Nova Scotia's environment minister has approved the environmental assessment of plans to twin 38 kilometres of Highway 104 between Sutherlands River and Addington Forks.

The project is expected to take up to five years with construction beginning later this year.

In the Jan. 29 decision, Environment Minister Margaret Miller wrote she's satisfied "any adverse effects or significant environmental effects of the undertaking can be adequately mitigated."

She attached 11 conditions that include monitoring dust and noise, and developing a plan to protect wildlife, wetlands, vegetation and water.

The Transportation Department must also plan for how to prevent and deal with erosion and any accidental spills of hazardous material.

It must also develop an archeology management plan, set up a way to respond to public complaints and seek input from the Mi'kmaw community.

The department had identified several negative environmental impacts of the project, including decreased air and water quality, increased greenhouse gas emissions and noise, and effects on habitat, at-risk species and access to land for traditional use by Mi'kmaw people.

The environment assessment received comments from federal and provincial departments, the Native Council of Nova Scotia and nine members of the public.

The stretch of highway has seen more than 400 crashes over the past decade. At least 16 people were killed in that time.

The project will include modifications to the James River interchange and the construction of a new interchange at Barneys River Station.

A new four-lane highway will be built south of the existing highway for the 10 kilometres between Barneys River Station and James River, and the remaining stretch will see the existing lanes twinned. Once the four-lane highway is built, the old roadway between Brown's Mountain Road and Pushie Road may be removed.