What is Involved in Constructing a Four-Lane Highway?

The process begins when MTO officials determine that a highway will soon be unable to safely handle the number of vehicles using it.

Planning is comprehensive. After extensive public consultation, MTO selects a route that is technically sound and minimizes impacts to the environment, affected property owners, businesses, and communities.

The MTO recognizes the need to manage Ontario's forests, lakes, rivers, and wildlife resources responsibly. Plans for proposed four-laning undergo a comprehensive environmental assessment process prior to approval, a process that can take two to three years to complete.

Often, four-laning is done by twinning the existing highway. This is done by constructing a new road parallel to the existing two-lane roadway and dividing northbound and southbound traffic with the use of a median.

Twinning is often not feasible in areas with concentrated populations, environmental constraints, or physical constraints because of the impacts to adjacent properties. Instead, both northbound and southbound lanes are constructed on a new alignment to minimize these impacts.

Once the route selection planning process is complete, a variety of engineering activities must take place. The proposed highway corridor and service roads are carefully surveyed. Geotechnical testing determines if the existing soils can support the highway and bridges. The roadway and bridges are designed. Finally, property required for the construction of the highway is purchased.

Proposed highway improvements are divided into discrete projects to facilitate planning, design, and construction. After environmental approvals are received, another two to three years are required from the start of engineering work to the start of construction. Each project takes, on average, two to three years to build.