Susan Louise Tighe

Incorporating Road Safety into Pavement Management

Improving road safety through proper pavement engineering and maintenance should be one of the major objectives of pavement management systems. When pavements are evaluated in terms of safety, a number of factors related to pavement engineering properties are raised, such as pavement geometric design, paving materials and mix design, pavement surface properties, shoulder type, and pavement color and visibility. Each year there are voluminous annual reports on traffic accident statistics and discussions of such road safety issues as road safety modeling and pavement safety measurements and criteria. Although road safety may be considered a separate area, it should be incorporated into pavement management systems. The main pavement engineering relationships associated with road safety are identified, and the various aspects of road safety related to pavement management, such as pavement types, pavement surface macrotexture and microtexture, and pavement safety measurements, criteria, and evaluation methods, are discussed. A systematic approach is proposed for the coordination of pavement maintenance programs with road safety improvement and the incorporation or integration of safety management with pavement and other management systems. Finally, a list of possible remedial measures for road safety improvements associated with pavement maintenance activities is recommended.

Guidelines for Probabilistic Pavement Life Cycle Cost Analysis

To select the most appropriate pavement design for a given situation, it is necessary to understand how the pavement properties and in-service conditions relate to performance and life cycle cost. A given design may be most appropriate on one type of road and least appropriate on another type of road. This design selection is further complicated by the advent of new design methodologies, materials, and construction delivery techniques. Life cycle economic analysis is an important tool for comparing alternative treatment strategies. A life cycle analysis can use a deterministic approach, which incorporates a single point value, or it can use a probabilistic approach, which includes a mean, variance, and probability distribution. The probabilistic approach is better suited to describing the uncertainty associated with engineering. The Canadian Strategic Highway Research Program Canadian Long-Term Pavement Performance database and data provided by the Ministry of Transportation of Ontario were used in this analysis. Most construction variables are generally believed to be best described by a normal distribution. However, a lognormal probability distribution is better suited to describing these variables. This best fit is based on both a mathematical examination and a comparison of similar variables such as stocks and real estate values. It is also shown that thickness is a probabilistic variable that should be combined with the cost and incorporated into pavement life cycle costing. Ignoring the lognormal nature of these variables introduces bias into a life cycle cost analysis and does not reflect the true overall cost.

State-of-the-art report on use of nano-materials in concrete

Nanotechnology application to concrete presents an innovative approach to improve concrete properties based on the ability to manipulate the cementitious material at an atomic scale. This paper presents a review of the nano-materials that have been used in concrete. The literature survey revealed that four nano-materials are most often used to modify concrete properties; these include nano-silica (nano-SiO2), nano-titanium dioxide (nano-TiO2), carbon nano-tubes (CNTs) and carbon nano-fibres (CNFs). All of these four nano-materials have shown improvement in many concrete properties. Both nano-TiO2 and nano-SiO2 reduce bleeding and segregation, and improve mechanical and transport properties. CNFs and CNTs tend to adversely affect the fresh properties due to agglomerations, which are overcome when a surfactant or ultrasonic mixer is used. However, both CNFs and CNTs significantly improve the mechanical properties of concrete. This paper also discusses how concrete durability is improved when nano-materials are added to concrete. In addition, this paper identifies several research needs based on the gaps in the current state of knowledge on using nano-materials in concrete.

Pervious Concrete Pavement: Integrated Laboratory and Field Study

Pervious concrete pavement is an environmentally friendly, sustainable paving material for low-volume, low-speed applications. Pervious concrete has been used in warm climates extensively, but its use in freeze–thaw climates has been limited. The Centre for Pavement and Transportation Technology at the University of Waterloo and the Cement Association of Canada, Portland Cement Association, and local Canadian ready-mix producers have partnered to carry out a Canada-wide study to evaluate the performance of pervious concrete. Three test sections have been constructed to date with more planned for the future. The current test sections are located in southern Ontario and southern British Columbia. They are designed to represent all aspects of pervious concrete including but not limited to materials, design mixtures, structural design, potential applications, fresh and cured properties, permeability, environmental strain, filtration capabilities, and maintenance needs and options. A surface distress evaluation form has been developed with information gathered from two of the test areas as well as a literature review. Two test areas have experienced a winter season and showed minimal surface distresses and maintained permeability. Permeability testing is carried out regularly to track changes as well as to evaluate effects of winter maintenance. Instrumentation has been installed at the test areas to track moisture movement throughout the structure, strain caused by environmental conditions, and the filtering capabilities of pervious concrete. The results of this project will be instrumental in understanding the performance and behavior of pervious concrete in the Canadian climate.

