taxi fares can vary depending on the destination and time of day, as well as other factors that may influence the ride such as traffic and the season - preset estimations are available, but travelers must bare in mind that nothing is set in stone, the best way is to simply keep an eye on the taxi meter. taxis are legally obliged to follow two basic rates also known as bandeira um and bandeira dois (flag one and flag two) - these fares use distance and time as elements to conclude the value of the journey. convential cabs and special taxis, such as radio and airport taxis, all have different rates - special taxis need to be booked by phone or they can be accessed at their designated stop, or base, such as the airport terminal.