Historically, Kentucky has been synonymous with coal. This is because Kentucky produces 160 million tons of coal per year. This translates into relatively heavy volumes of coal-haul truck traffic moving on public highways. Excessive load and tire pressure are common problems in Kentucky. In response to these severe truck traffic conditions, the Kentucky Department of Highways in conjunction with the Kentucky Transportation Center developed an experimental program to evaluate effectiveness of modified asphalt systems that are available in the market. This paper deals with two projects that were designed to study polymer modified asphalts. Polymer modified asphalts are claimed to: (a) reduce thermal cracking, usually associated with low temperatures and (b) reduce rutting, usually associated with high temperatures and heavy loads. Kentucky's unique environment conditions provided the opportunity to test these claims.