On roads outside a built-up area with no usable pedestrian area, which pedestrians must always keep to the right?

Correct answer: Those pushing or pulling a bicycle.

If there is no usable pedestrian area, pedestrians walk on the left as a general rule. Those pushing or pulling a bicycle, a two-wheeled moped or a personal mobility vehicle, groups led by one person, and those who, for safety reasons, should not walk on the left must always keep to their right and obey traffic officers' instructions and traffic signs. Someone herding animals or pushing a motorcycle is not a pedestrian but a driver. Wheelchair users follow the general rule for pedestrians.

Real Decreto 1428/2003, de 21 de noviembre, por el que se aprueba el Reglamento General de Circulación · Real Decreto Legislativo 6/2015, de 30 de octubre, por el que se aprueba el texto refundido de la Ley sobre Tráfico, Circulación de Vehículos a Motor y Seguridad Vial