Volume 20, No. 35Journal 35

Fidel García Hernández, Horacio Delgado Alamilla, Domingo Eduardo Campos Hernández (Author)

Influence of design variables on the mechanical properties of a stabilized base with foamed asphalt

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The construction and conservation of new roads requires many natural and economic resources, so the recycling is one of the most used techniques currently, so it is important to understand the mechanical properties of the type of application to be used.
The present paper focuses on the evaluation of the mechanical properties of a stabilized base with foamed asphalt (cold recycled). The study analyzed the influence of two design variables such as the type of active filler (lime and cement) and the content of foamed asphalt (2.2 to 2.4%). The parameters used in the evaluation were indirect tensile strength, friction angle and cohesion (triaxial test) and resilient modulus (MR).
The results indicate that the addition of lime improves the mechanical properties of the stabilized base. Regarding mechanical parameters, it was observed that the stabilized mixtures with foamed asphalt show an increase in their resistance compared to a granular base, being the loss of cohesion the failure mode of this type of stabilization.

Rodrigo Arias García (Author)

Environmental and socioeconomic criteria to prioritize investments in the road network of Costa Rica

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Given the absence of a formal implementation of a Pavement Management System for the National Paved Road Network of Costa Rica, there are no long-term planning processes of investments in the pavements. The research presented herein aims to demonstrate, in addition to the feasibility of perform long-term investment plans (20 years), that prioritization criteria on environmental, social and economical aspects can be included in the plan.
For the preparation of investment plans, the condition of the pavement was estimated through an index composed of functional capacity and structural capacity in each section of the National Road Network. Each of these sections contains characteristicsreferring to traffic, route hierarchy and others. Subsequently, costs of maintenance techniques are estimated using contract 2014LN-000018-0C00.
Through Woodstock software, linear optimization techniques were used to carry out investment scenarios incorporating different prioritization criteria. In this way, the Social Progress Index, the Cantonal Competitiveness Index and the CO2 emission are used as criteria to prioritize investments in the sections of the National Paved Road Network of Costa Rica.
With the results, it is possible to confirm the feasibility of preparing longterm investment plans based on the inputs available in Costa Rica. In addition, it is observed that the budget increases have a greater effect on the lapse with which a better condition of the pavements is achieved than in the condition itself. Likewise, the reduction of CO2 emissions will have an impact on the condition of the network, since reconstruction interventions are those that require activities with a higher emission of pollutants.

Luis Diego Herra Gómez (Author)

Conceptualization of Digital Image Processing for the Evaluation of Pavement Surfaces in Costa Rica

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The timely attention of a road system through minor maintenance activities, such as potholes repair techniques and crack sealing, is a practice recognized for its good cost-benefit ratio, by preventing the pavement from an accelerated deterioration dueto the effect of climate and transit, reducing the need of major and expensive interventions.

However, although minor maintenance activities can be very beneficial, in Costa Rica, identifying road segments that requirethesetypes of interventions is a work that could be biased to the criteriaof those who perform the visual auscultation of deteriorations, and depending on the route that is being evaluated, it could be a dangerous activity in terms of road safety.
Given this scenario, it is necessary to have automated processes that allow generating an inventory of preventive maintenance needs in an agile, objective and safe manner. To do this, there are currently several alternatives that allow automating the count of preventive maintenance needs of a road, being digital image processing one of the most used.
The digital image processing allows, by using algorithms applied to a road photographic record, to define intervention criteria for minor maintenance activities, in order toidentify with greater certainty the deteriorations under a certain threshold of severity present in a road.
In this way, the digital image registry could be considered as a very valuable input to improve efficiency in terms of the investment made in a certain road system, without forgetting that this type of tools are a complement that should not replace the technical criteria of th e professionals in charge of the road management system.

Verónica Solís Salas (Author)

Surface roughness specifications context in costa rican rehabilitation projects

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To guarantee pavement performance in rehabilitation projects with asphalt overlays, the implementation of technical specifications that enables the assessment of its construction quality is necessary. The applicability of the specifications must be validated in terms of achieved values from past projects altogether with international references, where similar specifications have gone into effect, followed up with the validation of the results. In the present project, the applicability of the specifications from the Manual of general specifications for road and bridge constructions in Costa Rica is analyzed with the requirements of bid paper N°2014LN- 000018-0CV00 for nine projects with asphalt overlay interventions in the last two years. From the investigation it can be concluded that the established range of values in the specifications matches the ones in countries like Chile, Colombia, Spain and United States. Additionally, the results showed that, even though said specifications were not valid for the bid paper, acceptable compliance was achieved, which indicates the applicability of the normative in the Costa Rican reality. Finally, as a product of the investigation, improvements for the current specifications were defined, where these can be verified in actual projects.

Ricardo José Chacón Vega (Author)

Classification and Allocation of Risks in Infrastructure Projects Developed through Public–Private Partnerships (PPP) in Costa Rica

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The Public-Private Partnerships (PPP) model for the development of public infrastructure has changed from being perceived only as a finance model, to be considered a management model. Beyond its well-known advantages (such as involving private funding and reducing public debt), it is nowadays considered as the best way for transferring the risks from the public to the private sector. This risk allocation between the public and private parties is one of its critical success factors, hence it is critical to focus in this topic to guarantee the success of future projects. Despite of its relevance, the process of risk allocation has often been poorly executed around the world, and Costa Rica has not been the exception.

In Costa Rica, the process of risk identification in PPP projects has failed on comprising all the existing risks, and this situation has had a negative impact in them. The identification, classification and allocation of risks is the foundation of a good management of PPP projects. Therefore, this article aims to provide professionals(locals and foreigners), policy makers, investors and researchers a better understanding of risk allocation i npublic infrastructure projects developed through PPP, and to help future research and projects.