Saudi Heavy Vehicle Theory cheat sheet

Saudi traffic law is enforced under the Traffic Regulations issued by the Ministry of Interior (Muroor); violations are recorded against the driver's licence and the vehicle plate, and fines escalate for repeat offences within the same year.

Regulatory signs (red circle or red triangle) impose legal duties: STOP means a full halt at the line, YIELD/GIVE WAY means give priority to traffic already on the road, and a red circle with a number is a maximum permitted speed.

Warning signs are triangular with a red border and yellow or white background; they announce hazards ahead such as bends, steep descents, junctions, camels or livestock crossing, and loose gravel.

Information and direction signs are rectangular and blue or green; on Saudi highways green signs indicate long-distance routes and destinations, blue signs indicate local roads and services.

Solid white edge lines mark the outer limit of the carriageway; a solid centre line may not be crossed, while a broken centre line may be crossed only when it is safe and the overtaking manoeuvre can be completed.

Heavy vehicles are generally restricted to the right-hand lane on multi-lane highways and must not use the left lane except to overtake or to follow a mandatory direction sign.

A vehicle must not stop or park on a pedestrian crossing, within an intersection, on a curve or crest where visibility is limited, or on a motorway hard shoulder except in an emergency.

Seat belts are mandatory for the driver and all passengers; using a hand-held mobile phone while driving is prohibited and carries a fine and licence points.

At a roundabout, traffic already circulating has priority unless signs or signals indicate otherwise; heavy vehicles must signal exit and check the blind spot on the right before leaving.

Saudi driving licences are graded by vehicle class: light vehicle, heavy vehicle (truck), bus, and heavy equipment; a heavy vehicle licence is required to drive a truck whose permissible gross weight exceeds the light vehicle threshold.

A heavy goods vehicle licence does not authorise driving a bus for passenger transport; a separate bus category is required, and passenger-carrying vehicles face stricter medical and experience conditions.

Permissible gross vehicle weight (GVW) is the maximum laden weight declared by the manufacturer; gross combination weight (GCW) applies to a tractor unit plus trailer and must not be exceeded.

Axle load limits apply per axle and per axle group; overloading a single axle is an offence even if total vehicle weight is legal, and it increases tyre failure and brake fade risk.

Loads must not project beyond the vehicle's sides or rear without the prescribed markings and, where required, a permit; projecting loads must be flagged and, at night, marked with reflective material.

Trailer towing requires the correct licence endorsement, a serviceable coupling and safety chains or an equivalent secondary connection, plus functioning trailer brakes and lights.

Drivers of heavy vehicles must carry a valid licence for the class, the vehicle registration (istimara), and proof of valid insurance; driving without valid insurance is a separate offence from driving unlicensed.

Licence validity is time-limited and renewal requires a medical fitness examination; certain medical conditions and vision standards disqualify a driver from the heavy vehicle category.

Periodic technical inspection (fahs) is required at intervals set by the licensing authority; a vehicle without a valid inspection certificate cannot be legally registered or operated on public roads.

Daily pre-trip walk-around covers tyres (tread depth, cuts, bulges, inflation, dual tyre spacing), wheel nut indicators, lights and reflectors, mirrors, wipers, horn, and visible fluid leaks.

Under the bonnet: engine oil, coolant, brake fluid, power-steering fluid, washer fluid, belt condition and battery security; low coolant or oil is a stop-and-fix item, not a monitor item.

Air system check: with the engine off and tanks full, pressure should not drop more than the manufacturer's limit in one minute with brakes released; a steady or rapid loss indicates a leak.

Low-pressure warning must activate before pressure falls below the safe operating threshold (typically around 4.5–5.5 bar / 65–80 psi); the system must build from zero to governor cut-out within the specified time.

Brake tests before moving: parking brake holds the laden vehicle on a gradient, service brake pedal feels firm with no sponginess, and the low-pressure buzzer and light both work.

Tyres on the same axle must match in size, construction and tread pattern; tread depth below the legal minimum, exposed cord, or sidewall damage means the vehicle is unroadworthy.

Load security is part of roadworthiness: check that tarpaulin, ropes, straps, twist locks and container pins are intact and that the load cannot shift under braking or cornering.

A heavy vehicle air system typically runs at 8–8.5 bar (about 115–125 psi) governed pressure; the compressor refills the tanks and cuts out at the governor setting, cutting back in at a lower pressure.

The supply circuit feeds the trailer through the emergency (supply) line; a loss of supply pressure triggers the trailer relay valve to apply the trailer brakes automatically - the breakaway protection function.

The service line carries the control signal from the foot valve to the trailer; on a dual-line system, losing the service line alone reduces braking but does not by itself apply the trailer brakes.

