Equipment World Digital Magazine
Issue link: http://read.dmtmag.com/i/565622
September 2015 | EquipmentWorld.com 56 better service to taxpayers, with added value well beyond the higher initial cost. Current highway fund- ing contains several directives to both set and monitor pavement performance targets. Not always this way It wasn't always this way. The origi- nal interstate construction build out (1956 to 1991) emphasized con- struction speed, for example. The entire 42,000-mile system was to have been completed in 20 years, so the focus on was productivity, not longevity, and certainly not smoothness as defined today. Deep-section pavements like today's asphalt Perpetual Pavements were not allowed, and the goal was to put down pavement as fast as possible, toward a goal of total system completion by 1975. This whole philosophy reflected that early federal-aid funds were for construction, not state maintenance activities. Maintenance – today the key to sustained high LOS – was to be the complete responsibility of the states. Congress and the Federal Highway Administration even made sure states did not enhance their pavement designs to reduce future maintenance responsibilities. The Intermodal Surface Transpor- tation Efficiency Act of 1991 (ISTEA) called for engineers to take a close look at how they were evaluating paving materials. One particular problem was rut- ting in asphalt. "Rutting became a national epidemic in the 1980s," says Gerry Huber, associate direc- tor of research, Heritage Research Group in Indianapolis. This led to the most important development in hot mix asphalt and pavement design, the shift to performance-graded (PG) liquid as- phalts, as evidenced in Superpave. road science | continued Durable interstate pavement with extended life cycle begins with base stabilized to engineering designs, or value-engineered to save money while providing enhanced longevity. Oregon, 1968: Interstate highways were built for speed of construction, not durability or longevity. Photo: Tom Kuennen Photo: Oregon DOT