That pounding noise you've been hearing in your head could be a remnant of too much holiday cheer — or it could be the sound of construction crews pounding pilings into place at the construction site of the south Medford interchange.

That pounding noise you've been hearing in your head could be a remnant of too much holiday cheer — or it could be the sound of construction crews pounding pilings into place at the construction site of the south Medford interchange.

The Interstate 5 interchange, scheduled for completion in spring 2010, will replace the existing interchange at Barnett Road at an estimated cost of $70 million. The overpass will connect the freeway with Highland Road at Barnett on the east side of the freeway and with Garfield Street on the west side.

This week, work crews with Wildish Standard Paving have been setting up and pounding in 67 steel pilings, each 40 feet long, which will serve as the underpinnings of the main overpass above I-5.

Work on securing those pilings on the freeway's west side is expected to be completed by Wednesday, according to Gary Leaming, project information specialist for the Oregon Department of Transportation. Another 67 beams have already been driven into place on the east side.

Once the pilings are in place, the crews will create a concrete base on which the overpass I-beams will rest. They expect to begin placing the giant beams that will form the base of the overpass across the freeway in late spring of 2008.

Leaming said work on the project is ahead of schedule and could be completed in 2009. Work is expected to slow during the winter months, with the focus on construction of the overpass structure. Current phases under construction include the northbound off-ramp and southbound on-ramp.