Is a trailer passenger car allowed in a straight line at this intersection?

Explanation

Yes, passing straight ahead is permitted.

The round sign with a red border and the image of a lorry, posted in the picture above the straight route, is "no entry for lorries". When no figure is written on this sign, it prohibits the movement of lorries with a permissible mass over 3.5 tonnes. A passenger car — even when towing a trailer — is not a lorry and is not covered by this sign; so you may pass straight through this junction.

The trap in the question is precisely the word "trailer". The candidate's mind equates a trailer with carrying goods and carrying goods with a lorry. But in the sign system there is a separate sign for prohibiting movement with a trailer, and until that sign is posted, a passenger car towing a trailer is as free as any other passenger car.

The reason for this distinction is technical: what the "no lorries" sign prevents is the heavy axle load, great length and long braking distance of goods vehicles, not the mere fact of having a trailer. This does not mean carelessness, of course; with a trailer the length of the combination is greater and braking is weaker, so keep a longer safety distance and take a wider arc at junctions so the trailer does not cut the corner.

• The "residents of the area only" exception relates to certain prohibitory signs; but here the sign does not cover passenger cars in the first place and no exception is needed. • "No" comes from the notion that a trailer turns a passenger car into a goods vehicle; but the sign speaks about the type of vehicle and its own permissible mass, not about the trailer.

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