CALGARY -- TransCanada Corp. has taken an initial step toward obtaining regulatory approval for its proposed $12-billion Energy East oil pipeline.

The Calgary-based pipeline giant (TSX:TRP) filed a project description with the National Energy Board on Tuesday -- a key step in the process.

The more than 100-page document provides details on the project based on engineering assessments, environmental studies and community consultations.

The 4,600-kilometre Energy East pipeline would connect 1.1 million barrels of western crude per day to refineries and export terminals in Quebec and New Brunswick.

It involves converting part of TransCanada's existing natural gas mainline to oil service between Alberta and Quebec and then laying new pipe the rest of the way.

TransCanada expects to file a full regulatory application for Energy East this summer, with startup expected in 2018.

Since early last year, TransCanada has met with 500 communities and 5,500 landowners.

Of the 155 First Nations and Metis communities consulted, TransCanada says 56 have so far signed letters of agreement.