How can governments ensure that private transport companies do not neglect safety regulations?

(Intro: Explain the problem)
In recent years, certain countries have adopted a policy of allowing private businesses to run transport systems which were previously publicly owned. However, many people are concerned about how transport safety standards would be upheld once a government gave up control. There are several potential solutions which I believe would be effective.

(Body 1: Govt. Laws)
One of the major roles of government is to make and enforce laws. If they made it against the law to endanger public safety, any company that did not comply with the regulations could be dealt with in a court. The advantage of this policy would be that the inevitable bad publicity from such a trial would certainly be a strong motivation for companies to maintain good standards.

(Body 2: Inspections & Fines)
Although the government would not be running the transport system, there is no reason that they could not control it by means of inspections and penalties if companies were not operating safely. If the government found dangerous practices resulting from an inspection, they could refuse to allow that company to continue trading. They might also consider financial penalties for lesser problems. The drawback of these ideas is that they would involve the government in running an inspection system which may well be expensive.

(Body 3: Don't allow private ownership)
A final solution would be to consider changing the law to stop private companies running any public transport. However, such a proposal might be highly unpopular with voters if they felt private companies had made improvements.

To summarize, the problem of balancing private profit with public safety on buses and trains is not easy to resolve. However, it is my vies that if governments carried out regular inspections supported by a system of tough penalties, then public safety would be maintained.