Before changing lanes, how should you signal?

Signals must be given clearly, with sufficient advance notice before beginning the manoeuvre, and as a general rule using the vehicle's indicator lights, or failing that, with the arm. Signals given with the vehicle's indicator lights must remain active until the manoeuvre they are signalling is complete. If there is a contradiction between the signal made with the driver's arm and the vehicle's indicator lights, we must follow what the driver indicates, as the indicator lights may be faulty. Brake lights are used to indicate to drivers behind that the vehicle is braking or that we want to reduce speed considerably. Acoustic signals, i.e. the horn, may be used to avoid accidents, when performing an urgent service, and on narrow roads with many bends, both on urban and interurban roads. It may also be used to warn of an overtaking manoeuvre, but only on interurban roads.