maintenance costs, although this approach was, technically, not a “full” repair. This repair approach allowed the department to direct funds to other assets and needs, while accomplishing an acceptable level of risk reduction for a problematic asset. Closure An owner with many assets in its inventory could forever be replacing “siding with paint and the roof structure with tiles” if he/she doesn’t start making investments before things get bad. Getting back to risk, a challenge is recognizing the likelihood that things will get bad during the next period of time and what may be the consequence if they do. The best way to represent these conditions is via a deteri- oration model, which, in most instances, curves downwards with respect to time. We can understand the model by intuition, but there are other reasons for it, as well. For assets such as retained slopes or retaining walls instead of pavements and bridge decks, the parameters of this deterioration curve, or perhaps family of curves, are not well known. The parameters will become well known with time, as systems such as the one in Colorado described above are implemented and observat ions of conditions are made through multiple years. Until then, we need to use judgment, something with which geotechnical engineers are very familiar. Mark Vessely, P.E., is a vice president for Shannon & Wilson in Denver, Colo., and works with transportation departments on projects related to risk-based asset management; mitigation for landslides, rockfall, and other geologic hazards; and highway corridor improvement projects. He is the principal investigator (PI) for a National Cooperative Highway Research Program (NCHRP) project to develop a Geotechnical Asset Management (GAM) implementation manual for state departments of transportation. Scott Anderson, Ph.D., P.E., is a principal engineer for BGC Engineering in Golden, Colo., a member of DFI, and co-chair of the Transportation Research Board’s Joint Section Subcommittee on GAM. He was the manager of the geotechnical engineering team within the Federal Highway Administration’s Resource Center. Through these roles, Anderson provided national leadership on GAM for highways, and he contributed to the scoping and selection of the NCHRP project for which Vessely is the PI. DEEP FOUNDATIONS • JAN/FEB 2018 • 73
