You cannot make a U-turn on a solid yellow line. According to the relevant regulations of the "Road Traffic Safety Law of the People's Republic of China": whether it is a single yellow line or a double yellow line, if it is solid, you cannot cross it. Circumstances under which U-turns are allowed: Presence of U-turn signal lights or signs: When there is a U-turn signal light at an intersection, you can make a U-turn when the U-turn indicator is green; if there is a U-turn sign at the intersection or a U-turn indicator on the lane, you can make a U-turn while ensuring the safety of yourself and others. No U-turn signs but left turns are allowed (no prohibition of U-turn signs or markings): Vehicles can make a U-turn at intersections where left turns are permitted and no prohibition of U-turn signs or markings are set. It should be noted that vehicles must proceed according to the left-turn lane signal without affecting the normal driving of other vehicles. If you want to make a U-turn at an intersection with a left-turn waiting area, you can first enter the left-turn waiting area when the straight-through light is green and wait until the left-turn light turns green before making the U-turn. U-turns are allowed at dashed lines: Whether it is a white dashed line or a yellow dashed line, U-turns are permitted. For double yellow lines with one solid and one dashed, check if your side is the dashed line. If it is, you can make a U-turn safely; if it is solid, U-turns are not allowed.
