Browsing by Author "Haas, Ralph"

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    Measures of Pavement Performance Must Consider the Road User
    Hudson, W. Ronald; Haas, Ralph; Perrone, Eric (2015-06-04)
    In 1960, Bill Carey and Paul Irick developed the Present Serviceability Index (PSI) as a user-based performance measure to define pavement quality and failure at the AASHO Road Test, a controlled load experiment that cost $300 million in 2014 dollars (1). The Canadians used the same approach in creating their Riding Comfort Index, but on a 0 to 10 scale. The PSI method was adopted and used worldwide to define pavement quality until the early 1990's when FHWA arbitrarily adopted International Roughness Index (IRI). It was intended as a measure of quality for HPMS (Highway Performance Monitoring System) data because IRI was touted to be standard and universal by the World Bank. PSI is still used by many agencies around the world but most state DOTs felt forced to follow FHWA and adopt IRI. The IRI is not standard state-to-state and more importantly the levels of "acceptability" and "failure," which must be set to define performance, vary from state-to-state. The US Federal MAP-21 requires state DOTs to do broader "performance" management and develop acceptable pavement performance measures (2). PSI is tied to road user response but IRI is not. This paper examines these indexes and how they derived. It contends that PSI can serve all levels of need while IRI does not, because it is not understood by highway users and legislators. PSI reflects human rider response and IRI does not close that gap.
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    Quantifying the Benefits of Good Pavement Asset Management
    Hudson, W. Ronald; Haas, Ralph (2015-06-04)
    In the 1970s it became clear that pavements could not actually be designed for 30-50 year life; and that they had to be managed. It was found necessary to consider construction, maintenance, rehabilitation, and even reconstruction in the life of pavements, not just a design. The concept of pavement management was thus born. The authors have jointly about 8 decades of experience in pavement management, and, with others have seen many agencies and engineers realize the qualitative benefits of pavement management. As a result some states, provinces, counties, and cities have adopted PMS but many others have been reticent because we could not quantitatively show them the benefits of changing the way they do business. Defining benefit is required for pavement and asset management. Otherwise, agencies can feel they are doing a good job because they had done it that way for many years. In the last few years enough research and data collection have been done on active PMS programs to quantify the benefits of pavement management systems and to be able to calculate the benefit/cost ratios and/or the return on investments. In turn, this enables agencies to save large sums of public funds by adopting pavement management. This paper presents the results of 20 years of evaluations of PMS in several active agencies. It shows the benefit/cost ratios to range from $5 to $20 million for each $1 million spent on the pavement management process in their agency.