Canadian National Railway Co. said it’s alleviating a shortage of rail capacity for lumber shipments in British Columbia.

The largest Canadian railroad’s ability to move wood products is gradually catching up with demand following extreme winter conditions in North America this year, Emily Hamer, a Vancouver-based CN spokeswoman, said this week.

“We’re working closely with our customers on fleet availability and delivery times,” said Hamer, who declined to estimate when railcar availability in the province, Canada’s largest lumber-producing region, would return to normal. “It’s continually improving.

While a lack of rail capacity has caused lumber shipments to pile up since January, delays worsened last month because of a labor dispute involving truckers that service Port Metro Vancouver, said Peter Novak, manager of lumber sales at B.C. sawmill operator Dunkley Lumber Ltd.

“Every winter there are interruptions in service because of the cold, but it’s never been this protracted,” Novak said.

The federal government also moved last month to legislate minimum requirements for Montreal-based Canadian National and Calgary-based Canadian Pacific Railway Ltd. to help ease a backlog of grain in the prairie provinces.

Novak said Canadian National is now supplying his mill with about half of the specialized cars it needs to meet customer demand for lumber, up from about 40 percent two weeks ago.

“It’s definitely a bit of relief, but we’re not there yet,” he said. “We’re cautiously optimistic we’ll be back to normal by mid May.”