Analytic Hierarchy Process as a Tool for Infrastructure Management

The role of infrastructure management has been continuously changing since the late 1980s. Public agencies have started to incorporate private-sector practices. These new practices include the use of customer inputs to develop new goals and policies, development of new evaluation procedures for priority programming optimization, and addition of feedback loops into infrastructure management systems. One of the new evaluation procedures adopted into infrastructure management is the analytic hierarchy process (AHP). AHP is a decision-making tool that incorporates both qualitative and quantitative factors. AHP has increased in use and popularity because of its ability to reflect the way people think and make decisions by simplifying a complex decision into a series of one-on-one comparisons. The results are then synthesized and presented as a percentage of all the options evaluated. This presentation will illustrate AHP with two examples. In the first example, AHP was used to compare fast-track concrete repai...

Allocation of Pavement Damage Due to Trucks Using a Marginal Cost Method

A procedure was developed for quantifying the pavement cost of proposed changes in regulations governing truck weights and dimensions, particularly the marginal cost method used for pavement cost allocation. The procedure was part of a comprehensive study undertaken by the Ontario Ministry of Transportation in response to government and industry initiatives to harmonize Ontario’s truck regulations with those in surrounding jurisdictions. The marginal pavement cost of truck damage was defined as a unit cost of providing pavement structure for one additional passage of a unit truckload (expressed as equivalent single axle load). The results indicate that the highway type (or truck volumes associated with the highway type) has a major influence on marginal costs. For example, the annualized pavement life-cycle cost of the passage of one additional typical truck on 1 km of a highway in southern Ontario can range from about

Evaluation of Semiautomated and Automated Pavement Distress Collection for Network-Level Pavement Management

0.004 for a freeway to

DEVELOPMENT OF PREVENTIVE MAINTENANCE DECISION TREES BASED ON COST-EFFECTIVENESS ANALYSIS: AN ONTARIO CASE STUDY

0.46 for a local road (Canadian dollars). The marginal cost method can be used to quantify pavement damage due to any axle load combination for both new and existing, in-service pavements. The knowledge of marginal costs would enable highway agencies to quantify the impact of specific regulatory changes of truck axle weights on pavement costs; for example, to quantify the pavement costs associated with increasing allowable truck weights of logging trucks on a specific segment of the highway network.

Atomic force microscopy to investigate asphalt binders : a state-of-the-art review

The Ministry of Transportation Ontario (MTO) and the University of Waterloo examined the feasibility of using automated pavement distress collection techniques in addition to data collected through manual surveys. Test sections including surface-treated, asphalt concrete, composite, and portland cement concrete pavement structures in 37 locations in southern Ontario, Canada, were evaluated. Distress manifestation index (DMI) values were computed for each section by MTO pavement design and evaluation officers using the manual evaluation data collected. DMI values were then computed for each section by using automated distress evaluation data. Before DMI values could be computed, the relevant data had to be extracted and verified, and the distress data had to be categorized. DMI values computed from data collected manually and by using automated systems were compared. Finally, a repeatability analysis was performed on both the manual and the automated techniques. Results indicate no significant differences among sensor-based equipment; however, there are significant differences among measurements obtained from digital image-based technology. The implications of such outcomes are discussed, including the specifics regarding methodology implementation in order to encourage practitioners to benefit from the preliminary investigation. Current available techniques can provide MTO with valuable information for pavement management purposes. The automated results are comparable with manual surveys. However, these surveys should be supplemented with manual surveys, especially for design purposes, because some of the pavement distresses were difficult to identify with the automated methods.

Towards the classification of recycled concrete aggregates: influence of fundamental aggregate properties on recycled concrete performance

Various transportation agencies have begun to consider implementing preventive maintenance (PM) strategies as part of their regular pavement management programs. To determine whether a PM strategy is more cost-effective than a conventional maintenance strategy, various technical and economic analyses were carried out. Currently, most agencies have limited information on the cost-effectiveness (CE) and long-term performance of PM strategies, so it is difficult to determine when and where these treatments should be used. The use of PM treatments based on a CE calculation and analysis is examined, and a decision tree (including treatments and strategies) is developed for each functional pavement class of the Ontario road network. Pavement data from the Ministry of Transportation of Ontario are used to perform a CE calculation for each suggested PM treatment and strategy. On the basis of a comparison and analysis of CE calculation results, guidance is provided on the right treatment, time, and strategy cost level for each functional pavement PM program within the Ontario environment. The results are summarized in the form of a decision tree.