We heard Transports Québec is considering updating highway traffic signs. This may also be a good time to take a look at the city’s street signs. Maybe you’ve caught yourself wondering about their usefulness and asking yourself “Just how easy are these signs to understand?”

Imagine the following scenario: It’s Monday morning at 8 am. You’re driving to work on a two-way, four-lane street. Let’s say Sherbrooke St. in Montréal. You’re heading east and traffic is heavy. You want to turn left at the next intersection. However, at that intersection, you spot a street sign below the street lights. You have only a few seconds to read and understand the sign.

Do you think you have the right to turn left?
Let’s try to understand this sign: It says that drivers must go straight or turn right from Monday to Friday, between 3 pm and 6 pm.

So, can you turn left? OF COURSE! What this sign says is that left turns are prohibited from Monday to Friday, between 3 pm and 6 pm. So you do have the right to turn left at 8 am.
Does that mean that, at times other than those indicated on the sign, going straight and turning right are prohibited?

Who was this sign made for?
Certainly not for drivers who wish to go straight or to turn right, because this is permitted at any time. This sign must then have been made for drivers who wish to turn left.

Let’s take a quick look at the task involved here:
In the space of a couple of seconds, the driver must perform some serious mental acrobatics. While simultaneously scanning the road ahead, holding the wheel and working the pedals, the driver must:

• ­ notice the sign;
• ­ watch how close the vehicle behind is getting in the rear-view mirror;
• ­ apply to brake to slow down enough to read the sign;
• ­ read the sign;
• ­ understand the sign;
• ­ remember what day of the week it is;
• ­ check the time on her watch, on the car’s dash or guess it;
• ­ deduce the following: “If I’m supposed to go straight or turn right, from Monday to Friday, between 3 pm and 6 pm, that means turning left is prohibited during those hours, but, as it is only 8 in the morning, I’m in the right”;
• ­ decide to turn left;
• ­ scan the road ahead, to the right and the left;
• ­ check the rear-view mirror;
• ­ if it is necessary to change lanes, signal for the lane change;
• ­ get into the left-hand turning lane; and,
• ­ turn left.

Would it be possible to simplify this sign?
Well, we could possibly create a sign directed at the end user – the driver who wishes to turn left instead of those who are going straight or turning right – and tell him that turning left from Monday to Friday, between 3 pm and 6 pm, is prohibited.

In the above situation, which of the two signs would be easiest for you to decode? The mandatory action or the prohibited action?