Conceptual level life-cycle cost analysis algorithm for low volume bridges

The Moving Ahead for Progress in the 21st Century (MAP-21) Act (P.L. 112-141) instituted in 2012 by the Federal Government emphasizes investing public funding to spur growth and development of the nation\u27s transportation infrastructure and as one its goals requires each state to develop a Transportation Asset Management (TAM) plan. The purpose of a TAM plan is to prioritize expenditures of transportation funding in a manner that promotes construction, replacement, and maintenance projects that provides the highest overall network condition. Current prioritization algorithms favor high volume roads and bridges over those with low volumes. Iowa is an agricultural state and as a result has a lot of Farm-to-Market (FM), major and minor collector roads. Much of the rural road network is managed at the county level. Iowa counties have limited ability to fund the needed maintenance and replacement of low volume bridges, making it essential for County Engineers to have a decision tool to properly allocate available funds and execute effective asset management. This research focuses on the development of a simplified Conceptual Life-Cycle Cost Analysis (CLCCA) model that can be used as a decision making tool by county engineers. It focuses on rural low-volume bridges in three counties in Iowa - Boone, Story and Marion - which have an Average Daily Traffic (ADT) of less than 50 vehicles. The research found that the data necessary to populate the classic bridge LCCA model was not available in many cases because the counties simply do not use an accounting system that allows specific minor maintenance and repair costs to be directly associated with specific bridges. The lack of maintenance and repair cost data acts as a barrier to implementing a LCCA-based TAM plan at county-level. Therefore, the proposed model is designed to make maximum use of the available information to the typical Iowa County Engineer and provides a conceptual life-cycle cost. The conceptual life cycle cost thus obtained can be used for making important transportation investment decisions such as in the allocation of funds and to establish an efficient TAM plan at the county level. The research validated the model using a stochastic sensitivity analysis. The results of the sensitivity analysis are presented and show that the most sensitive factor contributing to the final conceptual life cycle cost is the discount rate used in the calculation. The results of the CLCCA vary from a comprehensive LCCA by less than 1 % and are reasonably close to the actual costs. Hence, the thesis recommends that the CLCCA be used in lieu of classic LCCA to make TAM prioritization decisions for low volume bridges in Iowa