today up to 180 buses per hour use the corridor during peak times.

Many STO routes will now end at the Lyon LRT station, where passengers will transfer to the Confederation Line.

The buses that do remain on Albert and Slater will have to coexist with other traffic after existing bus-only lanes are replaced by separated bike lanes.

City staff assured councillors the two remaining lanes will be able to handle projected traffic volumes along the corridor, including buses.