Estudios de navegación y riesgos para la construcción de infraestructuras sobre vías navegables: puente Vidin-Calafat (Danubio) o el nuevo puente sobre la bahía de CáNavigation and risk studies for the construction of infrastructures on waterways: Vidin-Calafat bridge (Danube) and the new bridge over the bay of Cádiz (Spain). This approach covers human error (navigation, positioning and steering decision errors, etc.) as well as vessel breakdowns (propulsion, steering and instrumentation, etc.) which may lead to a collision with the infrastructure or running aground, in addition to the difficulties imposed by the chart for the waterway or the weather conditions.diz (España).