WINDSOR, Ont. — Backers of a proposed $400-million Detroit River rail tunnel announced Thursday they have launched the first steps toward construction.

CP Railway, Borealis Infrastructure and the Windsor Port Authority have joined together to work on building a new double-stack high-clearance tunnel to replace the existing rail freight tunnel constructed in 1909.

Formerly known as the Detroit River Tunnel Project and Jobs Tunnel, the new name for the project is the Continental Rail Gateway. An environmental assessment description has been filed with the federal Transportation ministry.

Once environmental approvals are in place -- proponents expect them to take about 18 months -- the project will take three years to build and promises 2,200 direct and indirect construction jobs.

"A larger replacement rail tunnel is critical to creating jobs and turning Windsor-Detroit into one of the most significant logistics hubs in the Midwest," said David Cree, president/CEO of the port authority.

A new rail tunnel for Windsor has been touted for nearly 10 years, but the former DRTP got bogged down by controversy and neighbourhood opposition when the plan included conversion of a South Windsor rail corridor and tunnel into use by trucks.

That plan was pulled off the table several years ago and CP and Borealis have since focused on building a larger rail tunnel next to the existing tube to handle CP's growing fleet of double-stacked, three-metre-high rail containers and multi-level rail cars.

The existing tunnel -- which annually carries 350,000 cars and $21.5 billion in trade -- was enlarged in 1994, but cannot be expanded further.

The number of larger cars -- many originating out of the Port of Montreal -- has reached the point where a new tunnel is a necessity in Windsor to get freight into the U.S., said rail tunnel proponents.

The tunnel will allow CP Rail to better compete for business with a larger Sarnia-Port Huron rail tunnel owned by competitor CN Rail. That tunnel was constructed in the mid-1990s.