DTT HGV Motorway Driving and CPC Requirements 1 — Questions and Answers
Question 1: What is the maximum speed limit for trucks over 3.5 tonnes on an Irish motorway?
- 90 km/h — enforced by the mandatory speed limiter (Correct answer)
- 120 km/h — same as cars
- 100 km/h for articulated trucks only
- 80 km/h for all commercial vehicles
Correct answer: 90 km/h — enforced by the mandatory speed limiter
Trucks over 3.5 tonnes are limited to 90 km/h on Irish motorways by mandatory speed limiters. This limit applies regardless of the posted motorway limit of 120 km/h for cars.
Question 2: What lanes are trucks permitted to use on a three-lane motorway in Ireland?
- Lane 1 (nearside/left) and lane 2 (middle) — lane 3 (offside/right) is restricted to cars and certain vehicles only (Correct answer)
- All three lanes — trucks may use any lane
- Lane 1 only — trucks must never use lane 2
- Lane 2 for overtaking only — lane 1 mandatory otherwise
Correct answer: Lane 1 (nearside/left) and lane 2 (middle) — lane 3 (offside/right) is restricted to cars and certain vehicles only
On a three-lane motorway, trucks over 7.5 tonnes are generally restricted from using the outer (right-hand) lane unless it is necessary to do so in exceptional circumstances. They should use lanes 1 and 2 only.
Question 3: What must a truck or bus driver do before joining a motorway from a slip road?
- Accelerate to match motorway traffic speed on the slip road, check mirrors and blind spots, and merge safely into a gap in the left lane (Correct answer)
- Stop at the end of the slip road and wait for a safe gap
- Flash headlights to signal intent to merge
- Use the hard shoulder to gain speed after the slip road ends
Correct answer: Accelerate to match motorway traffic speed on the slip road, check mirrors and blind spots, and merge safely into a gap in the left lane
Use the full length of the slip road to reach motorway speed, carry out MSM routine (mirrors, signal, manoeuvre), check the blind spot, and merge smoothly into a gap. Merging slowly disrupts motorway traffic and is dangerous.
Question 4: What is the procedure when a truck's load shifts during motorway driving?
- Move to the hard shoulder safely, stop, switch on hazard lights, and secure the load before continuing — do not continue with an unstable load (Correct answer)
- Continue to the next motorway services and then secure the load
- Reduce speed and continue — a shifted load is manageable at lower speeds
- Call the depot from the cab — they will send assistance to escort the vehicle
Correct answer: Move to the hard shoulder safely, stop, switch on hazard lights, and secure the load before continuing — do not continue with an unstable load
A shifted load changes the vehicle's handling, weight distribution, and may be in imminent danger of falling. Stop on the hard shoulder immediately, use hazard lights and warning triangles, and secure the load before proceeding.
Question 5: What is the correct response when a tyre blows out on a truck travelling on a motorway?
- Grip the steering firmly, ease off the throttle gradually, do not brake sharply, steer to the hard shoulder, and stop safely (Correct answer)
- Brake hard to stop as quickly as possible
- Continue to the next junction — a single tyre blowout on a multi-axle truck is manageable at speed
- Sound the horn and switch on hazard lights before braking
Correct answer: Grip the steering firmly, ease off the throttle gradually, do not brake sharply, steer to the hard shoulder, and stop safely
A tyre blowout on a heavy vehicle at speed causes a sudden pull toward the affected side. Resist braking immediately — firm wheel grip and gradual deceleration gives the best chance of maintaining control while pulling over.
Question 6: What action must a truck driver take when encountering a 'Smart Motorway' mandatory variable speed limit?
- Comply with the displayed mandatory speed limit — gantry-displayed limits override default limits (Correct answer)
- Mandatory speed limits on gantries do not apply to commercial vehicles below 90 km/h
- Reduce to the displayed speed only if congestion is visible
- Smart motorway limits are advisory for trucks — follow the speed limiter setting
Correct answer: Comply with the displayed mandatory speed limit — gantry-displayed limits override default limits
Variable mandatory speed limits displayed on motorway gantries are legally binding and override the default motorway limit. All vehicles, including trucks, must comply — even if the displayed limit is below their speed limiter setting.
DTT HGV Motorway Driving and CPC Requirements 1
What is the maximum speed limit for trucks over 3.5 tonnes on an Irish motorway?