Hernán de Solminihac

Proposal of an Integrated Index for Prioritization of Bridge Maintenance

The bridge rating used in bridge management systems commonly uses only a structural condition. Factors such as seismic risk, hydraulic vulnerability, and strategic importance are commonly used in an isolated fashion. However, these factors are relevant when there is no possibility to calibrate deterioration models. This research uses the needs-based framework for developing an integrated bridge index (IBI) as an aid for prioritization and decisions made on maintenance and rehabilitation of bridges. The index weighs the structure distresses, hydraulic vulnerability, seismic risk, and strategic importance of the bridge. The index was calibrated using visual inspection, survey to experts, and regression analysis. After, the index was applied on six bridges placed on a primary road of Chile. To organize visual inspection, bridge inventory, and compute IBI and rank bridges, a software was developed. The calibration of the IBI index shows a correlation of 98% and all the parameters obtained were significant. Further research is needed to integrate cost with the proposed index and allocate maintenance activities.

Development and Validation of a Method to Evaluate Unpaved Road Condition with Objective Distress Measures

The condition of unpaved roads is commonly assessed by using qualitative distress measures. Some methods do not consistently consider the relative effect of multiple defects on road condition, or their application is limited to the conditions under which they were developed. In 2007, the Ministerio de Obras Públicas of Chile and a private consultant developed the Modelos de Deterioro de Caminos No Pavimentados study. The scope of the study was to gain experience with and understanding of unpaved road behavior. The main goal of the study was to develop and validate a method for evaluating unpaved road condition by using objective measures of distress, drainage, and profile characteristics. The scope was to design a versatile tool that was applicable to any location, followed a simple procedure, and used cost-effective survey techniques. The proposed approach is to define condition models from a questionnaire administered to a professional panel by applying the Delphi method. As a result of the study, equations representing the unpaved condition index (UPCI) and condition limits were developed for unbound gravel, stabilized gravel, and earth roads subject to three climates: dry, Mediterranean, and humid. UPCI equations and condition limits were validated successfully; the method to assess unpaved road conditions was reliable and versatile.

Calibration of Performance Models for Surface Treatment to Chilean Conditions The HDM-4 Case

The HDM-4 (Highway Development Management) model used for pavement management activities must be adjusted to the specific conditions of a country or region where they are to be used by adjusting certain calibration factors. The results obtained from calibrating the cracking, raveling, potholing, rut depth, and roughness models contemplated in HDM-4 version 1.1 for surface treatments are presented and compared with the results obtained from equivalent models of HDM-III. In this task, the “windows” methodology was used, which consists of reconstructing the distress performance curve of a specific road category starting with observation of the condition of different roads with similar characteristics (such as traffic, pavement structural capacity, and climatic conditions) but of different ages. On the basis of the results obtained, recommendations for calibrating the performance models are proposed, and calibration factors more adequate for characteristics specific to Chilean surface treatments are established. On comparing the results of the calibrated models of HDM-III and HDM-4, it is concluded that both cases furnish similar values, and use of HDM-4 models is recommended because of their operating advantages and because they afford a greater flexibility, which allows them to more aptly adapt to a broader number of cases and situations.

Modelo de evaluación técnica del desempeño del mantenimiento de pavimentos flexibles

En la gestion de pavimentos es importante evaluar el desempeno de las estrategias de mantenimiento. Esta se realiza mediante modelos tales como HDM-4 a nivel de red. Sin embargo, no siempre se cuenta con calibraciones a nivel de proyecto que permitan precisar los planes de mantenimiento. En este trabajo se propone un modelo de evaluacion tecnica de pavimentos alternativo, que permite comparar planes de conservacion (evaluacion de tipo ex ante) y tambien evaluar el desempeno de los programas de mantenimiento ya ejecutados (evaluacion de tipo ex post), a nivel de proyecto. El modelo considera modelos de prediccion de solicitaciones de trafico, de progresion de rugosidad a traves del IRI, y del efecto de acciones de mantenimiento sobre el IRI. Los modelos fueron calibrados a nivel de proyecto con datos de 2.000 tramos de 200 m de longitud de pavimentos asfalticos emplazados en la red vial de Chile, categorizados por nivel de trafico, clima, tipo de vehiculo y condicion de carga. Asimismo, propone un indicador de desempeno agregado que mide la efectividad de planes de conservacion respecto de una condicion base. El modelo permite cuantificar el desempeno de los planes de mantenimiento segun el tipo de pavimento y optimizar el plan de conservacion de acuerdo a la historia de los pavimentos. Palabras Clave: Optimizacion, mantenimiento, rugosidad, pavimentos.

Asset Valuation of Low-Volume Road Networks: Application to Chilean Unpaved Roads

Asset management is a systematic process of maintenance, modernization, and operation of infrastructure assets in an economically efficient way. For these reasons, asset management has been considered as an emerging concept applied in the area of transport management. Many countries have developed procedures to evaluate pavement infrastructure assets; however, these applications generally have focused on main interurban and urban roads. The objective of this paper is to present a methodology to determine the asset value of low-volume roads and to quantify the impact of maintenance policies on such asset value. As a case study, the proposed methodology was applied to the unpaved road network of Chile, considering different maintenance policies and their impact on the evolution of the road network asset value. A complete analysis that considered the impact of maintenance policies under different budgetary conditions was performed. The analysis was done by using the HDM-4 program, since it performs technical and economic valuations considering a reposition value method. Relationships close to linear were found between final asset value of the unpaved road network under a 20-year valuation. Results showed that medium levels of investment are needed to maintain the network asset value. A small increase of the initial asset value of a network is obtained with high levels of investment. Asset valuation is a good and simple tool that helps agencies during a first-level management process. However, it is not recommended on its own as an optimization tool for the allocation of resources, as social costs and benefits associated with each investment strategy need to be considered.

