What is the taxicab exception and when does it apply?

In general, when a public transit passenger randomly chooses from among a number of taxicab companies providing service, the testing regulations do not apply. The rationale for this is the practical difficulty of trying to administer a drug and alcohol testing program in connection with multiple companies. An example of this scenario is a guaranteed ride home program, in which the transit agency contracts with multiple (two or more) taxicab companies in the area and a passenger may choose which taxicab company to contact to get a ride home.