At a crowded public meeting in Dunwoody on Tuesday, state road officials revealed new renderings and information about the revamp of the SR 400/I-285 interchange. The project aims to keep the 400,000 cars that pass through the junction every day moving by adding flyover bridges, access roads and more width to existing bridges. The finished product isn't quite as knotted up as the infamous Spaghetti Junction, but it's close. Four levels of flyovers (Spaghetti Junction has five) will twist over and under one another, and barrier-separated collector-distributor (CD) lanes will be built along both highways. "Braided" ramps will be constructed around Ashford Dunwoody and Roswell roads, and about two miles of improvements would take place between the Glenridge Connector North to Hammond Drive. GDOT's website has detailed maps and documents specifying each change.

The interchange improvements, when combined with the Georgia-400 CD lanes project, will leave the state with a bill for around $1.056 billion. Yeah, with a "B." It will be the priciest roadwork in Georgia history. In May, the State Transit Board voted to free up $130 million in bonds and allow the use of $81.5 million in state motor fuel funds. That windfall bumped the start of the project up by three years, to 2016. Before then, GDOT needs to buy about 80 parcels of land (many of which are occupied), complete the engineering studies and meet environmental regulations. They say it'll be complete by 2019. In the meantime, prepare for traffic nightmares like you have never seen. It's only three years, y'all.

· I-285 and SR 400 Improvements [GDOT]

· Big plans for Ga. 400/I-285 interchange just got bigger [AJC - Subscriber content]