TORONTO -- Fares on an express train from downtown Toronto to Pearson international airport are being slashed by more than half as it struggles to attract riders.

Since Union-Pearson Express launched in June, the one-way fare of $27.50 -- or $19 with a Presto transit card -- was decried by many as too expensive.

Transportation Minister Steven Del Duca announced the new fares of $12 and $9 on Tuesday, standing next to a sparsely filled UP Express train.

"With any new service that you put into place there's always time that's required in order to raise awareness about the service itself and to build customer loyalty," he said. "We wanted to make sure that we move forward with a plan that would help grow the ridership, in particular by making it more affordable for middle-class families and commuters across this region."

Progressive Conservative critic Michael Harris said the initial prices never should have been so high.

"We wouldn't need to be here today if the Liberals actually had listened ahead of introducing UP Express on where people felt the fares should have been in the first place," he said.

"They won't admit it, but it's clearly a step back, a mistake."

Premier Kathleen Wynne said there need to be adjustments to get people into the habit of using the service.

The Liberal government had hoped to see 5,000 riders per day by June, which would mark one year in service. In December, average daily ridership was at about 2,200.

Over the Family Day long weekend rides on the train were free and more than 40,000 people took advantage, Del Duca said.

"I'm optimistic that given how much uptake we saw over Family Day weekend, now that there's an awareness because we are dropping the fares dramatically, that more will take it and I'm hopeful that we will hit that (5,000-per-day) target," he said.

The new prices will take effect March 9, in time for the busy travel period of March break.

Commuters who want to use the UP Express to travel to or from one of the two interim stops within the city of Toronto will be charged about $5, roughly equal to a GO transit fare for the same distance.

The board of Metrolinx, the provincial transit agency that oversees the UP Express, approved the new fares at a meeting Tuesday night.

NPD Leader Andrea Horwath called the UP Express a "boondoggle" that the government now needs to ensure Metrolinx is able to save.