Quantifying the Effects of Climate Change on Pavement Performance Prediction
using AASHTOWare Pavement ME Design
Authors: Chowdhury Md Shahjalal 
Published: September 2020

Climate change is one of the most concerning global issues and has the potential
to influence every aspect of human life. Like different components of society, it
can impose significant adverse impacts on pavement infrastructure. Although several
research efforts have focused on studying the effects of climate change on natural
and built systems, its impact on pavement performance has not been studied as
extensively. The primary objectives of this thesis research was to quantify the
effect of temperature changes on flexible pavement response and performance
prediction using the AASHTOWare Pavement ME Design (PMED), and quantify the effects
of Local Calibration Factors (LCFs) used by different state highway agencies in the
United States on predicted pavement performance. Particular emphasis was given to LCF
values used by the Idaho Transportation Department. The climatic data, as well as LCFs
corresponding to several different states, were used to identify how different LCF
values affect pavement performance prediction. The effects of atmospheric temperature
changes on pavement temperature and Asphalt Concrete (AC) layer modulus were studied
by analyzing the intermediate files generated by PMED. Finally, the impact of temperature
change on AC dynamic modulus (E*) was also analyzed to link the PMED-predicted distresses
with asphalt mix properties.

Historical climatic data was obtained from the Modern-Era Retrospective Analysis for
Research and Applications (MERRA) database. Projected data considered to simulate the
temperature changes in the future were generated by adopting two different approaches:
(1) Manual alteration of historical temperature distribution data to represent scenarios
with increased mean and standard deviation values; and (2) Use of temperature data
projected by established Global Climate Models (GCM). All different climatic scenarios
were used in PMED along with a standard pavement section, and the distresses predicted
over the design life of the pavement were compared. Simulation results showed consistent
increase in Total Pavement rutting and AC rutting with increasing air temperatures. The
effect of temperature increase on AC thermal cracking predicted by PMED demonstrated
inconsistent trends. In contrast, the projected temperature increase had no significant
effect on bottom-up fatigue cracking for the chosen study locations. It was found that
the impact of changed air temperatures can be different for pavement sections constructed
in different geographic locations. Moreover, the analysis confirmed that the Local
Calibration Factors (LCFs) established by different state highway agencies played a
major role in governing the effect of future temperature increase on predicted pavement
performance. Through an extensive study of the LCFs used in the states of Idaho, Colorado,
and Michigan, it was observed that the LCFs in Idaho did not adequately reflect the effects
of future temperature changes on predicted pavement performance. Findings from this study
emphasize the importance of considering non-stationary climate conditions likely to occur
in the future during the process of pavement design. Moreover, this study also highlighted
different aspects of the LCFs that play a significant role in capturing the effects of
climatic factors on pavement performance predicted by PMED. Based on the findings, it is
believed that further fine-tuning of the LCFs used in Idaho may be needed.