Air brake application is progressive: pedal travel controls the relay valve, which admits tank pressure to the brake chambers; a full application is not needed for normal stops and causes unnecessary heat.

Brake fade occurs when drums and linings overheat on long descents; control speed by selecting a low gear before the descent and using intermittent braking, never by riding the brakes continuously.

An engine brake or retarder assists on descents but does not replace the service brake; on slippery surfaces it can cause drive-axle lock-up, so it must be switched off or reduced.

Spring brakes are applied by mechanical spring force when air pressure is released; they serve as the parking brake and apply automatically on catastrophic pressure loss.

Stopping distance = perception distance + reaction distance + braking distance. Reaction distance ≈ speed (m/s) × reaction time; at 90 km/h (25 m/s) a 1.5 s reaction alone covers about 37 m.

Braking distance rises with the square of speed: doubling speed roughly quadruples braking distance, and a fully laden vehicle needs substantially more distance than an empty one.

Use a minimum following gap of at least 3 seconds in good conditions; increase to 4 seconds or more when laden, at night, in rain, or when visibility is reduced by dust or spray.

At 100 km/h a vehicle covers about 28 m per second, so a 3-second gap is roughly 83 m; the gap must be measured from a fixed roadside object, not estimated by eye.

Adjust speed so that the vehicle can stop within the distance seen to be clear; on a crest, in fog, or in blowing dust, the visible distance - not the posted limit - sets the safe speed.

Descend long gradients in the same gear that would be needed to climb them; if the vehicle accelerates in that gear, select a lower gear before speed builds.

Overtaking requires clear sight distance, a legal broken line or permitted zone, and enough road to return to the right lane; heavy vehicles need far more overtaking distance than cars.

Increase the gap when following another heavy vehicle: the taller vehicle blocks forward vision, so the driver cannot see hazards, signals or stopped traffic ahead.

Maintain lane discipline, use mirrors systematically before any lane change, and account for the large blind spots directly in front, on both flanks and behind a long trailer.

On sand, gravel or wet roads, reduce speed and avoid sudden steering or braking inputs; a laden truck has high rollover risk in fast lane changes and on highway off-ramps.

Total laden weight must not exceed the permissible GVW, and each axle or axle group must remain within its rated limit; distribute load so no single axle is overloaded.

Keep the centre of gravity as low and as close to the drive axles as possible; a high or rearward centre of gravity reduces steering-axle grip and increases rollover risk.

The drive axle needs adequate load for traction; an empty or lightly loaded drive axle on a tractor reduces grip, especially on sand or in rain.

Secure cargo with rated straps, chains, binders or twist locks; the aggregate lashing strength must be sufficient for the load, and every attachment point must be sound.

Loads must be restrained against forward, rearward and lateral movement; a load that can shift under emergency braking can push through the cab or destabilise the vehicle.

Check lashings after the first few kilometres and at each stop; straps stretch, knots loosen and loads settle, so a load secure at departure may not be secure an hour later.

Cover loose loads such as sand, gravel or aggregate with a tarpaulin so material cannot spill onto the road or strike following traffic.

Overhanging loads require warning marking and, where the overhang exceeds the permitted limit, an authorised permit; night marking must be reflective and visible from a distance.

Scan 12–15 seconds ahead of the vehicle and keep a space cushion on all sides; identify escape routes before a hazard develops rather than reacting after it appears.

Typical Saudi highway hazards include drifting sand, camels and livestock, unlit slow vehicles at night, sudden lane changes by cars and aggressive overtaking on single-carriageway roads.

A tyre blow-out at speed: hold the steering firmly with both hands, avoid hard braking, ease off the accelerator and let the vehicle slow before steering to the shoulder.

Brake failure: pump the pedal if air pressure is suspect, downshift progressively, use the engine brake and retarder, and use the emergency or spring brake; look for a runaway ramp or safe runoff.

Skid recovery: release the brake or throttle to restore wheel rotation, steer in the direction you want the front of the vehicle to go, and avoid overcorrecting with a long wheelbase.

If a trailer starts to jack-knife, release the brakes momentarily to let the trailer straighten, then reapply gently; hard braking at that moment worsens the fold.

At a railway crossing or junction with restricted view, stop, look and listen; a laden truck cannot accelerate or stop quickly enough to gamble on a gap.

In fog or blowing dust, switch on low-beam headlights and hazard lights as required, reduce speed sharply, and be prepared to stop within the visible distance.

Fatigue impairs reaction time, attention and judgement in a way comparable to alcohol; a tired driver may experience micro-sleeps of several seconds without noticing.

