Officer's signal: CAUTION (preventiva)

The CAUTION (preventiva) signal is the GO position plus one arm raised horizontally with the hand extended upward on the side traffic is coming from (or both arms, for two-way traffic). It warns that the officer is about to change from GO to STOP (Article 306, section III). Drivers must take precautions; pedestrians must not start crossing, and those already crossing must hurry.