Roughness of Unpaved Roads: Estimation and Use as an Intervention Threshold

One of the main tasks of the Chilean Dirección Nacional de Vialidad and its regional and provincial secretariats is to determine the maintenance requirements of its roads. In developing countries, most roads managed under this process are unpaved. The traditional way of determining maintenance requirements relies on the criteria applied by whoever inspects the roads. To improve this process, the present work proposes an easy, objective method for determining the conservation requirements of unpaved roads. Roughness thresholds are proposed because they adequately summarize the functional characteristic of this kind of road. Roughness thresholds were determined for different road types after consulting public-, private-, and academic-sector experts who proposed international roughness index (IRI) values based on the characteristics of each road. To measure the roughness of unpaved roads, the use of a response-type roughmeter is recommended. When this type of equipment is not available, it is proposed that IRI be estimated with data obtained from visual inspection. The main distresses of unpaved roads and IRIs were correlated by using data collected from 61 test sections.

Friction Reliability Criteria Applied to Horizontal Curve Design of Low-Volume Roads

Design of road horizontal curves usually considers geometric characteristics and surface pavement condition by means of friction, superelevation, and speed equations in a deterministic point of view: a unique radius and superelevation are selected, considering a uniform behavior of drivers and pavement surface condition. However, empirical evidence shows that operating speed usually exceeds design speed when design speed is lower than 100 km/h. This means that the aggregated friction demand exceeds the design friction. The friction threshold and variability are not considered in design at the present time. Therefore, the designer does not know the remaining friction available and cannot estimate the margin of safety provided by the design. This problem is important in low-volume roads (LVRs) because the design speed usually considered is lower than 100 km/h. In this paper a methodology to design horizontal curves for LVRs is proposed, considering the variability of skid resistance, pavement texture, driver behavior, and geometric design elements. Critical speed is obtained for two conditions: consistency between design and operational conditions and consistency between friction thresholds considered for the pavement surface and operational condition. For this purpose, a reliability index is estimated by using the Hasofer–Lind method. Results show that a more realistic design is obtained when an aggregated friction demand based on driver behavior is considered. A good design is obtained when design speed ranges around 60 km/h and the standard deviation of curve radius is lower than 20% of the mean radius.

Rehabilitation Performance Prediction Models for Concrete Pavements

Successful implementation of a pavement management system requires the necessary simulation tools, among which deterioration prediction models form an important part. These models can be either aggregate or incremental. Aggregate models calculate total accumulated deterioration and require knowledge of the past history of the pavement to predict future behavior. Incremental models, however, require only knowledge of the current pavement conditions. For this reason, incremental models generally are more advantageous when historical pavement condition data are not available. One of the most well-known and widely used methods for pavement evaluation is the World Bank program Highway Design and Maintenance Standards Model (HDM), whose latest version, HDM 4, attempts to accommodate the analysis of both asphalt and concrete pavements. In the case of concrete pavements, the models used are of the aggregate type. Incremental prediction models are used for asphalt pavements. As part of research into the application of incremental models for the prediction of distresses in concrete pavements, rehabilitation performance prediction models in incremental form have been developed and are presented. Rehabilitation performance refers to pavements that already have received repair or rehabilitation to enhance their structural or functional capabilities. The rehabilitation models presented here have been developed by using mathematical combinations of models for new concrete pavements, derived as function of time. The results of validation analyses of the models are presented, along with a discussion of the advantages and disadvantages of the proposed models with respect to existing methods.

Long-term behaviour model of skid resistance for asphalt roadway surfaces

Skid resistance (SR) is relevant to road safety. Several researchers have showed that SR diminishes its value over time depending on the traffic-aggregated interactions, and the presence of heavy vehicles in the traffic stream. The classical SR model shows that its value drops from a starting value to an equilibrium value over time. However, this behaviour in low-volume roads is not entirely true. In this paper, an SR model in a single mathematic specification is proposed, which considers the polishing effect of heavy traffic through the polishing equivalence factor. The model was calibrated by using data measured with a SCRIM device from 1100 test sections in Chile. Considering speed and temperature factors calibrated for Chile, data were processed and corrected. It was concluded that the model for long-term behaviour of SR is satisfactory, but it is necessary to include the seasonal effects for a more realistic model.

Toward Sustainable Management of Low-Volume Roads in Chile: Improvements and Challenges

In the past two decades, Chile has undergone a series of economic and social improvements that have put the country a few steps ahead toward development. For example, Chile has reduced poverty levels by more than 50% in less than 20 years. It is widely recognized that increasing the access of the population to basic services such as health and education is a key factor influencing development. The provision of low-volume roads (LVRs) is essential to offering that access, which should also rely on proper levels of service through sustainable management. The objective of this keynote is to describe Chiles main experiences concerning sustainable management of the LVR network and the challenges Chile will face in the future. Chiles experience with the LVR network can serve as an example for other developing countries in the same way that the countrys implementation of the concession model (or public–private partnerships) did for its system of main highways a few years ago.