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.
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.
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.
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.
IntroducciónDesde el punto de vista de los usuarios, la gestión del mantenimiento de pavimentos tiene por objetivos: otorgar al usuario confort y seguridad; mantener la calidad funcional del pavimento (resistencia al deslizamiento, apariencia, etc.), mantener bajos los costos de operación del usuarioEstos objetivos se traducen, desde el punto de vista del administrador de la red vial, en la necesidad de mantener un exhaustivo seguimiento de la condición del pavimento y de diseñar estrategias para optimizar las acciones de mantenimiento, tanto desde un punto de vista de los flujos de caja (inversiones) como del impacto que genera al usuario las intervenciones en la red.Por lo tanto, los administradores de las rutas requieren de programas o modelos precisos para reducir la incertidumbre en la planificación de las inversiones necesarias para alcanzar un cierto estándar de los pavimentos de la red.En este artículo se propone un modelo de evaluación del desempeño de las acciones de mantenimiento de pavimentos que permite comparar planes de mantenimiento (evaluación de tipo ex ante) y evaluar el desempeño de programas de mantenimiento ya ejecutados (evaluación de tipo ex post). El modelo propuesto se basa en el índice de rugosidad internacional (IRI) para evaluar el estado global del pavimento. Se optó por este indicador debido a que representa de manera directa la condición funcional de un pavimento, y a su vez constituye un indicador complementario importante para sectorizar la red según su capacidad estructural. La metodología considera 6 etapas, como se muestra en la Figura 1.Abarcando la revisión exhaustiva de diversas investigaciones, este estudio se aboca a la obtención de curvas de comportamiento (en función del IRI) específicas para distintos tipos de pavimentos mediante un análisis a nivel de red. A partir de estas curvas se busca cuantificar el desempeño de distintos planes de conservación, que incluyen un conjunto de acciones individuales de mantenimiento, a nivel de proyecto y en base a indicadores de desempeño y modelos que reflejen el efecto de distintas intervenciones.En este artículo se revisa, en primer lugar, el estado del arte acerca de modelos de evaluación y optimización del mantenimiento. Luego se presenta la metodología propuesta, en donde se verán los procedimientos, fór-mulas y parámetros utilizados para clasificar los distintos tramos de pavimentos flexibles incluidos en el estudio. Posteriormente se explican los conceptos considerados para el desarrollo de las curvas de comportamiento en función del IRI. En la última parte se incluyen las modelaciones e indicadores que permiten estimar la efectividad de distintos tipos de intervenciones. Finalmente se incluye un caso de aplicación del modelo y las conclusiones del trabajo. Figura 1 Etapas del modelo de evaluación del desempeño del mantenimiento de pavimentospáginas: 76 -88[ 79 Revista de la ConstrucciónVolumen 9 N o 2 -2010
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