Days after a fiery two-vehicle crash on the highway between Edmonton and Fort McMurray left seven dead, the province is responding to growing pressure to speed up work to twin the deadly stretch of road.

Deputy Premier Doug Horner responded to the growing outcry on social media to separate the north and southbound lanes of Highway 63, and called Friday's crash a tragedy, but also said he can't give a timeline for when the roadway will be completed.

Horner told CTV News crews are dealing with marshland along the route, which has seriously slowed work.

"If you've got a bottomless bog, how do you fill that?" Horner said. "So they've got to do some interesting things there.

"You've got to make sure the highway is safe when it's complete too, because you don't want the bottom falling out of it."

Regardless, Horner said the Redford government is doing the best it can. Since 2006, about 33 kilometres of Highway 63 has been twinned, with another 36 kilometres set to be completed by the fall.

"If it was in the premier's power to wave her wand today and have it twinned, it would be done," Horner said. "That's not in her power, but it is a priority of this government."

Since Friday, thousands of Albertans have joined in the call on social media, by following a Facebook group, signing an online petition, and writing public comments and letters to Premier Alison Redford – saying work on the highway is not going fast enough – the new official opposition agrees.

"If they continue at this rate, they're not going to be done for 70 years," Wildrose Leader and Leader of the Official Opposition Danielle Smith said. "Making it a priority means actually delivering on twinning it."

As for the fallout from the tragic crash, Horner says the loss of life was painful to hear about, and he said he would look into fast-tracking the route – but worries it might not be possible.

The Deputy Premier told CTV News he will meet with transportation officials and both of Fort McMurray's MLAs to see if there could be ways for the process to speed up. Horner also responded to allegations stating the project needs more money, he said it doesn't – the timeline is mostly driven by environmental and terrain challenges.

"It is a tragedy, and we are working as quickly as we can to make sure those kinds of tragedies don't occur again. However, we don't know all of the factors around it right now."

With files from Sean Amato