ABSTRACT
Transportation asset management plans (TAM Plans) have long been a valuable communication and implementation tool in numerous countries, especially New Zealand, Australia, and the United Kingdom. They were introduced to the United States in the 2011 AASHTO Guide for Transportation Asset Management, and became mandatory under federal law in 2012.
Under the 2015 draft US federal rules, TAM Plans are required to contain a quantitative ten-year network-level analysis of investment plans, life cycle costs, risk, and accountable performance targets. State transportation agencies are required to implement bridge management systems to serve bridge-level planning needs, and to generate the network-level information for publication in the TAM Plan. This is a new process for many agencies, so the rules allow an interim process to give them enough time to improve their capabilities.
Several of the states, specifically Minnesota, Ohio, Nevada, Texas, and Alabama, have been early adopters of TAM Plans but were not yet ready to produce the necessary quantitative network level bridge information. They have elected to develop spreadsheet-based analyses of life cycle cost and the funding vs performance tradeoff, which can serve in this interim role.
The interim analysis uses a summary of current network conditions, a hybrid Markov/Weibull deterioration model, and a model of maintenance and preservation treatments including costs, application rates, and effectiveness. These feed into a life cycle cost analysis of preservation needs and intervals; a computation of preservation return on investment; and a parametric analysis of ten-year deterioration, preservation policies, funding requirements, and performance outcomes. The agencies differ in the performance measures used, the scope of the analysis, policy emphasis, and implementation capabilities. The paper will describe, compare, and contrast the models in the context of each agency’s management needs.
