The Transport Research...

The Transport Research Laboratory (TRL) surveyed 80,000 vehicles on the M3, M4 and M5, plus the A14 and A4, using special laser equipment (right). The Berkshire-based group found many HGVs were 4.9 metres tall, meaning they"re dangerously close to the standard height for motorway and road bridges, which is 5.03 metres.

A TRL spokesman said: "Although no manufacturer is likely to make a lorry more than 5.03 metres tall, some are getting close. This doesn"t leave much room for manoeuvre, especially as factors such as road resurfacing, tyres and braking - even the effect of wind - can reduce the actual gap available." The height of lorries used to be restricted to 4.5 metres, but the limit was scrapped in 1995.