Vehicle dimensions, height and clearance awareness
This section covers vehicle height, width, length and clearance. The exam tests whether you can plan a route and avoid bridge strikes, overhead cables and narrow-road incidents.
Core rules
Know your vehicle’s actual height with the load, not just the cab height. Add the tallest point: roof equipment, exhaust stack, load or crane. Compare it with posted clearance signs; if the clearance is lower than your height, do not proceed. Width matters in narrow lanes, checkpoints and roadworks; mirrors and overhanging loads increase effective width. Length affects turning circles and rear swing. Plan routes for low bridges, tunnels, weight restrictions and weak roads. When unsure, stop and ask or use a spotter; reversing out of a low bridge is safer than striking it.
Worked example
Your truck is 4.15 m high with the load. A bridge sign shows 4.0 m. The difference is 15 cm, but road camber, suspension movement and load settling can reduce clearance further. The correct decision is to divert, not to “creep under slowly”.
Traps
Measuring only the cab; trusting a route that was clear for a car; ignoring overhanging trees and cables; and forgetting that mirrors and rear overhang need extra space.