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Publication Number: FHWA-SA-98-021
Date: April 1998
When the Pennsylvania Department of Transportation (DOT) began planning the rehabilitation of U.S. Route 22 between Easton and Allentown, it faced a huge challenge. The four-lane highway carries lots of traffic–approximately 85,000 vehicles per day–and has several blind corners that make it hard for drivers to see if traffic ahead has slowed down or stopped. This increases the chances of rear-end collisions, which account for more than one-third of all accidents in work zones in the State, according to Pennsylvania DOT. In fact, during a major reconstruction project on Route 22 in the late 1970s, a truck rounded a blind corner and slammed into a group of vehicles stopped in the work zone, seriously injuring several people.
Just halfway through its 20-year life, the long-term pavement performance (LTPP) program is already well on its way to accomplishing a key objective–the development of improved design procedures for new and reconstructed asphalt and portland cement concrete pavements. Data from the LTPP studies have been used to prepare guidelines that will help highway agency staff design better-performing asphalt and portland cement concrete pavements, more accurately predict pavement performance, and gear up for the shift from today's empirical design procedures to advanced mechanistic design procedures.
The second phase of the Federal Highway Administration's (FHWA) Superpave models project is now under way. The project, which is being conducted by the University of Maryland (UM) and a team of subcontractors, is part of FHWA's multiyear plan for developing a system for predicting the performance of asphalt mixes designed using the Superpave system.
The first Superpave parking lot in Phoenix was constructed in 1996. The owner of Liberty Buick asked United Metro Materials, which had already designed mixes for several Superpave pavements in the area, to come up with an improved overlay for the dealership's asphalt parking lot, which was rife with low-temperature cracking. The overlay not only had to be resistant to cracking, but it also had to be relatively thin so that it would be even with the lot's existing ramps and curb cuts. In addition, the overlay had to be economical and look good.
Investing in new technology always raises a question: Will the benefits of the technology justify its costs? To find out the answer for road weather information systems (RWIS), the Pennsylvania Department of Transportation (DOT) tracked the installation costs and the resultant savings in labor, materials, and equipment for one RWIS station along a section of Interstate highway. The highway agency learned that over two winters, the RWIS station saved the State more than $57,000.
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