In what order will vehicles drive through the intersection if the traffic lights do not work?

Explanation

First the motorcycle, then the bus and the passenger car, and last the trolleybus.

The lights hanging on the gantry in the picture are switched off. A switched-off light has the same effect as a flashing amber: the junction leaves the "signalled" state and becomes an uncontrolled junction. From that moment the order of passage is set by the priority signs and, in their absence, by the "obstacle on the right" rule; that is, every driver must give way to the vehicle coming from his right.

That rule alone solves the whole scene. The motorcycle, the vehicle nearest the camera, has an empty right and nobody precedes it, so it goes first. The bus and the passenger car, coming from the left of the frame towards the right, have the motorcycle on their right; so they follow it and, being in the same direction, pass together. The trolleybus, reaching the junction from the street on the right, has the bus and the car on its right and is last.

Worth memorising, and the main trap of this question: a trolleybus is not a rail vehicle. The only vehicle with precedence over non-rail vehicles at an uncontrolled junction is the tram. A trolleybus, a city bus and a minibus all count as ordinary vehicles, and drawing current from an overhead wire gives them no advantage.

The safety reason is clear too: when the light fails, the real danger is that each driver assumes "it must be my turn". The right-hand rule provides a fixed, predictable reference so that two cars do not enter the middle of the junction at once.

• This puts the trolleybus level with the motorcycle at the head of the queue; that is the common mistake of granting a trolleybus the tram's advantage. • This sends the bus and the car ahead of the motorcycle, whereas the motorcycle is on their right and they must give way to it; a motorcycle being small does not reduce its priority.

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