Answer from Tom Baker:
Many haulage companies train and equip their drivers to deal with situations like these.
The leak from the barrel can be temporarily stopped by rolling the drum over so the puncture is at the top. The leaking barrel can then be sealed in a salvage ‘over drum’, which safely encloses the entire barrel. However, a spill of acid onto the carriageway is a serious event and the emergency services need to be notified immediately, to make sure the public is safe. Failure to do this can be expensive! The HSE has previously imposed fines of £20,000 on companies that have failed to act responsibly.
Tom Baker is a senior responder at the National Chemical Emergency Centre