Ireland Truck & Bus Theory Test key terms

The default maximum speed that applies on a road type when no sign shows a lower figure. In Ireland motorways allow 120 km/h, national roads 100 km/h, regional and local roads 80 km/h, and built-up areas 50 km/h.

A default 50 km/h limit that applies within a town or city boundary, marked by a white rectangular sign showing the place name, unless signs show a different limit.

A circular white sign with a red border showing a number in black, which sets the maximum permitted speed in kilometres per hour on the road ahead.

A solid white centre line that must not be crossed except to avoid an obstruction or in an emergency. It warns that overtaking is too dangerous because forward visibility is restricted.

A dashed white centre line that may be crossed to overtake or turn when it is safe. Longer dashes with shorter gaps warn that a continuous line is approaching.

Passing another road user travelling in the same direction. It must be completed on the right, with clear road, adequate gap and enough distance to return safely before any solid line or hazard.

A yellow criss-cross marked area at a junction. A driver may enter only when the exit is clear, and must not stop inside it, so cross traffic is never blocked.

The painted yellow cross-hatched grid on the road surface that defines a box junction and signals that the area must be kept clear of stationary vehicles.

A circular junction where traffic already on the circle has right of way. Drivers approach with care, give way to the right, signal intentions and choose the correct lane for their exit.

To slow or stop and let other traffic proceed first. It is shown by an inverted triangle sign or road markings and requires yielding without forcing others to brake or swerve.

A red octagonal sign reading STOP that requires a complete halt at the line before proceeding, regardless of whether any traffic is visible.

Keeping to the correct lane, staying centred within it, and changing lane only after checking mirrors and blind spots and signalling in good time.

A high-speed road restricted to vehicles capable of a minimum speed, with no pedestrians, cyclists or slow vehicles. It has a 120 km/h default limit and a hard shoulder for emergencies only.

The strip at the edge of a motorway marked by a continuous yellow line. It is for emergencies and breakdowns only, not for driving, stopping or overtaking.

Pulling onto the hard shoulder when a vehicle breaks down, then switching on hazard lights, placing a warning triangle well behind the vehicle and moving people to safety behind the barrier.

The area around a vehicle that cannot be seen in the mirrors. A driver must turn the head to check it before moving off, changing lane or turning, especially with large vehicles.

Looking in the interior and exterior mirrors before signalling, changing speed, changing lane or opening a door, to build a picture of traffic behind and beside the vehicle.

A sequence used at every hazard: Mirrors, Signal, Position, Speed and Look. It structures observation and preparation so manoeuvres are planned and communicated before they happen.

Giving clear, timely information to other road users with indicators or hand signals about an intended change of direction or speed, then cancelling the signal afterwards.

A method of judging a safe following gap in good, dry conditions by counting two seconds between the vehicle ahead passing a fixed point and your own vehicle reaching it.

The total distance travelled from the moment a hazard is seen until the vehicle stops, made up of thinking distance plus braking distance. It grows with speed, load and poor grip.

The distance covered while the brakes are actually slowing the vehicle, after the driver has reacted. It increases with the square of speed and is longer on wet, icy or loose surfaces.

Driving too close behind the vehicle ahead, leaving no room to react if it brakes suddenly. It is a major cause of rear-end collisions and is especially dangerous for heavy vehicles.

Loss of tyre grip when a layer of water lifts the tyres off the road surface at speed. Steering and braking become ineffective, so the driver should ease off the accelerator and avoid harsh inputs.

All four indicators flashing together to warn others of a stationary or slow-moving hazard, such as a breakdown, a queue or an obstruction ahead.

A reflective red triangle carried in the vehicle and placed on the road behind a broken-down vehicle to warn approaching traffic, at a distance suited to the road and visibility.

The depth of the grooves cut into a tyre. Irish law requires at least 1.6 mm across the central three-quarters of car and light vehicle tyres, with higher minimums for larger vehicles.

The air pressure inside a tyre, which must be checked cold and set to the manufacturer's figure. Wrong pressure harms grip, wear and fuel use, and can cause a blowout.

A walk-around inspection before driving covering tyres, lights, mirrors, fluids, load security and couplings, intended to catch defects before the vehicle reaches the road.

Restraining and distributing a load so it cannot shift, fall or make the vehicle unstable, using straps, curtains or restraints and staying within permitted axle and gross weights.

The maximum permitted total weight of a vehicle together with its load, set by the manufacturer and shown on the vehicle plate. Exceeding it is an offence and affects braking and handling.

The load carried by a single axle or axle group. Each has its own legal maximum, and overloading one axle can make a vehicle unstable even when total weight is legal.

The legal limits on driving and working time for professional drivers, including daily and weekly driving maximums, required breaks and daily and weekly rest periods.

The maximum time a professional driver may spend driving in one day, normally nine hours, which may be extended to ten hours twice in a week under EU rules.

After a set period of driving a professional driver must take a qualifying break, commonly 45 minutes after four and a half hours, which may be split into two parts.

A recording device fitted to goods and passenger vehicles that logs driving, other work, availability and rest, providing evidence that drivers' hours rules are being followed.

A personalised smart card inserted into a digital tachograph to identify the driver and record activity. It must be kept in good condition and not used by anyone else.

A record added by the driver to the tachograph to account for work, rest or availability not captured automatically, such as time spent on other duties before inserting the card.