DTT HGV Road Signs

Question 1

What does a circular sign with a red border showing a truck silhouette mean?

Accepted Answer

No entry for goods vehicles (or vehicles over the weight shown)

Answer

A circular regulatory sign with a red border and a truck silhouette prohibits entry for goods vehicles. If a weight is shown (e.g., 7.5t), it applies to vehicles exceeding that weight. This is commonly seen in residential areas and on weight-restricted bridges.

Question 2

What does a triangular warning sign showing a steep incline with '10%' indicate?

Accepted Answer

A steep hill ahead with a gradient of 10% — select appropriate gear

Answer

This triangular warning sign indicates a steep hill with a 10% gradient (1 metre rise for every 10 metres of road). Truck and bus drivers should select an appropriate low gear before the descent and avoid over-reliance on brakes.

Question 3

What does a rectangular sign with 'LOW BRIDGE' and a height measurement indicate?

Accepted Answer

The maximum height of vehicle that can safely pass under the bridge ahead

Answer

Low bridge signs show the maximum safe clearance height. Drivers of tall vehicles must know their vehicle's height and must not attempt to pass under the bridge if their vehicle exceeds the stated clearance. Bridge strikes are a serious and costly offence.

Question 4

What does a blue circular sign showing a truck and a car side by side (with the truck crossed out) mean?

Accepted Answer

No overtaking by heavy goods vehicles

Answer

This mandatory sign prohibits overtaking by heavy goods vehicles. It is typically placed on sections of road where truck overtaking manoeuvres would be dangerous or cause excessive traffic delays, such as on long uphill sections.

Question 5

What does a sign showing an axle weight limit (e.g., '8t' with an axle symbol) mean?

Accepted Answer

No vehicle with any axle weight exceeding the stated limit may use this road

Answer

An axle weight limit sign restricts individual axle weights, not total vehicle weight. This is different from a gross weight limit. A vehicle might be within the total weight limit but still exceed the axle weight limit, especially if poorly loaded.

Irish DTT Truck/Bus Practice Test

Irish DTT Truck/Bus Practice Test

DTT HGV Road Signs