Table presents the performance [present serviceability rating (PSR), which ranges from 0 (poor) to 5 (excellent)] for two different treatments (thin hot-mix asphalt and microsurfacing) each of which was applied to two different pavement sections. Assume that the two pavement sections are similar in all other respects (underlying material type, traffic, climatic conditions, etc.).
|
Year
|
2001
|
2002
|
2003
|
2004
|
2005
|
2006
|
2007
|
2008
|
2009
|
2010
|
2009
|
|
Thin HMA Overlay
|
4
|
3.8
|
3.5
|
3
|
4.45
|
4.25
|
4
|
3.65
|
3
|
2.5
|
2
|
|
Microsurfacing
|
4
|
3.8
|
3.5
|
3
|
3.95
|
3.85
|
3.7
|
3.5
|
3.3
|
3
|
2.5
|
a. Plot a time series trend of the posttreatment performance of each treatment on the same graph.
b. Develop a simple posttreatment performance model for each treatment.
c. Using the posttreatment performance models, determine, for each treatment, the values of the following measures of long-term effectiveness: (i) service life, (ii) increase in average condition, and (iii) area bounded by under the curve. The threshold condition for the treatments is 3.0 PSR. Tabulate your results.
d. Which treatment, in your opinion, is more effective? Explain.
e. The performance models you developed use only the treatment age as the explanatory variable. Which other explanatory variables could have enhanced the models?