Long-distance heavy vehicle driving requires scheduled rest breaks; the standard guidance is to stop and rest at least every 2 hours or sooner if concentration lapses.

Warning signs of fatigue: heavy eyelids, yawning, drifting within the lane, missing signs or exits, and difficulty remembering the last few kilometres.

The only effective remedy for fatigue is sleep; opening a window, loud music, caffeine or cold air provide only brief relief and do not restore alertness.

Alcohol and psychoactive drugs are prohibited while driving; they slow reactions, impair judgement of speed and distance, and cause overconfidence and risk-taking.

Prescription and over-the-counter medicines can cause drowsiness; drivers must check the label and ask a pharmacist or doctor before driving a heavy vehicle.

Driver fitness includes vision standards, hearing, and control of conditions such as epilepsy, diabetes and heart disease; certain conditions require medical review before a licence is issued or renewed.

Illness, severe stress and some sleep disorders increase crash risk; a driver who feels unwell should not start a trip, and employers should be informed of fitness concerns.

At an incident: stop, switch off the engine, switch on hazard lights, and set out warning triangles behind the vehicle - further back on fast roads - before assisting anyone.

Call the emergency services and the traffic police (Muroor) as required; in Saudi Arabia the unified emergency number is 911, and traffic accidents must be reported to the police for insurance and liability purposes.

Do not move an injured person unless there is immediate danger such as fire or traffic; suspected spinal injury makes unnecessary movement dangerous.

Control severe bleeding with direct pressure and a clean dressing; keep the casualty warm and monitor breathing until help arrives.

If the vehicle is on fire or leaking fuel, move people well away and upwind; a heavy vehicle fire can involve fuel, cargo and pressurised systems, so do not attempt to fight a large fire.

Record the scene: other vehicles' plates, driver details, insurance information, witness contacts, road and weather conditions, and photographs before vehicles are moved if it is safe to do so.

Report the incident to the operator or fleet manager promptly, complete the accident report factually, and do not admit liability at the scene.

After any incident, the vehicle must be inspected for brake, steering, tyre and structural damage before it is returned to service.

Traffic signals override signs and road markings; a police officer directing traffic overrides all signals and markings, so obey the officer's hand signals first.

A flashing amber signal means proceed with caution and give way; a flashing red means stop and proceed only when clear, treating it like a stop sign.

Yellow box junctions and pedestrian crossings must be kept clear; entering a junction you cannot clear is an offence even on a green light.

Lane-use signs and overhead gantries on highways may close a lane to heavy vehicles; ignoring a lane closure sign is a traffic violation.

Speed limits are maximums for ideal conditions only; a lower limit applies near schools, roadworks and in poor visibility, and exceeding a posted limit is enforced by fixed and mobile cameras.

Overtaking is prohibited where the centre line is solid, on the approach to a pedestrian crossing, at junctions and where visibility is restricted by a crest or bend.

Vehicle classes are distinguished by permissible gross weight and by use: light vehicles, heavy trucks, buses for passenger transport, and heavy equipment such as excavators and loaders.

A licence is valid only for the category endorsed on it; driving a heavier class than the licence permits is treated as driving without the correct licence.

Trailer and semi-trailer combinations require the appropriate heavy combination entitlement and a coupling rated for the laden trailer weight.

Height, width and length limits apply to heavy vehicles and combinations; exceeding them requires an oversize permit and route approval.

Registration and insurance must match the vehicle's actual use; a goods vehicle used to carry passengers may void insurance cover in a collision.

Check tyre pressures cold against the manufacturer's specification; underinflation causes heat build-up and blow-outs, and dual tyres must not touch or be mismatched in diameter.

Test all lights with a helper or by reflection: headlights, brake lights, indicators, hazard lights, side markers, reverse lights and trailer lights.

Check the fifth wheel or coupling for wear and secure locking, and confirm the trailer landing legs are fully raised and the air lines are properly connected and not chafed.

Walk-around includes checking for loose mudguards, cracked mirrors, insecure battery, missing wheel nut indicators and any fresh oil, fuel or coolant drips under the vehicle.

A vehicle with an expired inspection certificate, defective brakes or unsafe tyres must be taken out of service, not driven to the workshop loaded.

Drain air tanks daily to remove moisture and oil; water in the system can freeze or corrode valves and cause brake drag or failure.

A brake chamber pushrod stroke beyond the adjustment limit means the brakes are out of adjustment and the vehicle is unroadworthy until corrected.

The low-pressure warning buzzer and light must activate before pressure falls below the safe operating level; if they do not, the vehicle must not be driven.

Test for air leaks by charging the system, switching off the engine and observing the gauge; a pressure drop beyond the manufacturer's limit indicates a leak requiring repair.

