Billings grew fast once the Northern Pacific Railroad arrived in 1882, expanding across river terraces and weathered sandstone mesas. That rapid spread left a patchwork of fill materials and native clay subgrades under today's roads and parking areas. A flexible pavement design here has to reconcile heavy truck traffic on I-90 feeders with freeze-thaw cycles that stress the layer interfaces. The engineering team analyzes subgrade stiffness, drainage patterns, and projected ESAL loads to build a section that resists rutting and fatigue cracking over a 20-year design life. For commercial pads where soil conditions vary sharply across the lot, we often combine the pavement analysis with plate load test data to calibrate the modulus of subgrade reaction directly beneath the asphalt section.
A Billings pavement section lives or dies by its base drainage—skip the daylighted aggregate layer and you will be patching cracks by the second winter.
