Although LCCA has provided real benefits to PennDOT, implementation was not without challenges.
LCCA Data Inputs. PennDOT has relied on both expert opinion and historical data to develop LCCA inputs. PennDOT recognized its lack of systematic data as a potential implementation roadblock, and specifically decided to use documented expert opinion before it had a source of properly analyzed historical data. At the same time, existing databases were investigated for their ability to supply these inputs. By developing the process at the same time as data sources, PennDOT was able to implement its LCCA program much earlier than it would have if the process and inputs had been developed sequentially.
|To quantify work zone user costs, including user time values, PennDOT uses a methodology derived from National Cooperative Highway Research Program Report 133, "Procedures for Estimating Highway User Costs, Air Pollution, and Noise Effects."|
User Costs. PennDOT recognizes that including work zone user costs in its pavement selection process is an extension of its interest in normal operations levels of service. As consideration of user costs is an integral part of the department's statewide planning process, PennDOT decided that user costs should be applied to the project-level decision process as well. The methodology that PennDOT uses to quantify work zone user costs, including user time values, is derived from National Cooperative Highway Research Program Report 133, "Procedures for Estimating Highway User Costs, Air Pollution, and Noise Effects."
Uncertainty. Recognizing that LCCA inputs are uncertain, PennDOT has modified its pavement selection criteria accordingly. PennDOT makes pavement design decisions based upon the information supplied by its LCCA process. However, LCCA inputs, such as agency costs and pavement performance, cannot be predicted with complete certainty. Consequently, when the total agency costs of different alternatives are similar, other factors are specifically included in the decision process. PennDOT believes that the "10 percent rule" accounts for uncertainty in LCCA inputs and allows engineering judgment to be incorporated into the pavement design selection decision.
Industry Relationships. PennDOT has reached out to the State's paving industry groups in order to improve their understanding of PennDOT's selection process. Making the pavement-type selection process transparent has enhanced the credibility of the process and has turned potential adversaries into allies.