Source: Untar Public Relations – VC
Johanson Pardede officially earned a Doctorate in Civil Engineering after successfully defending his dissertation during an Open Doctoral Promotion Examination held at the Auditorium of Untar Campus I on Thursday (23/10/2025). With this achievement, he became the 99th Doctor of Civil Engineering from Untar’s Doctoral Program in Civil Engineering and graduated with a Highly Satisfactory distinction.
In his dissertation entitled “A Model for Improving Soft Soil Pavement Stability on the Palembang–Betung–Jambi Toll Road Section,” Dr. Johanson highlighted the crucial role of toll road infrastructure in driving economic growth, enhancing productivity, and strengthening regional connectivity. However, he emphasized that toll road development in Sumatra faces significant challenges due to the prevalence of soft and peat soils. Through his research, he explored solutions to address stability issues associated with these soil conditions to improve the performance and longevity of toll road infrastructure.
The study revealed that Section B of the toll road had a moderate condition, reflected by a Pavement Condition Index (PCI) score of 54. Soft soil was identified as the primary factor contributing to pavement deterioration, further aggravated by vehicle loads reaching up to 2.5 times the standard limit. As an innovative solution, Dr. Johanson proposed the use of stone crusher aggregate waste as an 11-centimeter capping layer, which demonstrated a California Bearing Ratio (CBR) value of 68.1 percent while also offering cost efficiency. The implementation of the study focuses on strengthening road structures from the subgrade level, particularly in soft soil areas, as well as enforcing vehicle load restrictions along the Palembang–Betung–Jambi Toll Road.
“This innovation transforms industrial waste into a sustainable construction solution capable of extending the service life of toll roads to up to 40 years while reducing costs,” Dr. Johanson explained during his presentation.
The examination was chaired by Untar Rector and Examination Chair Prof. Dr. Amad Sudiro, S.H., M.H., M.Kn., M.M., with Dean of the Faculty of Engineering Ir. Harto Tanujaya serving as Chair of the Board of Examiners. The Main Promoter was Prof. Ir. Leksmono Suryo Putranto, M.T., Ph.D., accompanied by Co-Promoter Prof. Ridho Bayuaji, S.T., M.T., Ph.D. The examination panel also included Internal Examiner Ir. Oei Fuk Jin, S.T., M.Eng., D.Eng., and External Examiner Dr. Florentina Pungky Pramesti, S.T., M.T.
With the successful completion of his doctoral defense, Dr. Johanson’s research is expected to serve as an important reference for toll road infrastructure development in Indonesia, particularly in regions characterized by soft soil conditions, while contributing to the advancement of sustainable civil engineering practices in the future. (VC/YS)