What is the effect of driving a heavily loaded rigid truck on a road that has a posted 'No Trucks' restriction but the driver believes the road is the quickest route?

1. It is permissible if the driver has prior approval from their employer
2. It is an offence; the driver must use an alternative route regardless of convenience
3. It is allowed if the driver uses hazard lights to warn other road users
4. The restriction applies only to vehicles exceeding 20 tonnes