BANFF, Alta - With a steady stream of cars queuing up to enter Banff National Park as a backdrop, Prime Minister Stephen Harper announced Tuesday that his government will spend $100-million to twin a treacherous stretch of the mountain highway.

Harper said improving the 14-kilometre stretch of the Trans-Canada will bolster a key trade corridor between Alberta and British Columbia and make travelling more safe and efficient.

"When the construction is complete, travel on the highway will be safer and more reliable for tourists, residents and truckers," Harper said.

"And there will be fewer traffic tie-ups on this crucial, national commercial transportation artery."

Banff park is Canada's most visited national park, attracting more than three million people annually. And almost all those people are travelling by private vehicle or bus.

Traffic in the park has increased each year for the past decade, increasing the risk to motorists and wildlife.

A succession of horrendous traffic accidents have marred the stretch of single-lane park highway between Banff and the British Columbia boundary.

Twinning the rocky stretch of road has been a work in progress for many years.

About 50 kilometres of the highway has already been completed, with a further nine kilometres expected to be finished this fall.

Tuesday's announcement specifically targets a stretch of road west of Castle Junction.

The federal government says permitting work on this next phase will begin immediately, with clearing work starting later this year and road construction starting next spring.

Harper said twinning the Trans-Canada is part of his government's $33 billion infrastructure renewal program launched in last year's budget.

"Upgrading the Trans-Canada Highway from coast to coast is one of our highest priorities," he said. "And today's announcement is an important step forward in that plan."

The road construction will include special fencing, overpasses and underpasses in an attempt to reduce wildlife fatalities which are a major issue in the park.

Bill Fisher, director general for Parks Canada's western and northern region, said the already twinned sections have provided "significant reductions in wildlife mortality."

"Fencing of the new sections, when they're complete, and the overpass and underpass structures for wildlife will improve mobility of the animals from one side of the valley to the other."