A transportation management system coordinates the transportation of riders by drivers integrated with the system. To provide control to the rider of the route used during a trip provided by a given driver, the transportation management system computes several alternative routing options between the trip's origin location and destination location. These alternative routing options may be computed according to the rider's preferences and/or based on different optimization functions that optimize various trip parameters, for example, cost, time, traffic, and distance. The rider selects one of the alternative routing options as the preferred route between the origin location and the destination location. The transportation management system automatically communicates the routing option selected by the rider to the driver without requiring the rider to personally tell the driver of her preference.