Temporary traffic lights that won't turn green? It turns out you may not be close enough to trigger the sensor.
The UK is experiencing a rise in roadworks as local councils continue to spend the £1.6 billion earmarked by the government to fill potholes and repair decayed roads.
More roadworks means more temporary traffic lights. And understanding how the sensors on some traffic lights function can stop you being perpetually staring at a red bulb waiting for it to turn green, according to experts.
Motoring expert Graham Conway, Managing Director at Select Car Leasing, explains: "Nobody enjoys being stuck at a traffic light waiting for it to turn green - but we suspect many motorists simply aren't aware that their own driving habits could be making the problem worse.
"Many temporary traffic lights use radar sensors that require a vehicle to be close enough to trigger the light change.
"If a vehicle isn't near enough, the lights will prioritise traffic coming from another direction where they can sense cars - leaving you unnecessarily stuck on red for an age.
"This can cause a traffic jam to build in one direction, which can take many rotations of the lights to clear, and potentially causing anger and frustration all round."
But, frustratingly, the same issue can be caused if a driver stops too close to the light itself, beyond the sensor.
"The light will then only change if someone pulls up behind them and triggers the sensor again," says Graham.
While some temporary lights run on timers, others use sensors to understand where the traffic is, and which direction needs to be let through first.
These systems use microwave radar sensors (or microwave vehicle detectors - MVD) to detect approaching vehicles and adjust signal timings accordingly.
They send a signal to the controller when an approaching vehicle is detected, allowing the lights to change and to manage traffic flow more efficiently.
But failing to get close enough to the traffic light - and to therefore trigger the sensor - means you could be waiting an eternity for it to turn green.
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While true of traffic light systems of the past, modern temporary traffic lights (or 'TTLs') aren't designed to function in such a way as they don't have light-based sensors.
"The sensors in modern traffic lights don't respond to the light frequencies emitted by headlights - so it's pointless flashing your lights at them in an attempt to speed-up the colour change process," says Graham
"You also risk dazzling other road users, which is an offence that risks a charge of driving without due care and attention.
"If you misuse your headlights, most drivers can expect a £100 fine and points on your licence, while more serious cases could see the fine hiked to £5,000 coupled with the threat of a driving ban."