The legal limit, the safe limit, and what holding up traffic actually costs
Every road has two speed limits running at once. There’s the legal maximum, which is a ceiling, not a target, and there’s the safe limit, the speed at which you can stop within the distance you can actually see to be clear. Good driving lives at whichever of the two is lower, and knowing both, at all times, is the foundation everything else in this article sits on.
Knowing the Limit
Two things tell you the legal limit when there’s no sign confirming it. Regular street lamps, roughly 200 yards or 185 metres apart, mean 30 mph. Repeater signs, about the size of a dinner plate and roughly every four lamp posts apart, take priority over street lamps when both are present. No lamps and no repeaters means national speed limit, 60 mph for a car on a single carriageway, 70 mph on a dual carriageway with a central reservation or physical barrier.
Knowing the limit is only half of it. You should be equally certain, at any moment, of the actual speed you’re travelling.
Too Fast, Two Ways
There are two separate ways to be going too fast, and they’re not the same problem. Speeding is exceeding the legal limit for the road, a legal problem with legal consequences, points, a fine, potentially your licence. Driving too fast for the conditions is different, and often more dangerous, doing 30 in a 30 during heavy rain, or in fog, or with a road full of pedestrians, can be entirely legal and still entirely reckless. A pupil needs both concepts, not just the one with a number attached to it. This second kind is still a traffic offence in its own right, driving without due care and attention, whether or not the speedometer ever shows a number above the limit.
Too Slow
Progress that’s too slow has its own costs, even though there’s no fine attached to it. Driving well under the limit for no good reason holds up following traffic, breeds frustration, and encourages the drivers behind you to attempt the most dangerous manoeuvre on the road, overtaking, simply to get past you. Hesitancy isn’t the same as caution. A driver who’s reluctant to make reasonable progress isn’t being safe, they’re transferring risk onto everyone stacking up behind them. This too can amount to a traffic offence, especially on a motorway, where driving unreasonably slowly without cause can itself be treated as careless or obstructive driving.
Change of Speed Limit
Whenever the limit changes, higher or lower, check your mirrors before you respond to it. Moving into a higher limit, check the rear view mirror and the offside mirror to see if anyone’s already overtaking before you accelerate away from them. Moving into a lower limit, check the rear view mirror before you brake, so you’re not caught out by someone following closer than you’d assumed.
Why This Matters for Teaching
Pupils are far more often taught to fear going too fast than they are taught the cost of going too slow, which leaves them with an unbalanced picture of what good driving actually looks like. A pupil who crawls well under the limit out of nervousness is exhibiting a fault just as real as one who speeds. Both leave a driver anxious, and both make them aware, uncomfortably, that they’ve become the reason everyone behind them is held up, which can just as easily provoke frustration or abuse from following traffic as speeding does. Teaching progress as a positive skill in its own right, not just the avoidance of speeding, is what closes that gap.
Next in the series: Meeting, Crossing, and Overtaking, covering priority when passing oncoming traffic, and the system for a safe overtake.
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