Georeferencing field plots by means of GPS/GLONASS techniques is becoming compulsory for many applications concerning forest management and inventory. True coordinates obtained in a total station traverse were compared against GPS/GLONASS occupations computed from one navigation-grade and three survey-grade receivers. Records were taken under a high Pinus sylvestris L. forest canopy situated in a mountainous area in central Spain. The horizontal component of the absolute error was a better descriptor of the performance of GPS/GLONASS receivers compared to the precision computed by the proprietary software. The vertical component of absolute error also failed to show the effects revealed when the horizontal one was studied. These differences might be critical for applications involving high-demanding surveys, in which a comparison against a terrestrially surveyed ground truth is still mandatory for accuracy assessment in forested mountainous areas. Moreover, a comparison of diverse Differential GPS/GLONASS techniques showed that the effect of lengthening the baseline and lowering the logging rate was not significant in this study. Differences among methods and receivers were only observed for recording periods between 5 and 15 minutes. The hand-held receiver was inappropriate for plot establishment due to its inaccuracy and a low rate of fixed solutions, though it may be used for forest campaigns tolerating low precision or permitting the employment of periods of 20 minutes or longer for plot mensuration.Additional key words: forest inventory; georeferencing; global navigation satellite system (GNSS) (GLONASS); optimum observing time. Resumen Exactitud y precisión de receptores GPS bajo cubiertas forestales en ambientes montañososLa georreferenciación de trabajos de campo por medio de GPS/GLONASS es cada vez más necesaria para muchas aplicaciones en la gestión e inventario forestal. Se compararon coordenadas reales levantadas con estación total con las obtenidas por un navegador y tres equipos de calidad topográfica. Los registros se efectuaron bajo una masa de Pinus sylvestris L. del Sistema Central, España. La componente horizontal del error absoluto resultó ser un mejor descriptor de la calidad de las mediciones de los receptores GPS/GLONASS que los valores de precisión proporcionados por el software de los equipos. La componente vertical del error absoluto no mostró los efectos revelados por la componente horizontal. Estas diferencias pueden ser críticas para trabajos que requieran levantamientos topográficos de precisión, en los cuáles un contraste con itinerarios de validación sobre el terreno sigue siendo indispensable para calcular la exactitud en áreas forestales montañosas. Por otro lado, la comparación de diversas técnicas de GPS/GLO-NASS diferencial mostró que los cambios en la longitud de la línea base y de la tasa de registros no fueron significativos en este estudio. Sólo se observaron diferencias ente los métodos y receptores para tiempos de registro de 5 a 15 minutos. El navegador no resu...

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Given the high number of crashes occurring on highways, it is necessary to intensify the search for new tools that assist in understanding their causes. With this aim in mind, the authors have developed a computer system, named Highway Design Analysis (HDA), which analyses the relationship between the geometric characteristics of a highway and those characteristics that the driver expects to find. The system is based on the analysis of vehicles' operating speed and allows the selection of the operating speed prediction model to be used. Several speed prediction models, including the model developed in Spain in the current study, have been used in the case study. The information generated by the application developed has been integrated into a geographic information system (GIS) with the purpose of manipulating, analysing and showing the results in a more efficient way. The system developed is discussed along with its application to three highways.