the Circumferential Highway is another name for the bypass. To date, since the '50's, only a 2 mile length has been completed.
The problem is the plan is to put it mostly through Hudson. This requires the destruction of a LOT of homes and the filling of wetlands. The EPA recommended that the highway not be completed back in 1993.
The construction that was done, including the rebuilding of the Sagamore Bridge, was enough to unload traffic in the worst areas. US-route 3 was also rebuilt and widened allowing for more capacity.
Litchfield and Hudson have not allowed any more construction along the proposed route of the highway JUST IN CASE the plan is allowed to go forward. The biggest problem with Nashua is there is only 3 bridges over the Merrimack River.
The Manchester airport access road is currently under construction and is expected to be completed by 2010. This is part of the Circumferential Highway plan. It will include access to US -3 and 3A. This should help alleviate some of the problems. local residents will no longer have to travel 7 miles before crossing the river.