The City of Ottawa rehabilitates its road network through its annual road resurfacing program and integrated road-sewer-watermain reconstruction. The treatment strategies can vary from preservation treatments (i.e., crack sealing, microsurfacing, and thin overlays) to resurfacing (i.e., mill and overlay, pulverize and pave) to reconstruction. The City commissioned Stantec Consulting to perform a Pavement Performance Study. One of the study objectives was to carry out a comprehensive review of the performance /effectiveness of the pavement rehabilitation strategies used by the City. The City uses a computerized Pavement Management System (PMS) as an important tool to manage its road network, especially in the development of its Annual Road Resurfacing Program. The PMS is used for core inventory related to City’s entire road network. The system is continually updated with pavement condition data (roughness and surface distress data) collected under an annual program in a manner that condition data for each road is collected on a 3 to 5-year cycle.
Using the information stored in the City’s PMS, Stantec reviewed the information to determine the effectiveness of treatments used by the City for the past two decades. Historical condition and construction history information of the sections was used to evaluate the effectiveness of each treatment. Two different approaches, benefit increase and effectiveness area, were utilized to evaluate the effectiveness of the City’s treatments. The effectiveness of a treatment can be defined as the difference in area between the post-treatment performance curve and the do-nothing curve over time. The “jump” in pavement condition after a maintenance treatment can be called the benefit increase, which is measured in the units of a performance index. Statistical analysis was carried out to compare between different treatments and identify best strategies that can be adopted by the City for future maintenance programs. The treatment effectiveness area approach was further utilized to compare between different types of asphalt mix (Marshall mix vs. Superpave). In addition, it was used to assess the effect of pavement cross section on the pavement performance.