Risk Assessment of Rollover and Skidding due to Pavement Roughness and Differential Settlement for Enhancing Transportation Safety

In this paper, a closed-loop simulation of vehicle dynamics in CarSim is utilized as surrogate measures to study the effect of pavement roughness and differential settlement on risk of vehicle rollover and skidding. It is found that the influence of pavement roughness on vehicle rollover is significant and the influence of pavement roughness on vehicle skidding is insignificant. The influence of pavement roughness of grade A and B on safety margin of vehicle rollover can be negligible. Pavement roughness of grade C and D significantly reduces the safety margin of vehicle rollover. A 5 cm settlement difference on pavement reduces the safety margin of vehicle skidding on a good road. When the settlement difference is 5 cm, the vehicle rollover and skidding are greatly affected by the lane-changing speed. It provides an effective and general method based on vehicle dynamics for studying transportation safety as well as for setting up criteria for pavement maintenance.

Investigation of flexible pavement maintenance patching factors using a finite element model

Patching of flexible pavements is one of the most important functions of pavement maintenance. Although finite element modeling has become commonplace in the world of pavement engineering, modeling has not yet been significantly leveraged for maintenance applications which improve safety, ride quality, and pavement service life. The objective of this study was to model viscoelastic properties of pavement and patching materials to determine the effect of various repair factors on pavement performance using the finite element method. Specifically, surface permanent deformation, local shear stress concentration, and horizontal strain distribution were investigated. Two types of models were simulated; the first model applied static loading to a surface layer fixed on a plate and the second model applied cyclic traffic loading to a two-layered flexible pavement system. The results demonstrate the importance of patching using a semi-permanent method. The results also demonstrated the accumulated effect of repeated loading using a time-dependent material response. Results also indicated that a larger patching area resulted in less influence of the shape of the area, while a circular area proved superior to a conventional rectangular patch for sizes near the tire footprint and smaller than it. Different responses were observed depending on the type of patching material modeled, demonstrating the effect of material choice in maintenance applications. Finally, mesh optimization was performed to ensure appropriate mesh sizes are used in future studies to accurately represent the pavement layers and patches.

Pavement Maintenance Decision Making Based on Optimization Models

Pavement maintenance prioritization considering both quality and cost is an important decision-making problem. In this paper, the actual pavement condition index of city roads was calculated using municipal patrol data. A linear optimization model that maximized maintenance quality with limited maintenance costs and a multi-objective optimization model that maximized maintenance quality while minimizing maintenance costs were developed based on the pavement condition index. These models were subsequently employed in making decisions for actual pavement maintenance using sequential quadratic programming and a genetic algorithm. The results showed that the proposed decision-making models could effectively address actual pavement maintenance issues. Additionally, the results of the single-objective linear optimization model verified that the multiobjective optimization model was accurate. Thus, they could provide optimal pavement maintenance schemes for roads according to actual pavement conditions. The reliability of the models was investigated by analyzing their assumptions and validating their optimization results. Furthermore, their applicability in pavement operation-related decision making and preventive maintenance for roads of different grades was confirmed.

ANALYSIS ON OPTIMIZATION DECISION OF PAVEMENT MAINTENANCE MODE BASED ON ANALYTIC HIERARCHY PROCESS

With the rapid development of China's transportation and the improvement of people's living standards, China's highways have entered the peak maintenance period. According to the old road conditions and financial conditions, how to choose the appropriate maintenance technology to meet the technical and economic requirements of highway maintenance and construction projects has become a difficult problem faced by highway maintenance management departments. Therefore, based on the principle of index selection, this study comprehensively considered the impact of various factors on maintenance decision-making, determined four evaluation indexes, and systematically studied the compre-hensive decision-making system of asphalt pavement recycling maintenance. Based on the subjective-objective linkage and probability statistics method, the eigenvalue of the applicability of recycling mode was transformed to the same scale of 0 to 100, and the fuzzy scoring interval of the four bids was proposed. The calculation method of pavement quality recovery index (PQRI) and the analysis basis of economic benefits were clarified. Finally, the weight of each index was calculated by analytic hierarchy process, and the multi-index comprehensive decision-making method of pavement maintenance is constructed and used to theoretically verify and guide the actual road section. Results demonstrate that the proposed PQRI can realize the operability of quantifying the later operation of pavement. The weight of each index from big to small is PQRI > economic benefit > applicability of recycling mode. The recycled pavement quality recovery indices and applicability of the four recycling modes have small differences, and the proposed four bids interval makes the decision-making evaluation process more simple and explicit. The decision evaluation results of actual road section verify the rationality and practicability of the decision method. The conclusions are important for the maintenance and management of asphalt pavement recycling technology. Keywords: road engineering, recycling maintenance, intelligent decision-making, fuzzy evaluation