(Gold Award) Circle Test Track Reconstruction at GM’s Milford Proving Ground, Mich.
Contractor: Ajax Paving Industries, Inc.
Owner: General Motors
Engineer: PEA, Inc.
In 1924, General Motors (GM) original Milford Proving Grounds (MPG) started with only 1,125 acres of land with 7 miles of tests roads.
In November 1963, the MPG opened a Circle Test Track, which had an expected service life of 30 to 50 years. By 1964 the grounds grew to 4,011 acres of land with 73 miles of roads that included the test track. Today the track is busiest and most important test track at MPG. It is used for both development and durability testing of approximately 900 vehicles per year, during which time an estimated 1.5 million miles are test driven.
The original track consists of an upper concrete shoulder, five concrete driving lanes posted for speeds up to 100 mph, and inner asphalt shoulders. The upper driving lane has a 30 percent bank angle. The parabolic banking track measures about 4.5 miles long. MPG lays claim to the only concrete circle parabolic test track.
A reconstruction project performed by Ajax Paving Industries, Inc.* included: patching of lane 5; removal and replacement of four concrete driving lanes and an inner asphalt shoulder, milling and replacement of asphalt ramps to the test track, resealing existing joints in upper shoulder and lane 5; installation of edge drain outside of the inner shoulder; subgrade improvements; and improved signing, electrical and striping
The 8 in. thick pavement design included the latest Michigan DOT special provisions for high performance concrete and quality control for concrete. GM required a dolomite aggregate used in the original mix to be used in new high performance mix. The transverse and longitudinal joints were modified to be coated with an enhanced epoxy. GM used the original 20 ft transverse contraction joint spacing, however the design required four transverse expansion joints to be placed at equal distance around the track.
The latest technology was also incorporated into the means and methods of paving. Numerous hours were spent with and by the paving equipment manufacturer to make modifications to paving equipment to ensure concrete placement with automated grade control to the correct vertically location and horizontal grade, but also to achieve the best possible ride measurement.
GM required ride quality measurement of the new pavement surface. Based on the actual field MRI measurements and the “seat of your pants” ride measured by GM test drivers at speeds in excess of 150 mph, the newly placed pavement only required corrective action at one location in one lane of 18 lane miles of paving. Reopening just short of the 53rd anniversary of the original opening date, the reconstructed track will continue to serve GM’s world-class automotive proving grounds.
* ACPA Member.