Raleigh, N.C. — Construction on the remainder of North Carolina's first toll road could begin as early as June.

The North Carolina Turnpike Authority's Board of Governors on Wednesday gave the green light on the 18.8-mile Triangle Expressway in Western Wake County, approving a bond proposal that allows the Turnpike Authority to seeking bond insurance and a $1 billion loan with the U.S. Department of Transportation.

"It's looking good, so, we're cautiously optimistic," said the Turnpike Authority's chief financial officer, Grady Rankin.

The Northern Wake Expressway, the first of the three sections of the Triangle Expressway, opened in July 2007 and stretches 2.8 miles from N.C. Highway 54 in Morrisville to N.C. Highway 55 near the Research Triangle Park.

The Turnpike Authority expected construction on the two remaining stretches to begin in October, but the project was delayed when the credit market collapsed.

The Turnpike Authority plans to go to the bond market in late April and could have funding by late May. Construction would start in June and would be completed by 2012.

The second leg of the Triangle Expressway, could open as early as 2011. The 3.4-mile stretch, the Triangle Parkway, runs from N.C. Highway 147 in Durham to N.C. Highway 540 in Morrisville.

The 12.6-mile Western Wake Freeway, from N.C. 55 near Research Triangle Park to N.C. 55 between Holly Springs and Apex, could open as the third section by 2012.

S.T. Wooten Corp. of Wilson won a bid of $137.4 million for the Triangle Parkway. The Raleigh/Durham Road Builders bid more than $446.4 million for the Western Wake Freeway.