摘要: |
Since the inception of its pavement management system in the early 1990’s, the Michigan DOT has been using the Distress
Index (DI) as a measure of surface condition for pavements. The DI is based on an assignment of increasing-value numeric
“points” to specific distress type-and-severity observations obtained through detailed surveys; the more detrimental a distress
type/severity observation is to pavement structural condition, the higher the assigned point value. The distress information is
collected via digital images by vendors on roughly half the MDOT network every year. There appears to be a gap between what
the state of the practice in the pavement data collection industry typically provides nationwide, and the complexity of the distress
information MDOT asks for. MDOT has decided to suspend the collection of the full extent of the distresses typically requested,
and to suspend the use of DI as the pavement condition measure. This research is expected to investigate and recommend a
new condition measure, or revisions to the existing DI system, that MDOT can utilize moving forward. This new/revised measure
is expected to be compatible with what the pavement data collection industry can deliver in an accurate and timely manner. It is
also expected to have low impact on MDOT’s business practices and processes, including the remaining service life (RSL)
estimation process and the life-cycle cost analysis (LCCA) process.
MDOT’s Pavement Management Section oversees the Department’s implementation of the state life-cycle law. MDOT currently
uses a logistic growth curve fit through historic DI data to estimate when a pavement or fix type will reach a remaining service life
of zero. This initial life estimate produces a fix life estimate that is utilized in the RSL estimation process for network-level
pavement condition monitoring. When life-extension benefits of preventive maintenance cycles are added in, the resulting
estimation is a service life value that is used as the analysis period for LCCA calculations. The intent of the LCCA process is to
pick the most economical pavement type for a given planned project location. RSL estimate values are used at the project level
to assist with project type selection and at the network level to forecast network condition. Therefore, an accurate performance
prediction/estimation methodology is critical to the LCCA, project planning, and budgetary decision-making processes for the
effective use of transportation funding.
Because the logistic growth curve was chosen several decades ago, MDOT feels it is time to re-evaluate whether or not the
logistic growth curve is still the best method for predicting performance of individual projects and the various fix types (as a
group). This research would evaluate and recommend improvements to the data modeling methodology by comparing the
logistic growth curve to other pavement performance modeling methods that are being utilized across the country to determine
the best choice for management of Michigan’s pavements. The model will, of course, utilize the new pavement condition
parameter adopted by MDOT from the first part of this research project.
This investigation would also look at ways to incorporate modeling of network level International Roughness Index (IRI), rutting, faulting, and cracking. This would assist with Michigan’s implementation of the new federal pavement
performance rules which require each state to set targets for pavement condition based on a composite measure incorporating
three of four condition metrics: IRI, cracking percent, and rutting-or-faulting. |