On a dual-circuit system, a failure in one circuit leaves partial braking; the driver must recognise the warning and stop safely rather than continue the trip.

The parking (spring) brake must hold the fully laden vehicle on a gradient; if it does not, the vehicle cannot be legally or safely operated.

Anti-lock braking systems prevent wheel lock-up but do not shorten stopping distance on all surfaces; the driver must still maintain a safe gap and speed.

Use the 3-second rule as a minimum in good conditions and extend to 4 seconds or more when laden, at night, in rain or dust, or when following a vehicle that blocks the view ahead.

Speed must allow stopping within the distance seen to be clear; on a crest, in fog or blowing dust, visible distance rather than the posted limit sets the safe speed.

Select a low gear before a long descent so engine braking controls speed; if the vehicle gains speed in that gear, change down before the speed builds.

Heavy vehicles should keep right and use the left lane only to overtake or to follow a mandatory direction; return to the right lane as soon as it is safe.

At roundabouts and junctions, slow early and check mirrors and blind spots; a laden truck needs far more time and distance to stop than a car.

Keep total weight within the permissible GVW and each axle within its rated limit; distribute load so the steering axle retains grip and no axle is overloaded.

Keep the centre of gravity low and centred between the axles; a high or rearward load reduces steering-axle grip and raises rollover risk.

Secure cargo with rated straps, chains or twist locks; the aggregate lashing strength must suit the load, and every anchor point must be sound.

Restrain the load against forward, rearward and lateral movement; a load that can shift under braking can push through the cab.

Recheck lashings after the first few kilometres and at each stop; straps stretch and loads settle, so a secure load at departure may loosen later.

Cover loose aggregate with a tarpaulin so material cannot spill onto the road or strike following traffic.

Mark overhanging loads with reflective warning material at night and obtain a permit where the overhang exceeds the permitted limit.

Scan 12–15 seconds ahead and keep a space cushion on all sides; identify escape routes before a hazard develops rather than reacting after it appears.

Expect drifting sand, camels and livestock, unlit slow vehicles at night, and sudden lane changes by cars on single-carriageway roads.

Tyre blow-out: hold the steering firmly, avoid hard braking, ease off the accelerator and let the vehicle slow before steering to the shoulder.

Brake failure: pump the pedal if air pressure is suspect, downshift progressively, use the engine brake and retarder, then apply the emergency or spring brake.

Skid recovery: release the brake or throttle to restore wheel rotation and steer in the direction you want the front of the vehicle to go.

If a trailer starts to jack-knife, release the brakes briefly to let it straighten, then reapply gently; hard braking worsens the fold.

In fog or blowing dust, use low-beam headlights and hazard lights as required, reduce speed sharply and be ready to stop within the visible distance.

Fatigue slows reaction time, attention and judgement; micro-sleeps of several seconds can occur without the driver noticing.

Long-distance driving requires scheduled rest breaks - at least every 2 hours or sooner if concentration lapses.

Warning signs include heavy eyelids, yawning, lane drifting, missing signs or exits, and difficulty remembering the last few kilometres.

The only effective remedy for fatigue is sleep; fresh air, loud music and caffeine give only brief relief and do not restore alertness.

Alcohol and psychoactive drugs are prohibited while driving; they slow reactions, impair speed and distance judgement, and cause overconfidence.

Prescription and over-the-counter medicines can cause drowsiness; check the label and ask a pharmacist or doctor before driving a heavy vehicle.

Fitness includes vision, hearing and control of conditions such as epilepsy, diabetes and heart disease; some conditions require medical review before licensing.

Illness, severe stress and sleep disorders raise crash risk; a driver who feels unwell should not start a trip and should inform the operator.

At an incident: stop, switch off the engine, switch on hazard lights and set out warning triangles behind the vehicle, further back on fast roads, before assisting anyone.

Call the emergency services and traffic police (Muroor) as required; in Saudi Arabia the unified emergency number is 911, and accidents must be reported to police for insurance and liability purposes.

Do not move an injured person unless there is immediate danger such as fire or traffic; suspected spinal injury makes unnecessary movement dangerous.

Control severe bleeding with direct pressure and a clean dressing; keep the casualty warm and monitor breathing until help arrives.

If the vehicle is on fire or leaking fuel, move people well away and upwind; a heavy vehicle fire can involve fuel, cargo and pressurised systems, so do not fight a large fire.

Record the scene: other vehicles' plates, driver details, insurance information, witness contacts, road and weather conditions, and photographs before vehicles are moved if it is safe.

Report the incident to the operator promptly, complete the accident report factually, and do not admit liability at the scene.

After any incident, inspect the vehicle for brake, steering, tyre and structural damage before returning it to service.