The Circle Track at the General Motors Milford Proving Ground is truly one of a kind. Forming a 4.5-mile circle, the track is a concrete parabolic curve that simulates driving straight indefinitely at varying speeds. The track is made up of 5 driving lanes, with the top lane being the steepest for test speeds in excess of 100 mph. The track was originally constructed in the 1960s and held up well due to a progressive design and sound construction. After 50 years, the joints on the track were worn due to weathering, which signaled the need to rebuild. The redesign included the following:
- Removal and replacement of the bottom four lanes with 8” of new concrete.
- Repairs were made to the top lane, and the interior shoulder was removed and replaced with hot-mix asphalt.
- The entrance was milled and paved, and drainage improvements were made, including adding an edge drain around the entire track.
- Along the outer perimeter, the track received a chip seal and a fog seal to prevent water from getting under the pavement and causing future damage.
Sustainable design considerations included crushing old material into different gradations for future reuse as a base material for roads and slope stabilization.